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• IIS 7.5 Manager crashes when adding a custom error page

  - by dig412

  I'm running a local IIS 7.5 server in Win 7 Pro, and I'm trying to add a custom error page for 403 responses. When I click OK to add a custom error page for my site, IIS Manager just vanishes. The server is still running, and I can re-start IIS Manager, but the new page has not been saved. I've also tried adding it directly to web.config, but that just gives me The page cannot be displayed because an internal server error has occurred. Does anyone know why this might be happening? Edit: The event log implies that an invalid character in the path caused the crash, but It occured even when I copied & pasted a path from a valid entry. Application error log: IISMANAGER_CRASH IIS Manager terminated unexpectedly. Exception:System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. --- System.ArgumentException: Illegal characters in path. at System.IO.Path.CheckInvalidPathChars(String path) at System.IO.Path.IsPathRooted(String path) at Microsoft.Web.Management.Iis.CustomErrors.CustomErrorsForm.OnAccept() at Microsoft.Web.Management.Client.Win32.TaskForm.OnOKButtonClick(Object sender, EventArgs e) at System.Windows.Forms.Control.OnClick(EventArgs e) at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ButtonBase.WndProc(Message& m) at System.Windows.Forms.Button.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Form.ShowDialog(IWin32Window owner) at Microsoft.Web.Management.Host.UserInterface.ManagementUIService.ShowDialogInternal(Form form, IWin32Window parent) at Microsoft.Web.Management.Host.UserInterface.ManagementUIService.Microsoft.Web.Management.Client.Win32.IManagementUIService.ShowDialog(DialogForm form) at Microsoft.Web.Management.Client.Win32.ModulePage.ShowDialog(DialogForm form) at Microsoft.Web.Management.Iis.CustomErrors.CustomErrorsPage.AddCustomError() --- End of inner exception stack trace --- at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) at Microsoft.Web.Management.Client.TaskList.InvokeMethod(String methodName, Object userData) at Microsoft.Web.Management.Host.UserInterface.Tasks.MethodTaskItemLine.InvokeMethod() at System.Windows.Forms.LinkLabel.OnMouseUp(MouseEventArgs e) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.Label.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at Microsoft.Web.Management.Host.Shell.ShellApplication.Execute(Boolean localDevelopmentMode, Boolean resetPreferences, Boolean resetPreferencesNoLaunch) Process:InetMgr

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• postfix: Temporary lookup failure for FQDN

  - by Thufir

  I'm using the FQDN of dur.bounceme.net which I want to resolve(?) to localhost. That is, I want mail to [email protected] to get delivered to user@localhost. I've tried following the Ubuntu guide on this and seem to be going in circles a bit. root@dur:~# root@dur:~# postfix stop postfix/postfix-script: stopping the Postfix mail system root@dur:~# postfix start postfix/postfix-script: starting the Postfix mail system root@dur:~# telnet dur.bounceme.net 25 Trying 127.0.1.1... telnet: Unable to connect to remote host: Connection refused root@dur:~# root@dur:~# telnet localhost 25 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. 220 dur.bounceme.net ESMTP Postfix (Ubuntu) ehlo dur 250-dur.bounceme.net 250-PIPELINING 250-SIZE 10240000 250-VRFY 250-ETRN 250-STARTTLS 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN mail from:[email protected] 250 2.1.0 Ok rcpt to:[email protected] 451 4.3.0 <[email protected]>: Temporary lookup failure rcpt to:thufir@localhost 451 4.3.0 <thufir@localhost>: Temporary lookup failure quit 221 2.0.0 Bye Connection closed by foreign host. root@dur:~# root@dur:~# grep telnet /var/log/mail.log Aug 28 00:24:45 dur postfix/smtpd[18256]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 451 4.3.0 <thufir@localhost>: Temporary lookup failure; from=<[email protected]> to=<thufir@localhost> proto=ESMTP helo=<dur> Aug 28 00:24:58 dur postfix/smtpd[18256]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 451 4.3.0 <[email protected]>: Temporary lookup failure; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<dur> Aug 28 00:54:55 dur postfix/smtpd[18825]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 451 4.3.0 <[email protected]>: Temporary lookup failure; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<dur> Aug 28 00:55:08 dur postfix/smtpd[18825]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 451 4.3.0 <thufir@localhost>: Temporary lookup failure; from=<[email protected]> to=<thufir@localhost> proto=ESMTP helo=<dur> root@dur:~# root@dur:~# postconf -n alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases append_dot_mydomain = no biff = no broken_sasl_auth_clients = yes config_directory = /etc/postfix default_transport = smtp home_mailbox = Maildir/ inet_interfaces = loopback-only mailbox_command = /usr/lib/dovecot/deliver -c /etc/dovecot/conf.d/01-mail-stack-delivery.conf -m "${EXTENSION}" mailbox_size_limit = 0 mailman_destination_recipient_limit = 1 mydestination = dur, dur.bounceme.net, localhost.bounceme.net, localhost myhostname = dur.bounceme.net mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 readme_directory = no recipient_delimiter = + relay_domains = lists.dur.bounceme.net relay_transport = relay relayhost = smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache smtp_use_tls = yes smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) smtpd_recipient_restrictions = reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination smtpd_sasl_auth_enable = yes smtpd_sasl_authenticated_header = yes smtpd_sasl_local_domain = $myhostname smtpd_sasl_path = private/dovecot-auth smtpd_sasl_security_options = noanonymous smtpd_sasl_type = dovecot smtpd_tls_auth_only = yes smtpd_tls_cert_file = /etc/ssl/certs/ssl-mail.pem smtpd_tls_key_file = /etc/ssl/private/ssl-mail.key smtpd_tls_mandatory_ciphers = medium smtpd_tls_mandatory_protocols = SSLv3, TLSv1 smtpd_tls_received_header = yes smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtpd_use_tls = yes tls_random_source = dev:/dev/urandom transport_maps = hash:/etc/postfix/transport root@dur:~#

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• Openvpn issue with linux

  - by catsy

  So I've tried to setup openvpn, I followed some guide but it's stuck att "initialization sequence completed" with no connection and I can't find any working solution... here's the log: $Sun Sep 23 19:14:32 2012 OpenVPN 2.1.0 i486-pc-linux-gnu [SSL] [LZO2] [EPOLL] [PKCS11] [MH] [PF_INET6] [eurephia] built on Jul 20 2010 Enter Auth Username:pumpedup Enter Auth Password: Sun Sep 23 19:14:37 2012 WARNING: No server certificate verification method has been enabled. See http://openvpn.net/howto.html#mitm for more info. Sun Sep 23 19:14:37 2012 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables Sun Sep 23 19:14:37 2012 LZO compression initialized Sun Sep 23 19:14:37 2012 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ] Sun Sep 23 19:14:38 2012 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ] Sun Sep 23 19:14:38 2012 Local Options hash (VER=V4): '41690919' Sun Sep 23 19:14:38 2012 Expected Remote Options hash (VER=V4): '530fdded' Sun Sep 23 19:14:38 2012 Socket Buffers: R=[163840-131072] S=[163840-131072] Sun Sep 23 19:14:38 2012 UDPv4 link local: [undef] Sun Sep 23 19:14:38 2012 UDPv4 link remote: [AF_INET]192.162.102.162:1194 Sun Sep 23 19:14:38 2012 TLS: Initial packet from [AF_INET]192.162.102.162:1194, sid=87a95723 a6d7b7f9 Sun Sep 23 19:14:38 2012 WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this Sun Sep 23 19:14:38 2012 VERIFY OK: depth=1, /C=NV/ST=NV/L=nVPN/O=nVpn/CN=nVpn_CA/[email protected] Sun Sep 23 19:14:38 2012 VERIFY OK: depth=0, /C=NV/ST=NV/L=nVPN/O=nVpn/CN=server/[email protected] Sun Sep 23 19:14:39 2012 WARNING: 'link-mtu' is used inconsistently, local='link-mtu 1542', remote='link-mtu 6042' Sun Sep 23 19:14:39 2012 WARNING: 'tun-mtu' is used inconsistently, local='tun-mtu 1500', remote='tun-mtu 6000' Sun Sep 23 19:14:39 2012 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key Sun Sep 23 19:14:39 2012 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Sun Sep 23 19:14:39 2012 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key Sun Sep 23 19:14:39 2012 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Sun Sep 23 19:14:39 2012 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA Sun Sep 23 19:14:39 2012 [server] Peer Connection Initiated with [AF_INET]192.162.102.162:1194 Sun Sep 23 19:14:41 2012 SENT CONTROL [server]: 'PUSH_REQUEST' (status=1) Sun Sep 23 19:14:41 2012 PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1,dhcp-option DNS 8.8.8.8,dhcp-option DNS 8.8.8.8,route 10.102.162.1,topology net30,ping 10,ping-restart 120,ifconfig 10.102.162.6 10.102.162.5' Sun Sep 23 19:14:41 2012 OPTIONS IMPORT: timers and/or timeouts modified Sun Sep 23 19:14:41 2012 OPTIONS IMPORT: --ifconfig/up options modified Sun Sep 23 19:14:41 2012 OPTIONS IMPORT: route options modified Sun Sep 23 19:14:41 2012 OPTIONS IMPORT: --ip-win32 and/or --dhcp-option options modified Sun Sep 23 19:14:41 2012 ROUTE default_gateway=10.0.2.2 Sun Sep 23 19:14:41 2012 TUN/TAP device tun0 opened Sun Sep 23 19:14:41 2012 TUN/TAP TX queue length set to 100 Sun Sep 23 19:14:41 2012 /sbin/ifconfig tun0 10.102.162.6 pointopoint 10.102.162.5 mtu 1500 Sun Sep 23 19:14:41 2012 /sbin/route add -net 192.162.102.162 netmask 255.255.255.255 gw 10.0.2.2 Sun Sep 23 19:14:41 2012 /sbin/route add -net 0.0.0.0 netmask 128.0.0.0 gw 10.102.162.5 Sun Sep 23 19:14:41 2012 /sbin/route add -net 128.0.0.0 netmask 128.0.0.0 gw 10.102.162.5 Sun Sep 23 19:14:41 2012 /sbin/route add -net 10.102.162.1 netmask 255.255.255.255 gw 10.102.162.5 Sun Sep 23 19:14:41 2012 Initialization Sequence Completed

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• Oracle Virtual Server OEL vm fails to start - kernel panic on cpu identify

  - by Towndrunk

  I am in the process of following a guide to setup various oracle vm templates, so far I have installed OVS 2. 2 and got the OVM Manager working, imported the template for OEL5U5 and created a vm from it.. the problem comes when starting that vm. The log in the OVMM console shows the following; Update VM Status - Running Configure CPU Cap Set CPU Cap: failed:<Exception: failed:<Exception: ['xm', 'sched-credit', '-d', '32_EM11g_OVM', '-c', '0'] => Error: Domain '32_EM11g_OVM' does not exist. StackTrace: File "/opt/ovs-agent-2.3/OVSXXenVMConfig.py", line 2531, in xen_set_cpu_cap run_cmd(args=['xm', File "/opt/ovs-agent-2.3/OVSCommons.py", line 92, in run_cmd raise Exception('%s => %s' % (args, err)) The xend.log shows; [2012-11-12 16:42:01 7581] DEBUG (DevController:139) Waiting for devices vtpm [2012-11-12 16:42:01 7581] INFO (XendDomain:1180) Domain 32_EM11g_OVM (3) unpaused. [2012-11-12 16:42:03 7581] WARNING (XendDomainInfo:1907) Domain has crashed: name=32_EM11g_OVM id=3. [2012-11-12 16:42:03 7581] ERROR (XendDomainInfo:2041) VM 32_EM11g_OVM restarting too fast (Elapsed time: 11.377262 seconds). Refusing to restart to avoid loops .> [2012-11-12 16:42:03 7581] DEBUG (XendDomainInfo:2757) XendDomainInfo.destroy: domid=3 [2012-11-12 16:42:12 7581] DEBUG (XendDomainInfo:2230) Destroying device model [2012-11-12 16:42:12 7581] INFO (image:553) 32_EM11g_OVM device model terminated I have set_on_crash="preserve" in the vm.cfg and have then run xm create -c to get the console screen while booting and this is the log of what happens.. Started domain 32_EM11g_OVM (id=4) Bootdata ok (command line is ro root=LABEL=/ ) Linux version 2.6.18-194.0.0.0.3.el5xen ([email protected]) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)) #1 SMP Mon Mar 29 18:27:00 EDT 2010 BIOS-provided physical RAM map: Xen: 0000000000000000 - 0000000180800000 (usable)> No mptable found. Built 1 zonelists. Total pages: 1574912 Kernel command line: ro root=LABEL=/ Initializing CPU#0 PID hash table entries: 4096 (order: 12, 32768 bytes) Xen reported: 1600.008 MHz processor. Console: colour dummy device 80x25 Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes) Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes) Software IO TLB disabled Memory: 6155256k/6299648k available (2514k kernel code, 135548k reserved, 1394k data, 184k init) Calibrating delay using timer specific routine.. 4006.42 BogoMIPS (lpj=8012858) Security Framework v1.0.0 initialized SELinux: Initializing. selinux_register_security: Registering secondary module capability Capability LSM initialized as secondary Mount-cache hash table entries: 256 CPU: L1 I Cache: 64K (64 bytes/line), D cache 16K (64 bytes/line) CPU: L2 Cache: 2048K (64 bytes/line) general protection fault: 0000 [1] SMP last sysfs file: CPU 0 Modules linked in: Pid: 0, comm: swapper Not tainted 2.6.18-194.0.0.0.3.el5xen #1 RIP: e030:[ffffffff80271280] [ffffffff80271280] identify_cpu+0x210/0x494 RSP: e02b:ffffffff80643f70 EFLAGS: 00010212 RAX: 0040401000810008 RBX: 0000000000000000 RCX: 00000000c001001f RDX: 0000000000404010 RSI: 0000000000000001 RDI: 0000000000000005 RBP: ffffffff8063e980 R08: 0000000000000025 R09: ffff8800019d1000 R10: 0000000000000026 R11: ffff88000102c400 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffffffff805d2000(0000) knlGS:0000000000000000 CS: e033 DS: 0000 ES: 0000 Process swapper (pid: 0, threadinfo ffffffff80642000, task ffffffff804f4b80) Stack: 0000000000000000 ffffffff802d09bb ffffffff804f4b80 0000000000000000 0000000021100800 0000000000000000 0000000000000000 ffffffff8064cb00 0000000000000000 0000000000000000 Call Trace: [ffffffff802d09bb] kmem_cache_zalloc+0x62/0x80 [ffffffff8064cb00] start_kernel+0x210/0x224 [ffffffff8064c1e5] _sinittext+0x1e5/0x1eb Code: 0f 30 b8 73 00 00 00 f0 0f ab 45 08 e9 f0 00 00 00 48 89 ef RIP [ffffffff80271280] identify_cpu+0x210/0x494 RSP ffffffff80643f70 0 Kernel panic - not syncing: Fatal exception clear as mud to me. are there any other logs that will help me? I have now deployed another vm from the same template and used the default vm settings rather than adding more memory etc - I get exactly the same error.

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• More CPU cores may not always lead to better performance – MAXDOP and query memory distribution in spotlight

  - by sqlworkshops

  More hardware normally delivers better performance, but there are exceptions where it can hinder performance. Understanding these exceptions and working around it is a major part of SQL Server performance tuning.   When a memory allocating query executes in parallel, SQL Server distributes memory to each task that is executing part of the query in parallel. In our example the sort operator that executes in parallel divides the memory across all tasks assuming even distribution of rows. Common memory allocating queries are that perform Sort and do Hash Match operations like Hash Join or Hash Aggregation or Hash Union.   In reality, how often are column values evenly distributed, think about an example; are employees working for your company distributed evenly across all the Zip codes or mainly concentrated in the headquarters? What happens when you sort result set based on Zip codes? Do all products in the catalog sell equally or are few products hot selling items?   One of my customers tested the below example on a 24 core server with various MAXDOP settings and here are the results:MAXDOP 1: CPU time = 1185 ms, elapsed time = 1188 msMAXDOP 4: CPU time = 1981 ms, elapsed time = 1568 msMAXDOP 8: CPU time = 1918 ms, elapsed time = 1619 msMAXDOP 12: CPU time = 2367 ms, elapsed time = 2258 msMAXDOP 16: CPU time = 2540 ms, elapsed time = 2579 msMAXDOP 20: CPU time = 2470 ms, elapsed time = 2534 msMAXDOP 0: CPU time = 2809 ms, elapsed time = 2721 ms - all 24 cores.In the above test, when the data was evenly distributed, the elapsed time of parallel query was always lower than serial query.   Why does the query get slower and slower with more CPU cores / higher MAXDOP? Maybe you can answer this question after reading the article; let me know: [email protected].   Well you get the point, let’s see an example.   The best way to learn is to practice. To create the below tables and reproduce the behavior, join the mailing list by using this link: www.sqlworkshops.com/ml and I will send you the table creation script.   Let’s update the Employees table with 49 out of 50 employees located in Zip code 2001. update Employees set Zip = EmployeeID / 400 + 1 where EmployeeID % 50 = 1 update Employees set Zip = 2001 where EmployeeID % 50 != 1 go update statistics Employees with fullscan go   Let’s create the temporary table #FireDrill with all possible Zip codes. drop table #FireDrill go create table #FireDrill (Zip int primary key) insert into #FireDrill select distinct Zip from Employees update statistics #FireDrill with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --First serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) goThe query took 1011 ms to complete.   The execution plan shows the 77816 KB of memory was granted while the estimated rows were 799624.  No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 1912 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 799624.  The estimated number of rows between serial and parallel plan are the same. The parallel plan has slightly more memory granted due to additional overhead. Sort properties shows the rows are unevenly distributed over the 4 threads.   Sort Warnings in SQL Server Profiler.   Intermediate Summary: The reason for the higher duration with parallel plan was sort spill. This is due to uneven distribution of employees over Zip codes, especially concentration of 49 out of 50 employees in Zip code 2001. Now let’s update the Employees table and distribute employees evenly across all Zip codes.   update Employees set Zip = EmployeeID / 400 + 1 go update statistics Employees with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go   The query took 751 ms to complete.  The execution plan shows the 77816 KB of memory was granted while the estimated rows were 784707.  No Sort Warnings in SQL Server Profiler.   Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 661 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 784707.  Sort properties shows the rows are evenly distributed over the 4 threads. No Sort Warnings in SQL Server Profiler.    Intermediate Summary: When employees were distributed unevenly, concentrated on 1 Zip code, parallel sort spilled while serial sort performed well without spilling to tempdb. When the employees were distributed evenly across all Zip codes, parallel sort and serial sort did not spill to tempdb. This shows uneven data distribution may affect the performance of some parallel queries negatively. For detailed discussion of memory allocation, refer to webcasts available at www.sqlworkshops.com/webcasts.     Some of you might conclude from the above execution times that parallel query is not faster even when there is no spill. Below you can see when we are joining limited amount of Zip codes, parallel query will be fasted since it can use Bitmap Filtering.   Let’s update the Employees table with 49 out of 50 employees located in Zip code 2001. update Employees set Zip = EmployeeID / 400 + 1 where EmployeeID % 50 = 1 update Employees set Zip = 2001 where EmployeeID % 50 != 1 go update statistics Employees with fullscan go  Let’s create the temporary table #FireDrill with limited Zip codes. drop table #FireDrill go create table #FireDrill (Zip int primary key) insert into #FireDrill select distinct Zip       from Employees where Zip between 1800 and 2001 update statistics #FireDrill with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go The query took 989 ms to complete.  The execution plan shows the 77816 KB of memory was granted while the estimated rows were 785594. No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 1799 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 785594.  Sort Warnings in SQL Server Profiler.    The estimated number of rows between serial and parallel plan are the same. The parallel plan has slightly more memory granted due to additional overhead.  Intermediate Summary: The reason for the higher duration with parallel plan even with limited amount of Zip codes was sort spill. This is due to uneven distribution of employees over Zip codes, especially concentration of 49 out of 50 employees in Zip code 2001.   Now let’s update the Employees table and distribute employees evenly across all Zip codes. update Employees set Zip = EmployeeID / 400 + 1 go update statistics Employees with fullscan go Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go The query took 250  ms to complete.  The execution plan shows the 9016 KB of memory was granted while the estimated rows were 79973.8.  No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0.  --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 85 ms to complete.  The execution plan shows the 13152 KB of memory was granted while the estimated rows were 784707.  No Sort Warnings in SQL Server Profiler.    Here you see, parallel query is much faster than serial query since SQL Server is using Bitmap Filtering to eliminate rows before the hash join.   Parallel queries are very good for performance, but in some cases it can hinder performance. If one identifies the reason for these hindrances, then it is possible to get the best out of parallelism. I covered many aspects of monitoring and tuning parallel queries in webcasts (www.sqlworkshops.com/webcasts) and articles (www.sqlworkshops.com/articles). I suggest you to watch the webcasts and read the articles to better understand how to identify and tune parallel query performance issues.   Summary: One has to avoid sort spill over tempdb and the chances of spills are higher when a query executes in parallel with uneven data distribution. Parallel query brings its own advantage, reduced elapsed time and reduced work with Bitmap Filtering. So it is important to understand how to avoid spills over tempdb and when to execute a query in parallel.   I explain these concepts with detailed examples in my webcasts (www.sqlworkshops.com/webcasts), I recommend you to watch them. The best way to learn is to practice. To create the above tables and reproduce the behavior, join the mailing list at www.sqlworkshops.com/ml and I will send you the relevant SQL Scripts.   Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   Disclaimer and copyright information:This article refers to organizations and products that may be the trademarks or registered trademarks of their various owners. Copyright of this article belongs to R Meyyappan / www.sqlworkshops.com. You may freely use the ideas and concepts discussed in this article with acknowledgement (www.sqlworkshops.com), but you may not claim any of it as your own work. This article is for informational purposes only; you use any of the suggestions given here entirely at your own risk.   Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   R Meyyappan [email protected] LinkedIn: http://at.linkedin.com/in/rmeyyappan  

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• C#/.NET Little Wonders: The Joy of Anonymous Types

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the .NET 3 Framework, Microsoft introduced the concept of anonymous types, which provide a way to create a quick, compiler-generated types at the point of instantiation.  These may seem trivial, but are very handy for concisely creating lightweight, strongly-typed objects containing only read-only properties that can be used within a given scope. Creating an Anonymous Type In short, an anonymous type is a reference type that derives directly from object and is defined by its set of properties base on their names, number, types, and order given at initialization.  In addition to just holding these properties, it is also given appropriate overridden implementations for Equals() and GetHashCode() that take into account all of the properties to correctly perform property comparisons and hashing.  Also overridden is an implementation of ToString() which makes it easy to display the contents of an anonymous type instance in a fairly concise manner. To construct an anonymous type instance, you use basically the same initialization syntax as with a regular type.  So, for example, if we wanted to create an anonymous type to represent a particular point, we could do this: 1: var point = new { X = 13, Y = 7 }; Note the similarity between anonymous type initialization and regular initialization.  The main difference is that the compiler generates the type name and the properties (as readonly) based on the names and order provided, and inferring their types from the expressions they are assigned to. It is key to remember that all of those factors (number, names, types, order of properties) determine the anonymous type.  This is important, because while these two instances share the same anonymous type: 1: // same names, types, and order 2: var point1 = new { X = 13, Y = 7 }; 3: var point2 = new { X = 5, Y = 0 }; These similar ones do not: 1: var point3 = new { Y = 3, X = 5 }; // different order 2: var point4 = new { X = 3, Y = 5.0 }; // different type for Y 3: var point5 = new {MyX = 3, MyY = 5 }; // different names 4: var point6 = new { X = 1, Y = 2, Z = 3 }; // different count Limitations on Property Initialization Expressions The expression for a property in an anonymous type initialization cannot be null (though it can evaluate to null) or an anonymous function.  For example, the following are illegal: 1: // Null can't be used directly. Null reference of what type? 2: var cantUseNull = new { Value = null }; 3:  4: // Anonymous methods cannot be used. 5: var cantUseAnonymousFxn = new { Value = () => Console.WriteLine(“Can’t.”) }; Note that the restriction on null is just that you can’t use it directly as the expression, because otherwise how would it be able to determine the type?  You can, however, use it indirectly assigning a null expression such as a typed variable with the value null, or by casting null to a specific type: 1: string str = null; 2: var fineIndirectly = new { Value = str }; 3: var fineCast = new { Value = (string)null }; All of the examples above name the properties explicitly, but you can also implicitly name properties if they are being set from a property, field, or variable.  In these cases, when a field, property, or variable is used alone, and you don’t specify a property name assigned to it, the new property will have the same name.  For example: 1: int variable = 42; 2:  3: // creates two properties named varriable and Now 4: var implicitProperties = new { variable, DateTime.Now }; Is the same type as: 1: var explicitProperties = new { variable = variable, Now = DateTime.Now }; But this only works if you are using an existing field, variable, or property directly as the expression.  If you use a more complex expression then the name cannot be inferred: 1: // can't infer the name variable from variable * 2, must name explicitly 2: var wontWork = new { variable * 2, DateTime.Now }; In the example above, since we typed variable * 2, it is no longer just a variable and thus we would have to assign the property a name explicitly. ToString() on Anonymous Types One of the more trivial overrides that an anonymous type provides you is a ToString() method that prints the value of the anonymous type instance in much the same format as it was initialized (except actual values instead of expressions as appropriate of course). For example, if you had: 1: var point = new { X = 13, Y = 42 }; And then print it out: 1: Console.WriteLine(point.ToString()); You will get: 1: { X = 13, Y = 42 } While this isn’t necessarily the most stunning feature of anonymous types, it can be handy for debugging or logging values in a fairly easy to read format. Comparing Anonymous Type Instances Because anonymous types automatically create appropriate overrides of Equals() and GetHashCode() based on the underlying properties, we can reliably compare two instances or get hash codes.  For example, if we had the following 3 points: 1: var point1 = new { X = 1, Y = 2 }; 2: var point2 = new { X = 1, Y = 2 }; 3: var point3 = new { Y = 2, X = 1 }; If we compare point1 and point2 we’ll see that Equals() returns true because they overridden version of Equals() sees that the types are the same (same number, names, types, and order of properties) and that the values are the same.   In addition, because all equal objects should have the same hash code, we’ll see that the hash codes evaluate to the same as well: 1: // true, same type, same values 2: Console.WriteLine(point1.Equals(point2)); 3:  4: // true, equal anonymous type instances always have same hash code 5: Console.WriteLine(point1.GetHashCode() == point2.GetHashCode()); However, if we compare point2 and point3 we get false.  Even though the names, types, and values of the properties are the same, the order is not, thus they are two different types and cannot be compared (and thus return false).  And, since they are not equal objects (even though they have the same value) there is a good chance their hash codes are different as well (though not guaranteed): 1: // false, different types 2: Console.WriteLine(point2.Equals(point3)); 3:  4: // quite possibly false (was false on my machine) 5: Console.WriteLine(point2.GetHashCode() == point3.GetHashCode()); Using Anonymous Types Now that we’ve created instances of anonymous types, let’s actually use them.  The property names (whether implicit or explicit) are used to access the individual properties of the anonymous type.  The main thing, once again, to keep in mind is that the properties are readonly, so you cannot assign the properties a new value (note: this does not mean that instances referred to by a property are immutable – for more information check out C#/.NET Fundamentals: Returning Data Immutably in a Mutable World). Thus, if we have the following anonymous type instance: 1: var point = new { X = 13, Y = 42 }; We can get the properties as you’d expect: 1: Console.WriteLine(“The point is: ({0},{1})”, point.X, point.Y); But we cannot alter the property values: 1: // compiler error, properties are readonly 2: point.X = 99; Further, since the anonymous type name is only known by the compiler, there is no easy way to pass anonymous type instances outside of a given scope.  The only real choices are to pass them as object or dynamic.  But really that is not the intention of using anonymous types.  If you find yourself needing to pass an anonymous type outside of a given scope, you should really consider making a POCO (Plain Old CLR Type – i.e. a class that contains just properties to hold data with little/no business logic) instead. Given that, why use them at all?  Couldn’t you always just create a POCO to represent every anonymous type you needed?  Sure you could, but then you might litter your solution with many small POCO classes that have very localized uses. It turns out this is the key to when to use anonymous types to your advantage: when you just need a lightweight type in a local context to store intermediate results, consider an anonymous type – but when that result is more long-lived and used outside of the current scope, consider a POCO instead. So what do we mean by intermediate results in a local context?  Well, a classic example would be filtering down results from a LINQ expression.  For example, let’s say we had a List<Transaction>, where Transaction is defined something like: 1: public class Transaction 2: { 3: public string UserId { get; set; } 4: public DateTime At { get; set; } 5: public decimal Amount { get; set; } 6: // … 7: } And let’s say we had this data in our List<Transaction>: 1: var transactions = new List<Transaction> 2: { 3: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = 2200.00m }, 4: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = -1100.00m }, 5: new Transaction { UserId = "Jim", At = DateTime.Now.AddDays(-1), Amount = 900.00m }, 6: new Transaction { UserId = "John", At = DateTime.Now.AddDays(-2), Amount = 300.00m }, 7: new Transaction { UserId = "John", At = DateTime.Now, Amount = -10.00m }, 8: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = 200.00m }, 9: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = -50.00m }, 10: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = -100.00m }, 11: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = 300.00m }, 12: }; So let’s say we wanted to get the transactions for each day for each user.  That is, for each day we’d want to see the transactions each user performed.  We could do this very simply with a nice LINQ expression, without the need of creating any POCOs: 1: // group the transactions based on an anonymous type with properties UserId and Date: 2: byUserAndDay = transactions 3: .GroupBy(tx => new { tx.UserId, tx.At.Date }) 4: .OrderBy(grp => grp.Key.Date) 5: .ThenBy(grp => grp.Key.UserId); Now, those of you who have attempted to use custom classes as a grouping type before (such as GroupBy(), Distinct(), etc.) may have discovered the hard way that LINQ gets a lot of its speed by utilizing not on Equals(), but also GetHashCode() on the type you are grouping by.  Thus, when you use custom types for these purposes, you generally end up having to write custom Equals() and GetHashCode() implementations or you won’t get the results you were expecting (the default implementations of Equals() and GetHashCode() are reference equality and reference identity based respectively). As we said before, it turns out that anonymous types already do these critical overrides for you.  This makes them even more convenient to use!  Instead of creating a small POCO to handle this grouping, and then having to implement a custom Equals() and GetHashCode() every time, we can just take advantage of the fact that anonymous types automatically override these methods with appropriate implementations that take into account the values of all of the properties. Now, we can look at our results: 1: foreach (var group in byUserAndDay) 2: { 3: // the group’s Key is an instance of our anonymous type 4: Console.WriteLine("{0} on {1:MM/dd/yyyy} did:", group.Key.UserId, group.Key.Date); 5:  6: // each grouping contains a sequence of the items. 7: foreach (var tx in group) 8: { 9: Console.WriteLine("\t{0}", tx.Amount); 10: } 11: } And see: 1: Jaime on 06/18/2012 did: 2: -100.00 3: 300.00 4:  5: John on 06/19/2012 did: 6: 300.00 7:  8: Jim on 06/20/2012 did: 9: 900.00 10:  11: Jane on 06/21/2012 did: 12: 200.00 13: -50.00 14:  15: Jim on 06/21/2012 did: 16: 2200.00 17: -1100.00 18:  19: John on 06/21/2012 did: 20: -10.00 Again, sure we could have just built a POCO to do this, given it an appropriate Equals() and GetHashCode() method, but that would have bloated our code with so many extra lines and been more difficult to maintain if the properties change.  Summary Anonymous types are one of those Little Wonders of the .NET language that are perfect at exactly that time when you need a temporary type to hold a set of properties together for an intermediate result.  While they are not very useful beyond the scope in which they are defined, they are excellent in LINQ expressions as a way to create and us intermediary values for further expressions and analysis. Anonymous types are defined by the compiler based on the number, type, names, and order of properties created, and they automatically implement appropriate Equals() and GetHashCode() overrides (as well as ToString()) which makes them ideal for LINQ expressions where you need to create a set of properties to group, evaluate, etc. Technorati Tags: C#,CSharp,.NET,Little Wonders,Anonymous Types,LINQ

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• The Inkremental Architect&acute;s Napkin - #4 - Make increments tangible

  - by Ralf Westphal

  Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/06/12/the-inkremental-architectacutes-napkin---4---make-increments-tangible.aspxThe driver of software development are increments, small increments, tiny increments. With an increment being a slice of the overall requirement scope thin enough to implement and get feedback from a product owner within 2 days max. Such an increment might concern Functionality or Quality.[1] To make such high frequency delivery of increments possible, the transition from talking to coding needs to be as easy as possible. A user story or some other documentation of what´s supposed to get implemented until tomorrow evening at latest is one side of the medal. The other is where to put the logic in all of the code base. To implement an increment, only logic statements are needed. Functionality like Quality are just about expressions and control flow statements. Think of Assembler code without the CALL/RET instructions. That´s all is needed. Forget about functions, forget about classes. To make a user happy none of that is really needed. It´s just about the right expressions and conditional executions paths plus some memory allocation. Automatic function inlining of compilers which makes it clear how unimportant functions are for delivering value to users at runtime. But why then are there functions? Because they were invented for optimization purposes. We need them for better Evolvability and Production Efficiency. Nothing more, nothing less. No software has become faster, more secure, more scalable, more functional because we gathered logic under the roof of a function or two or a thousand. Functions make logic easier to understand. Functions make us faster in producing logic. Functions make it easier to keep logic consistent. Functions help to conserve memory. That said, functions are important. They are even the pivotal element of software development. We can´t code without them - whether you write a function yourself or not. Because there´s always at least one function in play: the Entry Point of a program. In Ruby the simplest program looks like this:puts "Hello, world!" In C# more is necessary:class Program { public static void Main () { System.Console.Write("Hello, world!"); } } C# makes the Entry Point function explicit, not so Ruby. But still it´s there. So you can think of logic always running in some function. Which brings me back to increments: In order to make the transition from talking to code as easy as possible, it has to be crystal clear into which function you should put the logic. Product owners might be content once there is a sticky note a user story on the Scrum or Kanban board. But developers need an idea of what that sticky note means in term of functions. Because with a function in hand, with a signature to run tests against, they have something to focus on. All´s well once there is a function behind whose signature logic can be piled up. Then testing frameworks can be used to check if the logic is correct. Then practices like TDD can help to drive the implementation. That´s why most code katas define exactly how the API of a solution should look like. It´s a function, maybe two or three, not more. A requirement like “Write a function f which takes this as parameters and produces such and such output by doing x” makes a developer comfortable. Yes, there are all kinds of details to think about, like which algorithm or technology to use, or what kind of state and side effects to consider. Even a single function not only must deliver on Functionality, but also on Quality and Evolvability. Nevertheless, once it´s clear which function to put logic in, you have a tangible starting point. So, yes, what I´m suggesting is to find a single function to put all the logic in that´s necessary to deliver on a the requirements of an increment. Or to put it the other way around: Slice requirements in a way that each increment´s logic can be located under the roof of a single function. Entry points Of course, the logic of a software will always be spread across many, many functions. But there´s always an Entry Point. That´s the most important function for each increment, because that´s the root to put integration or even acceptance tests on. A batch program like the above hello-world application only has a single Entry Point. All logic is reached from there, regardless how deep it´s nested in classes. But a program with a user interface like this has at least two Entry Points: One is the main function called upon startup. The other is the button click event handler for “Show my score”. But maybe there are even more, like another Entry Point being a handler for the event fired when one of the choices gets selected; because then some logic could check if the button should be enabled because all questions got answered. Or another Entry Point for the logic to be executed when the program is close; because then the choices made should be persisted. You see, an Entry Point to me is a function which gets triggered by the user of a software. With batch programs that´s the main function. With GUI programs on the desktop that´s event handlers. With web programs that´s handlers for URL routes. And my basic suggestion to help you with slicing requirements for Spinning is: Slice them in a way so that each increment is related to only one Entry Point function.[2] Entry Points are the “outer functions” of a program. That´s where the environment triggers behavior. That´s where hardware meets software. Entry points always get called because something happened to hardware state, e.g. a key was pressed, a mouse button clicked, the system timer ticked, data arrived over a wire.[3] Viewed from the outside, software is just a collection of Entry Point functions made accessible via buttons to press, menu items to click, gestures, URLs to open, keys to enter. Collections of batch processors I´d thus say, we haven´t moved forward since the early days of software development. We´re still writing batch programs. Forget about “event-driven programming” with its fancy GUI applications. Software is just a collection of batch processors. Earlier it was just one per program, today it´s hundreds we bundle up into applications. Each batch processor is represented by an Entry Point as its root that works on a number of resources from which it reads data to process and to which it writes results. These resources can be the keyboard or main memory or a hard disk or a communication line or a display. Together many batch processors - large and small - form applications the user perceives as a single whole: Software development that way becomes quite simple: just implement one batch processor after another. Well, at least in principle ;-) Features Each batch processor entered through an Entry Point delivers value to the user. It´s an increment. Sometimes its logic is trivial, sometimes it´s very complex. Regardless, each Entry Point represents an increment. An Entry Point implemented thus is a step forward in terms of Agility. At the same time it´s a tangible unit for developers. Therefore, identifying the more or less numerous batch processors in a software system is a rewarding task for product owners and developers alike. That´s where user stories meet code. In this example the user story translates to the Entry Point triggered by clicking the login button on a dialog like this: The batch then retrieves what has been entered via keyboard, loads data from a user store, and finally outputs some kind of response on the screen, e.g. by displaying an error message or showing the next dialog. This is all very simple, but you see, there is not just one thing happening, but several. Get input (email address, password) Load user for email address If user not found report error Check password Hash password Compare hash to hash stored in user Show next dialog Viewed from 10,000 feet it´s all done by the Entry Point function. And of course that´s technically possible. It´s just a bunch of logic and calling a couple of API functions. However, I suggest to take these steps as distinct aspects of the overall requirement described by the user story. Such aspects of requirements I call Features. Features too are increments. Each provides some (small) value of its own to the user. Each can be checked individually by a product owner. Instead of implementing all the logic behind the Login() entry point at once you can move forward increment by increment, e.g. First implement the dialog, let the user enter any credentials, and log him/her in without any checks. Features 1 and 4. Then hard code a single user and check the email address. Features 2 and 2.1. Then check password without hashing it (or use a very simple hash like the length of the password). Features 3. and 3.2 Replace hard coded user with a persistent user directoy, but a very simple one, e.g. a CSV file. Refinement of feature 2. Calculate the real hash for the password. Feature 3.1. Switch to the final user directory technology. Each feature provides an opportunity to deliver results in a short amount of time and get feedback. If you´re in doubt whether you can implement the whole entry point function until tomorrow night, then just go for a couple of features or even just one. That´s also why I think, you should strive for wrapping feature logic into a function of its own. It´s a matter of Evolvability and Production Efficiency. A function per feature makes the code more readable, since the language of requirements analysis and design is carried over into implementation. It makes it easier to apply changes to features because it´s clear where their logic is located. And finally, of course, it lets you re-use features in different context (read: increments). Feature functions make it easier for you to think of features as Spinning increments, to implement them independently, to let the product owner check them for acceptance individually. Increments consist of features, entry point functions consist of feature functions. So you can view software as a hierarchy of requirements from broad to thin which map to a hierarchy of functions - with entry points at the top.   I like this image of software as a self-similar structure on many levels of abstraction where requirements and code match each other. That to me is true agile design: the core tenet of Agility to move forward in increments is carried over into implementation. Increments on paper are retained in code. This way developers can easily relate to product owners. Elusive and fuzzy requirements are not tangible. Software production is moving forward through requirements one increment at a time, and one function at a time. In closing Product owners and developers are different - but they need to work together towards a shared goal: working software. So their notions of software need to be made compatible, they need to be connected. The increments of the product owner - user stories and features - need to be mapped straightforwardly to something which is relevant to developers. To me that´s functions. Yes, functions, not classes nor components nor micro services. We´re talking about behavior, actions, activities, processes. Their natural representation is a function. Something has to be done. Logic has to be executed. That´s the purpose of functions. Later, classes and other containers are needed to stay on top of a growing amount of logic. But to connect developers and product owners functions are the appropriate glue. Functions which represent increments. Can there always be such a small increment be found to deliver until tomorrow evening? I boldly say yes. Yes, it´s always possible. But maybe you´ve to start thinking differently. Maybe the product owner needs to start thinking differently. Completion is not the goal anymore. Neither is checking the delivery of an increment through the user interface of a software. Product owners need to become comfortable using test beds for certain features. If it´s hard to slice requirements thin enough for Spinning the reason is too little knowledge of something. Maybe you don´t yet understand the problem domain well enough? Maybe you don´t yet feel comfortable with some tool or technology? Then it´s time to acknowledge this fact. Be honest about your not knowing. And instead of trying to deliver as a craftsman officially become a researcher. Research an check back with the product owner every day - until your understanding has grown to a level where you are able to define the next Spinning increment. ? Sometimes even thin requirement slices will cover several Entry Points, like “Add validation of email addresses to all relevant dialogs.” Validation then will it put into a dozen functons. Still, though, it´s important to determine which Entry Points exactly get affected. That´s much easier, if strive for keeping the number of Entry Points per increment to 1. ? If you like call Entry Point functions event handlers, because that´s what they are. They all handle events of some kind, whether that´s palpable in your code or note. A public void btnSave_Click(object sender, EventArgs e) {…} might look like an event handler to you, but public static void Main() {…} is one also - for then event “program started”. ?

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• Metro Walkthrough: Creating a Task List with a ListView and IndexedDB

  - by Stephen.Walther

  The goal of this blog entry is to describe how you can work with data in a Metro style application written with JavaScript. In particular, we create a super simple Task List application which enables you to create and delete tasks. Here’s a video which demonstrates how the Task List application works: In order to build this application, I had to take advantage of several features of the WinJS library and technologies including: IndexedDB – The Task List application stores data in an IndexedDB database. HTML5 Form Validation – The Task List application uses HTML5 validation to ensure that a required field has a value. ListView Control – The Task List application displays the tasks retrieved from the IndexedDB database in a WinJS ListView control. Creating the IndexedDB Database The Task List application stores all of its data in an IndexedDB database named TasksDB. This database is opened/created with the following code: var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; The msIndexedDB.open() method accepts two parameters: the name of the database to open and the version of the database to open. If a database with a matching version already exists, then calling the msIndexedDB.open() method opens a connection to the existing database. If the database does not exist then the upgradeneeded event is raised. You handle the upgradeneeded event to create a new database. In the code above, the upgradeneeded event handler creates an object store named “tasks” (An object store roughly corresponds to a database table). When you add items to the tasks object store then each item gets an id property with an auto-incremented value automatically. The code above also includes an error event handler. If the IndexedDB database cannot be opened or created, for whatever reason, then an error message is written to the Visual Studio JavaScript Console window. Displaying a List of Tasks The TaskList application retrieves its list of tasks from the tasks object store, which we created above, and displays the list of tasks in a ListView control. Here is how the ListView control is declared: <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> The ListView control is bound to the TaskList.tasks.dataSource data source. The TaskList.tasks.dataSource is created with the following code: // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); }; }; }; // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks }); Notice the success event handler. This handler is called when a database is successfully opened/created. In the code above, all of the items from the tasks object store are retrieved into a cursor and added to a WinJS.Binding.List object named tasks. Because the ListView control is bound to the WinJS.Binding.List object, copying the tasks from the object store into the WinJS.Binding.List object causes the tasks to appear in the ListView: Adding a New Task You add a new task in the Task List application by entering the title of a new task into an HTML form and clicking the Add button. Here’s the markup for creating the form: <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> Notice that the INPUT element includes a required attribute. In a Metro application, you can take advantage of HTML5 Validation to validate form fields. If you don’t enter a value for the newTaskTitle field then the following validation error message is displayed: For a brief introduction to HTML5 validation, see my previous blog entry: http://stephenwalther.com/blog/archive/2012/03/13/html5-form-validation.aspx When you click the Add button, the form is submitted and the form submit event is raised. The following code is executed in the default.js file: // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); The code above retrieves the title of the new task and calls the addTask() method in the tasks.js file. Here’s the code for the addTask() method which is responsible for actually adding the new task to the IndexedDB database: // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", "readwrite"); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } The code above does two things. First, it adds the new task to the tasks object store in the IndexedDB database. Second, it adds the new task to the data source bound to the ListView. The dataSource.insertAtEnd() method is called to add the new task to the data source so the new task will appear in the ListView (with a nice little animation). Deleting Existing Tasks The Task List application enables you to select one or more tasks by clicking or tapping on one or more tasks in the ListView. When you click the Delete button, the selected tasks are removed from both the IndexedDB database and the ListView. For example, in the following screenshot, two tasks are selected. The selected tasks appear with a teal background and a checkmark: When you click the Delete button, the following code in the default.js file is executed: // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); The selected tasks are retrieved with the TaskList selection.getItem() method. In the code above, the deleteTask() method is called for each of the selected tasks. Here’s the code for the deleteTask() method: // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", “readwrite”); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } This code does two things: it deletes the existing task from the database and removes the existing task from the ListView. In both cases, the right task is removed by using the key associated with the task. However, the task key is different in the case of the database and in the case of the ListView. In the case of the database, the task key is the value of the task id property. In the case of the ListView, on the other hand, the task key is auto-generated by the ListView. When the task is removed from the ListView, an animation is used to collapse the tasks which appear above and below the task which was removed. The Complete Code Above, I did a lot of jumping around between different files in the application and I left out sections of code. For the sake of completeness, I want to include the entire code here: the default.html, default.js, and tasks.js files. Here are the contents of the default.html file. This file contains the UI for the Task List application: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Task List</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- TaskList references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/tasks.js"></script> <style type="text/css"> body { font-size: x-large; } form { display: inline; } #appContainer { margin: 20px; width: 600px; } .win-container { padding: 10px; } </style> </head> <body> <div> <!-- Templates --> <div id="taskTemplate" data-win-control="WinJS.Binding.Template"> <div> <span data-win-bind="innerText:title"></span> </div> </div> <h1>Super Task List</h1> <div id="appContainer"> <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> <button id="btnDeleteTasks">Delete</button> <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> </div> </div> </body> </html> Here is the code for the default.js file. This code wires up the Add Task form and Delete button: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll().then(function () { // Get reference to Tasks ListView var tasksListView = document.getElementById("tasksListView"); // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); }); } }; app.start(); })(); Finally, here is the tasks.js file. This file contains all of the code for opening, creating, and interacting with IndexedDB: (function () { "use strict"; // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); }; }; }; // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", "readwrite"); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", "readwrite"); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks, addTask: addTask, deleteTask: deleteTask }); })(); Summary I wrote this blog entry because I wanted to create a walkthrough of building a simple database-driven application. In particular, I wanted to demonstrate how you can use a ListView control with an IndexedDB database to store and retrieve database data.

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• Metro Walkthrough: Creating a Task List with a ListView and IndexedDB

  - by Stephen.Walther

  The goal of this blog entry is to describe how you can work with data in a Metro style application written with JavaScript. In particular, we create a super simple Task List application which enables you to create and delete tasks. Here’s a video which demonstrates how the Task List application works: In order to build this application, I had to take advantage of several features of the WinJS library and technologies including: IndexedDB – The Task List application stores data in an IndexedDB database. HTML5 Form Validation – The Task List application uses HTML5 validation to ensure that a required field has a value. ListView Control – The Task List application displays the tasks retrieved from the IndexedDB database in a WinJS ListView control. Creating the IndexedDB Database The Task List application stores all of its data in an IndexedDB database named TasksDB. This database is opened/created with the following code: var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; The msIndexedDB.open() method accepts two parameters: the name of the database to open and the version of the database to open. If a database with a matching version already exists, then calling the msIndexedDB.open() method opens a connection to the existing database. If the database does not exist then the upgradeneeded event is raised. You handle the upgradeneeded event to create a new database. In the code above, the upgradeneeded event handler creates an object store named “tasks” (An object store roughly corresponds to a database table). When you add items to the tasks object store then each item gets an id property with an auto-incremented value automatically. The code above also includes an error event handler. If the IndexedDB database cannot be opened or created, for whatever reason, then an error message is written to the Visual Studio JavaScript Console window. Displaying a List of Tasks The TaskList application retrieves its list of tasks from the tasks object store, which we created above, and displays the list of tasks in a ListView control. Here is how the ListView control is declared: <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> The ListView control is bound to the TaskList.tasks.dataSource data source. The TaskList.tasks.dataSource is created with the following code: // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; tasks.dataSource.beginEdits(); if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); } else { tasks.dataSource.endEdits(); }; }; }; // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks }); Notice the success event handler. This handler is called when a database is successfully opened/created. In the code above, all of the items from the tasks object store are retrieved into a cursor and added to a WinJS.Binding.List object named tasks. Because the ListView control is bound to the WinJS.Binding.List object, copying the tasks from the object store into the WinJS.Binding.List object causes the tasks to appear in the ListView: Adding a New Task You add a new task in the Task List application by entering the title of a new task into an HTML form and clicking the Add button. Here’s the markup for creating the form: <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> Notice that the INPUT element includes a required attribute. In a Metro application, you can take advantage of HTML5 Validation to validate form fields. If you don’t enter a value for the newTaskTitle field then the following validation error message is displayed: For a brief introduction to HTML5 validation, see my previous blog entry: http://stephenwalther.com/blog/archive/2012/03/13/html5-form-validation.aspx When you click the Add button, the form is submitted and the form submit event is raised. The following code is executed in the default.js file: // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); The code above retrieves the title of the new task and calls the addTask() method in the tasks.js file. Here’s the code for the addTask() method which is responsible for actually adding the new task to the IndexedDB database: // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } The code above does two things. First, it adds the new task to the tasks object store in the IndexedDB database. Second, it adds the new task to the data source bound to the ListView. The dataSource.insertAtEnd() method is called to add the new task to the data source so the new task will appear in the ListView (with a nice little animation). Deleting Existing Tasks The Task List application enables you to select one or more tasks by clicking or tapping on one or more tasks in the ListView. When you click the Delete button, the selected tasks are removed from both the IndexedDB database and the ListView. For example, in the following screenshot, two tasks are selected. The selected tasks appear with a teal background and a checkmark: When you click the Delete button, the following code in the default.js file is executed: // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); The selected tasks are retrieved with the TaskList selection.getItem() method. In the code above, the deleteTask() method is called for each of the selected tasks. Here’s the code for the deleteTask() method: // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } This code does two things: it deletes the existing task from the database and removes the existing task from the ListView. In both cases, the right task is removed by using the key associated with the task. However, the task key is different in the case of the database and in the case of the ListView. In the case of the database, the task key is the value of the task id property. In the case of the ListView, on the other hand, the task key is auto-generated by the ListView. When the task is removed from the ListView, an animation is used to collapse the tasks which appear above and below the task which was removed. The Complete Code Above, I did a lot of jumping around between different files in the application and I left out sections of code. For the sake of completeness, I want to include the entire code here: the default.html, default.js, and tasks.js files. Here are the contents of the default.html file. This file contains the UI for the Task List application: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Task List</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- TaskList references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/tasks.js"></script> <style type="text/css"> body { font-size: x-large; } form { display: inline; } #appContainer { margin: 20px; width: 600px; } .win-container { padding: 10px; } </style> </head> <body> <div> <!-- Templates --> <div id="taskTemplate" data-win-control="WinJS.Binding.Template"> <div> <span data-win-bind="innerText:title"></span> </div> </div> <h1>Super Task List</h1> <div id="appContainer"> <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> <button id="btnDeleteTasks">Delete</button> <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> </div> </div> </body> </html> Here is the code for the default.js file. This code wires up the Add Task form and Delete button: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll().then(function () { // Get reference to Tasks ListView var tasksListView = document.getElementById("tasksListView"); // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); }); } }; app.start(); })(); Finally, here is the tasks.js file. This file contains all of the code for opening, creating, and interacting with IndexedDB: (function () { "use strict"; // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; tasks.dataSource.beginEdits(); if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); } else { tasks.dataSource.endEdits(); }; }; }; // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks, addTask: addTask, deleteTask: deleteTask }); })(); Summary I wrote this blog entry because I wanted to create a walkthrough of building a simple database-driven application. In particular, I wanted to demonstrate how you can use a ListView control with an IndexedDB database to store and retrieve database data.

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• Abstracting functionality

  - by Ralf Westphal

  Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/22/abstracting-functionality.aspxWhat is more important than data? Functionality. Yes, I strongly believe we should switch to a functionality over data mindset in programming. Or actually switch back to it. Focus on functionality Functionality once was at the core of software development. Back when algorithms were the first thing you heard about in CS classes. Sure, data structures, too, were important - but always from the point of view of algorithms. (Niklaus Wirth gave one of his books the title “Algorithms + Data Structures” instead of “Data Structures + Algorithms” for a reason.) The reason for the focus on functionality? Firstly, because software was and is about doing stuff. Secondly because sufficient performance was hard to achieve, and only thirdly memory efficiency. But then hardware became more powerful. That gave rise to a new mindset: object orientation. And with it functionality was devalued. Data took over its place as the most important aspect. Now discussions revolved around structures motivated by data relationships. (John Beidler gave his book the title “Data Structures and Algorithms: An Object Oriented Approach” instead of the other way around for a reason.) Sure, this data could be embellished with functionality. But nevertheless functionality was second. When you look at (domain) object models what you mostly find is (domain) data object models. The common object oriented approach is: data aka structure over functionality. This is true even for the most modern modeling approaches like Domain Driven Design. Look at the literature and what you find is recommendations on how to get data structures right: aggregates, entities, value objects. I´m not saying this is what object orientation was invented for. But I´m saying that´s what I happen to see across many teams now some 25 years after object orientation became mainstream through C++, Delphi, and Java. But why should we switch back? Because software development cannot become truly agile with a data focus. The reason for that lies in what customers need first: functionality, behavior, operations. To be clear, that´s not why software is built. The purpose of software is to be more efficient than the alternative. Money mainly is spent to get a certain level of quality (e.g. performance, scalability, security etc.). But without functionality being present, there is nothing to work on the quality of. What customers want is functionality of a certain quality. ASAP. And tomorrow new functionality needs to be added, existing functionality needs to be changed, and quality needs to be increased. No customer ever wanted data or structures. Of course data should be processed. Data is there, data gets generated, transformed, stored. But how the data is structured for this to happen efficiently is of no concern to the customer. Ask a customer (or user) whether she likes the data structured this way or that way. She´ll say, “I don´t care.” But ask a customer (or user) whether he likes the functionality and its quality this way or that way. He´ll say, “I like it” (or “I don´t like it”). Build software incrementally From this very natural focus of customers and users on functionality and its quality follows we should develop software incrementally. That´s what Agility is about. Deliver small increments quickly and often to get frequent feedback. That way less waste is produced, and learning can take place much easier (on the side of the customer as well as on the side of developers). An increment is some added functionality or quality of functionality.[1] So as it turns out, Agility is about functionality over whatever. But software developers’ thinking is still stuck in the object oriented mindset of whatever over functionality. Bummer. I guess that (at least partly) explains why Agility always hits a glass ceiling in projects. It´s a clash of mindsets, of cultures. Driving software development by demanding small increases in functionality runs against thinking about software as growing (data) structures sprinkled with functionality. (Excuse me, if this sounds a bit broad-brush. But you get my point.) The need for abstraction In the end there need to be data structures. Of course. Small and large ones. The phrase functionality over data does not deny that. It´s not functionality instead of data or something. It´s just over, i.e. functionality should be thought of first. It´s a tad more important. It´s what the customer wants. That´s why we need a way to design functionality. Small and large. We need to be able to think about functionality before implementing it. We need to be able to reason about it among team members. We need to be able to communicate our mental models of functionality not just by speaking about them, but also on paper. Otherwise reasoning about it does not scale. We learned thinking about functionality in the small using flow charts, Nassi-Shneiderman diagrams, pseudo code, or UML sequence diagrams. That´s nice and well. But it does not scale. You can use these tools to describe manageable algorithms. But it does not work for the functionality triggered by pressing the “1-Click Order” on an amazon product page for example. There are several reasons for that, I´d say. Firstly, the level of abstraction over code is negligible. It´s essentially non-existent. Drawing a flow chart or writing pseudo code or writing actual code is very, very much alike. All these tools are about control flow like code is.[2] In addition all tools are computationally complete. They are about logic which is expressions and especially control statements. Whatever you code in Java you can fully (!) describe using a flow chart. And then there is no data. They are about control flow and leave out the data altogether. Thus data mostly is assumed to be global. That´s shooting yourself in the foot, as I hope you agree. Even if it´s functionality over data that does not mean “don´t think about data”. Right to the contrary! Functionality only makes sense with regard to data. So data needs to be in the picture right from the start - but it must not dominate the thinking. The above tools fail on this. Bottom line: So far we´re unable to reason in a scalable and abstract manner about functionality. That´s why programmers are so driven to start coding once they are presented with a problem. Programming languages are the only tool they´ve learned to use to reason about functional solutions. Or, well, there might be exceptions. Mathematical notation and SQL may have come to your mind already. Indeed they are tools on a higher level of abstraction than flow charts etc. That´s because they are declarative and not computationally complete. They leave out details - in order to deliver higher efficiency in devising overall solutions. We can easily reason about functionality using mathematics and SQL. That´s great. Except for that they are domain specific languages. They are not general purpose. (And they don´t scale either, I´d say.) Bummer. So to be more precise we need a scalable general purpose tool on a higher than code level of abstraction not neglecting data. Enter: Flow Design. Abstracting functionality using data flows I believe the solution to the problem of abstracting functionality lies in switching from control flow to data flow. Data flow very naturally is not about logic details anymore. There are no expressions and no control statements anymore. There are not even statements anymore. Data flow is declarative by nature. With data flow we get rid of all the limiting traits of former approaches to modeling functionality. In addition, nomen est omen, data flows include data in the functionality picture. With data flows, data is visibly flowing from processing step to processing step. Control is not flowing. Control is wherever it´s needed to process data coming in. That´s a crucial difference and needs some rewiring in your head to be fully appreciated.[2] Since data flows are declarative they are not the right tool to describe algorithms, though, I´d say. With them you don´t design functionality on a low level. During design data flow processing steps are black boxes. They get fleshed out during coding. Data flow design thus is more coarse grained than flow chart design. It starts on a higher level of abstraction - but then is not limited. By nesting data flows indefinitely you can design functionality of any size, without losing sight of your data. Data flows scale very well during design. They can be used on any level of granularity. And they can easily be depicted. Communicating designs using data flows is easy and scales well, too. The result of functional design using data flows is not algorithms (too low level), but processes. Think of data flows as descriptions of industrial production lines. Data as material runs through a number of processing steps to be analyzed, enhances, transformed. On the top level of a data flow design might be just one processing step, e.g. “execute 1-click order”. But below that are arbitrary levels of flows with smaller and smaller steps. That´s not layering as in “layered architecture”, though. Rather it´s a stratified design à la Abelson/Sussman. Refining data flows is not your grandpa´s functional decomposition. That was rooted in control flows. Refining data flows does not suffer from the limits of functional decomposition against which object orientation was supposed to be an antidote. Summary I´ve been working exclusively with data flows for functional design for the past 4 years. It has changed my life as a programmer. What once was difficult is now easy. And, no, I´m not using Clojure or F#. And I´m not a async/parallel execution buff. Designing the functionality of increments using data flows works great with teams. It produces design documentation which can easily be translated into code - in which then the smallest data flow processing steps have to be fleshed out - which is comparatively easy. Using a systematic translation approach code can mirror the data flow design. That way later on the design can easily be reproduced from the code if need be. And finally, data flow designs play well with object orientation. They are a great starting point for class design. But that´s a story for another day. To me data flow design simply is one of the missing links of systematic lightweight software design. There are also other artifacts software development can produce to get feedback, e.g. process descriptions, test cases. But customers can be delighted more easily with code based increments in functionality. ? No, I´m not talking about the endless possibilities this opens for parallel processing. Data flows are useful independently of multi-core processors and Actor-based designs. That´s my whole point here. Data flows are good for reasoning and evolvability. So forget about any special frameworks you might need to reap benefits from data flows. None are necessary. Translating data flow designs even into plain of Java is possible. ?

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• From HttpRuntime.Cache to Windows Azure Caching (Preview)

  - by Jeff

  I don’t know about you, but the announcement of Windows Azure Caching (Preview) (yes, the parentheses are apparently part of the interim name) made me a lot more excited about using Azure. Why? Because one of the great performance tricks of any Web app is to cache frequently used data in memory, so it doesn’t have to hit the database, a service, or whatever. When you run your Web app on one box, HttpRuntime.Cache is a sweet and stupid-simple solution. Somewhere in the data fetching pieces of your app, you can see if an object is available in cache, and return that instead of hitting the data store. I did this quite a bit in POP Forums, and it dramatically cuts down on the database chatter. The problem is that it falls apart if you run the app on many servers, in a Web farm, where one server may initiate a change to that data, and the others will have no knowledge of the change, making it stale. Of course, if you have the infrastructure to do so, you can use something like memcached or AppFabric to do a distributed cache, and achieve the caching flavor you desire. You could do the same thing in Azure before, but it would cost more because you’d need to pay for another role or VM or something to host the cache. Now, you can use a portion of the memory from each instance of a Web role to act as that cache, with no additional cost. That’s huge. So if you’re using a percentage of memory that comes out to 100 MB, and you have three instances running, that’s 300 MB available for caching. For the uninitiated, a Web role in Azure is essentially a VM that runs a Web app (worker roles are the same idea, only without the IIS part). You can spin up many instances of the role, and traffic is load balanced to the various instances. It’s like adding or removing servers to a Web farm all willy-nilly and at your discretion, and it’s what the cloud is all about. I’d say it’s my favorite thing about Windows Azure. The slightly annoying thing about developing for a Web role in Azure is that the local emulator that’s launched by Visual Studio is a little on the slow side. If you’re used to using the built-in Web server, you’re used to building and then alt-tabbing to your browser and refreshing a page. If you’re just changing an MVC view, you’re not even doing the building part. Spinning up the simulated Azure environment is too slow for this, but ideally you want to code your app to use this fantastic distributed cache mechanism. So first off, here’s the link to the page showing how to code using the caching feature. If you’re used to using HttpRuntime.Cache, this should be pretty familiar to you. Let’s say that you want to use the Azure cache preview when you’re running in Azure, but HttpRuntime.Cache if you’re running local, or in a regular IIS server environment. Through the magic of dependency injection, we can get there pretty quickly. First, design an interface to handle the cache insertion, fetching and removal. Mine looks like this: public interface ICacheProvider {     void Add(string key, object item, int duration);     T Get<T>(string key) where T : class;     void Remove(string key); } Now we’ll create two implementations of this interface… one for Azure cache, one for HttpRuntime: public class AzureCacheProvider : ICacheProvider {     public AzureCacheProvider()     {         _cache = new DataCache("default"); // in Microsoft.ApplicationServer.Caching, see how-to      }         private readonly DataCache _cache;     public void Add(string key, object item, int duration)     {         _cache.Add(key, item, new TimeSpan(0, 0, 0, 0, duration));     }     public T Get<T>(string key) where T : class     {         return _cache.Get(key) as T;     }     public void Remove(string key)     {         _cache.Remove(key);     } } public class LocalCacheProvider : ICacheProvider {     public LocalCacheProvider()     {         _cache = HttpRuntime.Cache;     }     private readonly System.Web.Caching.Cache _cache;     public void Add(string key, object item, int duration)     {         _cache.Insert(key, item, null, DateTime.UtcNow.AddMilliseconds(duration), System.Web.Caching.Cache.NoSlidingExpiration);     }     public T Get<T>(string key) where T : class     {         return _cache[key] as T;     }     public void Remove(string key)     {         _cache.Remove(key);     } } Feel free to expand these to use whatever cache features you want. I’m not going to go over dependency injection here, but I assume that if you’re using ASP.NET MVC, you’re using it. Somewhere in your app, you set up the DI container that resolves interfaces to concrete implementations (Ninject call is a “kernel” instead of a container). For this example, I’ll show you how StructureMap does it. It uses a convention based scheme, where if you need to get an instance of IFoo, it looks for a class named Foo. You can also do this mapping explicitly. The initialization of the container looks something like this: ObjectFactory.Initialize(x =>             {                 x.Scan(scan =>                         {                             scan.AssembliesFromApplicationBaseDirectory();                             scan.WithDefaultConventions();                         });                 if (Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment.IsAvailable)                     x.For<ICacheProvider>().Use<AzureCacheProvider>();                 else                     x.For<ICacheProvider>().Use<LocalCacheProvider>();             }); If you use Ninject or Windsor or something else, that’s OK. Conceptually they’re all about the same. The important part is the conditional statement that checks to see if the app is running in Azure. If it is, it maps ICacheProvider to AzureCacheProvider, otherwise it maps to LocalCacheProvider. Now when a request comes into your MVC app, and the chain of dependency resolution occurs, you can see to it that the right caching code is called. A typical design may have a call stack that goes: Controller –> BusinessLogicClass –> Repository. Let’s say your repository class looks like this: public class MyRepo : IMyRepo {     public MyRepo(ICacheProvider cacheProvider)     {         _context = new MyDataContext();         _cache = cacheProvider;     }     private readonly MyDataContext _context;     private readonly ICacheProvider _cache;     public SomeType Get(int someTypeID)     {         var key = "somename-" + someTypeID;         var cachedObject = _cache.Get<SomeType>(key);         if (cachedObject != null)         {             _context.SomeTypes.Attach(cachedObject);             return cachedObject;         }         var someType = _context.SomeTypes.SingleOrDefault(p => p.SomeTypeID == someTypeID);         _cache.Add(key, someType, 60000);         return someType;     } ... // more stuff to update, delete or whatever, being sure to remove // from cache when you do so  When the DI container gets an instance of the repo, it passes an instance of ICacheProvider to the constructor, which in this case will be whatever implementation was specified when the container was initialized. The Get method first tries to hit the cache, and of course doesn’t care what the underlying implementation is, Azure, HttpRuntime, or otherwise. If it finds the object, it returns it right then. If not, it hits the database (this example is using Entity Framework), and inserts the object into the cache before returning it. The important thing not pictured here is that other methods in the repo class will construct the key for the cached object, in this case “somename-“ plus the ID of the object, and then remove it from cache, in any method that alters or deletes the object. That way, no matter what instance of the role is processing the request, it won’t find the object if it has been made stale, that is, updated or outright deleted, forcing it to attempt to hit the database. So is this good technique? Well, sort of. It depends on how you use it, and what your testing looks like around it. Because of differences in behavior and execution of the two caching providers, for example, you could see some strange errors. For example, I immediately got an error indicating there was no parameterless constructor for an MVC controller, because the DI resolver failed to create instances for the dependencies it had. In reality, the NuGet packaged DI resolver for StructureMap was eating an exception thrown by the Azure components that said my configuration, outlined in that how-to article, was wrong. That error wouldn’t occur when using the HttpRuntime. That’s something a lot of people debate about using different components like that, and how you configure them. I kinda hate XML config files, and like the idea of the code-based approach above, but you should be darn sure that your unit and integration testing can account for the differences.

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• Performance surprise with "as" and nullable types

  - by Jon Skeet

  I'm just revising chapter 4 of C# in Depth which deals with nullable types, and I'm adding a section about using the "as" operator, which allows you to write: object o = ...; int? x = o as int?; if (x.HasValue) { ... // Use x.Value in here } I thought this was really neat, and that it could improve performance over the C# 1 equivalent, using "is" followed by a cast - after all, this way we only need to ask for dynamic type checking once, and then a simple value check. This appears not to be the case, however. I've included a sample test app below, which basically sums all the integers within an object array - but the array contains a lot of null references and string references as well as boxed integers. The benchmark measures the code you'd have to use in C# 1, the code using the "as" operator, and just for kicks a LINQ solution. To my astonishment, the C# 1 code is 20 times faster in this case - and even the LINQ code (which I'd have expected to be slower, given the iterators involved) beats the "as" code. Is the .NET implementation of isinst for nullable types just really slow? Is it the additional unbox.any that causes the problem? Is there another explanation for this? At the moment it feels like I'm going to have to include a warning against using this in performance sensitive situations... Results: Cast: 10000000 : 121 As: 10000000 : 2211 LINQ: 10000000 : 2143 Code: using System; using System.Diagnostics; using System.Linq; class Test { const int Size = 30000000; static void Main() { object[] values = new object[Size]; for (int i = 0; i < Size - 2; i += 3) { values[i] = null; values[i+1] = ""; values[i+2] = 1; } FindSumWithCast(values); FindSumWithAs(values); FindSumWithLinq(values); } static void FindSumWithCast(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { if (o is int) { int x = (int) o; sum += x; } } sw.Stop(); Console.WriteLine("Cast: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithAs(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { int? x = o as int?; if (x.HasValue) { sum += x.Value; } } sw.Stop(); Console.WriteLine("As: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithLinq(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = values.OfType<int>().Sum(); sw.Stop(); Console.WriteLine("LINQ: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } }

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• Creating a Serializable mock with Mockito error

  - by KwintenP

  I'm trying to create a mock object with Mockito that can be serialized. The object is an interface implementation. When this method is called, I receive an object that I want to pass to another object, hence using the doAnswer(...)-method. This is my code. InterfaceClass obj = mock(InterfaceClass.class, withSettings().serializable()); doAnswer(new Answer<Object>() { public Object answer(InvocationOnMock invocation) throws Throwable { Object[] args = invocation.getArguments(); //Here I do something with the arguments } }).when(obj).someMethod( any(someObject.class)); ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutput out = null; try { out = new ObjectOutputStream(bos); out.writeObject(obj); byte[] yourBytes = bos.toByteArray(); } finally { out.close(); bos.close(); } As far as I can tell this should be correct (I'm fairly new to Mockito). But when Serializing my object I get this error: java.io.NotSerializableException: com.trust1t.ocs.signcore.test.InvalidInputTestCase$1 at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1165) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:329) at java.util.concurrent.ConcurrentLinkedQueue.writeObject(ConcurrentLinkedQueue.java:644) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:950) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1482) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1413) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1159) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1535) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1413) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1159) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:329) at java.util.LinkedList.writeObject(LinkedList.java:943) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:950) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1482) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1413) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1159) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1535) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1413) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1159) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1535) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1413) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1159) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1535) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1413) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1159) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1535) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1413) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1159) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:329) at com.trust1t.ocs.signcore.test.InvalidInputTestCase.certificateValidationTest(InvalidInputTestCase.java:117) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229) at org.junit.runners.ParentRunner.run(ParentRunner.java:309) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) The invalidInputTestCase class is the class containing the test where I'm using this code. It looks as if the mock object references this TestCase somewhere (can't find it though). Am I not correctly implementing this or better ideas to mock?

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• PHP parsing XML file with and without namespaces

  - by Mike

  I need to get a XML File into a Database. Thats not the problem. Cant read it, parse it and create some Objects to map to the DB. Problem is, that sometimes the XML File can contain namespaces and sometimes not. Furtermore sometimes there is no namespace defined at all. So what i first got was something like this: <?xml version="1.0" encoding="UTF-8"?> <struct xmlns:b="http://www.w3schools.com/test/"> <objects> <object> <node_1>value1</node_1> <node_2>value2</node_2> <node_3 iso_land="AFG"/> <coords lat="12.00" long="13.00"/> </object> </objects> </struct> And the parsing: $t = $xml->xpath('/objects/object'); foreach($nodes AS $node) { if($t[0]->$node) { $obj->$node = (string) $t[0]->$node; } } Thats fine as long as there are no namespaces. Here comes the XML File with namespaces: <?xml version="1.0" encoding="UTF-8"?> <b:struct xmlns:b="http://www.w3schools.com/test/"> <b:objects> <b:object> <b:node_1>value1</b:node_1> <b:node_2>value2</b:node_2> <b:node_3 iso_land="AFG"/> <b:coords lat="12.00" long="13.00"/> </b:object> </b:objects> </b:struct> I now came up with something like this: $xml = simplexml_load_file("test.xml"); $namespaces = $xml->getNamespaces(TRUE); $ns = count($namespaces) ? 'a:' : ''; $xml->registerXPathNamespace("a", "http://www.w3schools.com/test/"); $nodes = array('node_1', 'node_2'); $obj = new stdClass(); foreach($nodes AS $node) { $t = $xml->xpath('/'.$ns.'objects/'.$ns.'object/'.$ns.$node); if($t[0]) { $obj->$node = (string) $t[0]; } } $t = $xml->xpath('/'.$ns.'objects/'.$ns.'object/'.$ns.'node_3'); if($t[0]) { $obj->iso_land = (string) $t[0]->attributes()->iso_land; } $t = $xml->xpath('/'.$ns.'objects/'.$ns.'object/'.$ns.'coords'); if($t[0]) { $obj->lat = (string) $t[0]->attributes()->lat; $obj->long = (string) $t[0]->attributes()->long; } That works with namespaces and without. But i feel that there must be a better way. Before that i could do something like this: $t = $xml->xpath('/'.$ns.'objects/'.$ns.'object'); foreach($nodes AS $node) { if($t[0]->$node) { $obj->$node = (string) $t[0]->$node; } } But that just wont work with namespaces.

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• Cannot Display Chinese Character in my PHP code

  - by Jun1st

  I want to display my Twitter Info in my blog. So I write some code to get it. the issue I got is that Chinese characters displayed as unknown code. Here is the test code. Could anyone take a look and help? Thanks <html> <title>Twitter Test</title> <body> <?php function mystique_objectToArray($object){ if(!is_object($object) && !is_array($object)) return $object; if(is_object($object)) $object = get_object_vars($object); return array_map('mystique_objectToArray', $object); } define( 'ABSPATH', dirname(dirname(__FILE__)) . '/' ); require_once('/home/jun1st/jun1stfeng.com/wp-includes/class-snoopy.php'); $snoopy = new Snoopy; $response = @$snoopy->fetch("http://twitter.com/users/show/jun1st.json"); if ($response) $userdata = json_decode($snoopy->results, true); else $error = true; $response = @$snoopy->fetch("http://twitter.com/statuses/user_timeline/jun1st.json"); if ($response) $tweets = json_decode($snoopy->results, true); else $error = true; if(!$error): // for php < 5 (included JSON returns object) $userdata = mystique_objectToArray($userdata); $tweets = mystique_objectToArray($tweets); $twitdata = array(); $twitdata['user']['profile_image_url'] = $userdata['profile_image_url']; $twitdata['user']['name'] = $userdata['name']; $twitdata['user']['screen_name'] = $userdata['screen_name']; $twitdata['user']['followers_count'] = $userdata['followers_count']; $i = 0; foreach($tweets as $tweet): $twitdata['tweets'][$i]['text'] = $tweet['text']; $twitdata['tweets'][$i]['created_at'] = $tweet['created_at']; $twitdata['tweets'][$i]['id'] = $tweet['id']; $i++; endforeach; endif; // only show if the twitter data from the database is newer than 6 hours if(is_array($twitdata['tweets'])): ?> <div class="clear-block"> <div class="avatar"><img src="<?php echo $twitdata['user']['profile_image_url']; ?>" alt="<?php echo $twitdata['user']['name']; ?>" /></div> <div class="info"><a href="http://www.twitter.com/jun1st"><?php echo $twitdata['user']['name']; ?> </a><br /><span class="followers"> <?php printf(__("%s followers","mystique"),$twitdata['user']['followers_count']); ?></span></div> </div> <ul> <?php $i = 0; foreach($twitdata['tweets'] as $tweet): $pattern = '/\@(\w+)/'; $replace = '<a rel="nofollow" href="http://twitter.com/$1">@$1</a>'; $tweet['text'] = preg_replace($pattern, $replace , $tweet['text']); $tweet['text'] = make_clickable($tweet['text']); // remove +XXXX $tweettime = substr_replace($tweet['created_at'],'',strpos($tweet['created_at'],"+"),5); $link = "http://twitter.com/".$twitdata['user']['screen_name']."/statuses/".$tweet['id']; echo '<li><span class="entry">' . $tweet['text'] .'<a class="date" href="'.$link.'" rel="nofollow">'.$tweettime.'</a></span></li>'; $i++; if ($i == $twitcount) break; endforeach; ?> </ul> <? endif?> ?> </body> </html>

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• How can I bind events to strongly typed datasets of different types?

  My application contains several forms which consist of a strongly typed datagridview, a strongly typed bindingsource, and a strongly typed table adapter. I am using some code in each form to update the database whenever the user leaves the current row, shifts focus away from the datagrid or the form, or closes the form. This code is the same in each case, so I want to make a subclass of form, from which all of these forms can inherit. But the strongly typed data objects all inherit from component, which doesn't expose the events I want to bind to or the methods I want to invoke. The only way I can see of gaining access to the events is to use: Type(string Name).GetEvent(string EventName).AddEventHandler(object Target,Delegate Handler) Similarly, I want to call the Update method of the strongly typed table adapter, and am using Type(string Name).GetMethod(String name, Type[] params).Invoke(object target, object[] params). It works ok, but it seems very heavy handed. Is there a better way? Here is my code for the main class: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows.Forms; using System.Data; using System.Data.SqlClient; using System.ComponentModel; namespace MyApplication { public class AutoSaveDataGridForm: Form { private DataRow PreviousRow; public Component Adapter { private get; set; } private Component dataGridView; public Component DataGridView { private get { return dataGridView; } set { dataGridView = value; Type t = dataGridView.GetType(); t.GetEvent("Leave").AddEventHandler(dataGridView, new EventHandler(DataGridView_Leave)); } } private Component bindingSource; public Component BindingSource { private get { return bindingSource; } set { bindingSource = value; Type t = bindingSource.GetType(); t.GetEvent("PositionChanged").AddEventHandler(bindingSource, new EventHandler(BindingSource_PositionChanged)); } } protected void Save() { if (PreviousRow != null && PreviousRow.RowState != DataRowState.Unchanged) { Type t = Adapter.GetType(); t.GetMethod("Update", new Type[] { typeof(DataRow[]) }).Invoke(Adapter, new object[] { new DataRow[] { PreviousRow } }); } } private void BindingSource_PositionChanged(object sender, EventArgs e) { BindingSource bindingSource = sender as BindingSource; DataRowView CurrentRowView = bindingSource.Current as DataRowView; DataRow CurrentRow = CurrentRowView.Row; if (PreviousRow != null && PreviousRow != CurrentRow) { Save(); } PreviousRow = CurrentRow; } private void InitializeComponent() { this.SuspendLayout(); // // AutoSaveDataGridForm // this.FormClosed += new System.Windows.Forms.FormClosedEventHandler(this.AutoSaveDataGridForm_FormClosed); this.Leave += new System.EventHandler(this.AutoSaveDataGridForm_Leave); this.ResumeLayout(false); } private void DataGridView_Leave(object sender, EventArgs e) { Save(); } private void AutoSaveDataGridForm_FormClosed(object sender, FormClosedEventArgs e) { Save(); } private void AutoSaveDataGridForm_Leave(object sender, EventArgs e) { Save(); } } } And here is a (partial) form which implements it: public partial class FileTypesInherited :AutoSaveDataGridForm { public FileTypesInherited() { InitializeComponent(); } private void FileTypesInherited_Load(object sender, EventArgs e) { // TODO: This line of code loads data into the 'sharedFoldersInformationV2DataSet.tblFileTypes' table. You can move, or remove it, as needed. this.tblFileTypesTableAdapter.Fill(this.sharedFoldersInformationV2DataSet.tblFileTypes); this.BindingSource = tblFileTypesBindingSource; this.Adapter = tblFileTypesTableAdapter; this.DataGridView = tblFileTypesDataGridView; } }

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• globals and locals in python exec()

  - by hawkettc

  Hi, I'm trying to run a piece of python code using exec. my_code = """ class A(object): pass print 'locals: %s' % locals() print 'A: %s' % A class B(object): a_ref = A """ global_env = {} local_env = {} my_code_AST = compile(my_code, "My Code", "exec") exec(my_code_AST, global_env, local_env) print local_env which results in the following output locals: {'A': <class 'A'>} A: <class 'A'> Traceback (most recent call last): File "python_test.py", line 16, in <module> exec(my_code_AST, global_env, local_env) File "My Code", line 8, in <module> File "My Code", line 9, in B NameError: name 'A' is not defined However, if I change the code to this - my_code = """ class A(object): pass print 'locals: %s' % locals() print 'A: %s' % A class B(A): pass """ global_env = {} local_env = {} my_code_AST = compile(my_code, "My Code", "exec") exec(my_code_AST, global_env, local_env) print local_env then it works fine - giving the following output - locals: {'A': <class 'A'>} A: <class 'A'> {'A': <class 'A'>, 'B': <class 'B'>} Clearly A is present and accessible - what's going wrong in the first piece of code? I'm using 2.6.5, cheers, Colin * UPDATE 1 * If I check the locals() inside the class - my_code = """ class A(object): pass print 'locals: %s' % locals() print 'A: %s' % A class B(object): print locals() a_ref = A """ global_env = {} local_env = {} my_code_AST = compile(my_code, "My Code", "exec") exec(my_code_AST, global_env, local_env) print local_env Then it becomes clear that locals() is not the same in both places - locals: {'A': <class 'A'>} A: <class 'A'> {'__module__': '__builtin__'} Traceback (most recent call last): File "python_test.py", line 16, in <module> exec(my_code_AST, global_env, local_env) File "My Code", line 8, in <module> File "My Code", line 10, in B NameError: name 'A' is not defined However, if I do this, there is no problem - def f(): class A(object): pass class B(object): a_ref = A f() print 'Finished OK' * UPDATE 2 * ok, so the docs here - http://docs.python.org/reference/executionmodel.html 'A class definition is an executable statement that may use and define names. These references follow the normal rules for name resolution. The namespace of the class definition becomes the attribute dictionary of the class. Names defined at the class scope are not visible in methods.' It seems to me that 'A' should be made available as a free variable within the executable statement that is the definition of B, and this happens when we call f(), but not when we use exec(). This can be more easily shown with the following - my_code = """ class A(object): pass print 'locals in body: %s' % locals() print 'A: %s' % A def f(): print 'A in f: %s' % A f() class B(object): a_ref = A """ which outputs locals in body: {'A': <class 'A'>} A: <class 'A'> Traceback (most recent call last): File "python_test.py", line 20, in <module> exec(my_code_AST, global_env, local_env) File "My Code", line 11, in <module> File "My Code", line 9, in f NameError: global name 'A' is not defined So I guess the new question is - why aren't those locals being exposed as free variables in functions and class definitions - it seems like a pretty standard closure scenario.

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• Java JNI leak in c++ process.

  - by user662056

  Hi all.. I am beginner in Java. My problem is: I am calling a Java class's method from c++. For this i am using JNI. Everythings works correct, but i have some memory LEAKS in the process of c++ program... So.. i did simple example.. 1) I create a java machine (jint res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);) 2) then i take a pointer on java class (jclass cls = env-FindClass("test_jni")); 3) after that i create a java class object object, by calling the constructor (testJavaObject = env-NewObject(cls, testConstruct);) AT THIS very moment in the process of c++ program is allocated 10 MB of memory 4) Next i delete the class , the object, and the Java Machine .. AT THIS very moment the 10 MB of memory are not free ................. So below i have a few lines of code c++ program void main() { { //Env JNIEnv *env; // java virtual machine JavaVM *jvm; JavaVMOption* options = new JavaVMOption[1]; //class paths options[0].optionString = "-Djava.class.path=C:/Sun/SDK/jdk/lib;D:/jms_test/java_jni_leak;"; // other options JavaVMInitArgs vm_args; vm_args.version = JNI_VERSION_1_6; vm_args.options = options; vm_args.nOptions = 1; vm_args.ignoreUnrecognized = false; // alloc part of memory (for test) before CreateJavaVM char* testMem0 = new char[1000]; for(int i = 0; i < 1000; ++i) testMem0[i] = 'a'; // create java VM jint res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args); // alloc part of memory (for test) after CreateJavaVM char* testMem1 = new char[1000]; for(int i = 0; i < 1000; ++i) testMem1[i] = 'b'; //Creating java virtual machine jclass cls = env->FindClass("test_jni"); // Id of a class constructor jmethodID testConstruct = env->GetMethodID(cls, "<init>", "()V"); // The Java Object // Calling the constructor, is allocated 10 MB of memory in c++ process jobject testJavaObject = env->NewObject(cls, testConstruct); // function DeleteLocalRef, // In this very moment memory not free env->DeleteLocalRef(testJavaObject); env->DeleteLocalRef(cls); // 1!!!!!!!!!!!!! res = jvm->DestroyJavaVM(); delete[] testMem0; delete[] testMem1; // In this very moment memory not free. TO /// } int gg = 0; } java class (it just allocs some memory) import java.util.*; public class test_jni { ArrayList<String> testStringList; test_jni() { System.out.println("start constructor"); testStringList = new ArrayList<String>(); for(int i = 0; i < 1000000; ++i) { // ??????? ?????? testStringList.add("TEEEEEEEEEEEEEEEEST"); } } } process memory view, after crating javaVM and java object: testMem0 and testMem1 - test memory, that's allocated by c++. ************** testMem0 ************** JNI_CreateJavaVM ************** testMem1 ************** // create java object jobject testJavaObject = env->NewObject(cls, testConstruct); ************** process memory view, after destroy javaVM and delete ref on java object: testMem0 and testMem1 are deleted to; ************** JNI_CreateJavaVM ************** // create java object jobject testJavaObject = env->NewObject(cls, testConstruct); ************** So testMem0 and testMem1 is deleted, But JavaVM and Java object not.... Sow what i do wrong... and how i can free memory in the c++ process program.

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• CodePlex Daily Summary for Friday, May 07, 2010

  CodePlex Daily Summary for Friday, May 07, 2010New ProjectsBibleBrowser: BibleBrowserBibleMaps: BibleMapsChristianLibrary: ChristianLibraryCLB Podcast Module: DotNetNuke Module used to allow DNN to host one or more podcasts within a portal.Coletivo InVitro: Nova versão do Site do ColetivoCustomer Care Accelerator for Microsoft Dynamics CRM: Customer Care Accelerator for Microsoft Dynamics CRM.EasyTFS: A very lightweight, quick, web-based search application for Team Foundation Server. EasyTfs searches as you type, providing real-time search resul...FSCommunity: abcGeocache Downloader: GeocacheDownloader helps you download geocache information in an organised way, making easier to copy the information to your device. The applicati...Grabouille: Grabouille aims to be an incubation project for Microsoft best patterns & practices and also a container for last .Net technologies. The goal is, i...Klaverjas: Test application for testing different new technologies in .NET (WCF, DataServices, C# stuff, Entity...etc.)Livecity: Social network. Alpha 0.1MarxSupples: testMOSS 2007 - Excel Services: This helps you understand MOSS 2007 - Excel Services and how to use the same in .NETmy site: a personal web siteNazTek.Extension.Clr35: Contains a set of CLR 3.5 extensions and utility APInetDumbster: netDumbster is a .Net Fake SMTP Server clone of the popular Dumbster (http://quintanasoft.com/dumbster/) netDumbster is based on the API of nDumbs...Object-Oriented Optimization Toolbox (OOOT): A library (.dll) of various linear, nonlinear, and stochastic numerical optimization techniques. While some of these are older than 50 years, they ...OMap - Object to Object Mapper: OMap is a simple object to object mapper. It could be used for scenarios like mapping your data from domain objects into data transfer objects.PDF Renderer for BlackBerry.: Render and view PDF files on BlackBerry using a modified version of Sun's PDF Renderer.Pomodoro Tool: Pomodoro Tool is a timer for http://www.pomodorotechnique.com/ . It's a timer and task tracker with a text task editing interface.ReadingPlan: ReadingPlanRil#: .net library to use the public Readitlater.com public APISCSM Incident SLA Management: This project provides an extension to System Center Service Manager to provide more granular control over incident service level agreement (SLA) ma...SEAH - Sistema Especialista de Agravante de Hipertensão: O SEAH tem como propósito alertar o indivíduo em relação ao seu agravante de hipertensão arterial e a órgãos competentes, entidades de ensino, pesq...StudyGuide: StudyGuideTest Project (ignore): This is used to demonstrate CodePlex at meetings. Please ignore this project.YCC: YCC is an open source c compiler which compatible with ANSI standard.The project is currently an origin start.We will work it for finally useable a...New ReleasesAlbum photo de club - Club's Photos Album: App - version 0.5: Modifications : - Ajout des favoris - Ajout de l'update automatique /*/ - Add favorites - Add automatic updateBoxee Launcher: Boxee Launcher 1.0.1.5: Boxee Launcher finds the BOXEE executable using a registry key that BOXEE creates. The new version of BOXEE changed the location. Boxee Launcher ha...CBM-Command: 2010-05-06: Release Notes - 2010-05-06New Features Creating Directories Deleting Files and Directories Renaming Files and Directories Changes 40 columns i...Customer Care Accelerator for Microsoft Dynamics CRM: Customer Care Accelerator for Dynamics CRM R1: The Customer Care Accelerator (CCA) for Microsoft Dynamics CRM focuses on delivering contact center enabling functionality, such as the ability to ...D-AMPS: D-AMPS 0.9.2: Add .bat files for command-line running Bug fixed (core engine) Section 6, 8, 9 modifications Sources (Fortran) for core engineDynamicJson: Release 1.1.0.0: Add - foreach support Add - Dynamic Shortcut of IsDefined,Delete,Deserialize Fix - Deserialize Delete - LengthEasyTFS: EasyTfs 1.0 Beta 1: A very lightweight, quick, web-based search application for Team Foundation Server. EasyTfs searches as you type, providing real-time search resul...Event Scavenger: Add installer for Admin tool: Added installer for Admin tool. Removed exe's for admin and viewer from zip file - were replaced by the msi installers.Expression Blend Samples: PathListBoxUtils for Expression Blend 4 RC: Initial release of the PathListBoxUtils samples.HackingSilverlight Code Browser: HackingSilverlight Code Browser: Out with the old and in with the new... the HackingSilverlight Code Browser is a reference tool for code snippets so that I can not have to remembe...Hammock for REST: Hammock v1.0.3: v1.0.3 ChangesFixes for OAuth escaping and API usage Added FollowRedirects feature to RestClient/RestRequest v1.0.2 Changes.NET 4.0 and Client P...ImmlPad: ImmlPad Beta 1.1.1: Changes in this release: Added more intelligent right-click menu's to allow opening an IMML document with a specific Player version Fixed issue w...LinkedIn® for Windows Mobile: LinkedIn for Windows Mobile v0.8: Improved error message dumping + moved OAuth parameters from www.* to api.* In case of unexpected errors, check "Application Data\LinkedIn for Wind...Live-Exchange Calendar Sync: Installer: Alpha release of Live-Exchange Calendar SyncMAPILab Explorer for SharePoint: MAPILab Explorer for SharePoint ver 2.1.0: 1) Get settings form old versions 2) Rules added to display enumerable object items. 3) Bug fixed with remove persisted object How to install:Do...MapWindow6: MapWindow 6.0 msi May 6, 2010: This release enables output .prj files to also show the ESRI names for the PRJCS, GEOCS, and the DATUM. It also fixes a bug that was preventing th...MOSS 2007 - Excel Services: Calculator using Excel Services: Simple calculator using Excel ServicesMvcMaps - Unified Bing/Google Mapping API for ASP.NET MVC: MvcMaps Preview 1 for ASP.NET 4.0 and VS'2010: There was a change in ASP.NET 4.0 that broke the release, so a small modification needed to be made to the reflection code. This release fixes that...NazTek.Extension.Clr35: NazTek.Extension.Clr35 Binary Cab: Binary cab fileNazTek.Extension.Clr35: NazTek.Extension.Clr35 Source Cab: Source codePDF Renderer for BlackBerry.: PDF Renderer 0.1 for BlackBerry: This library requires a BlackBerry Signing Key in order to compile for use on a BlackBerry device. Signing keys can be obtained at BlackBerry Code ...Pomodoro Tool: PomodoroTool Clickonce installer: PomodoroTool Clickonce installerPOS for .Net Handheld Products Service Object: POS for .Net Handheld Products Service Object 1002: New version (1.0.0.2) which should support 64 bit platforms (see ReadMe.txt included with source for details). Source code only.QuestTracker: QuestTracker 0.4: What's New in QuestTracker 0.4 - - You can now drag and drop the quests on the left pane to rearrange or move quests from one group to another. - D...RDA Collaboration Team Projects: Property Bag Cmdlet: This cmdlet allows to retrieve, insert and update property bag values at farm, web app, site and web scope. The same operations can be in code usi...Ril#: Rilsharp 1.0: The first version of the Ril# (Readitlater sharp) library.Scrum Sprint Monitor: v1.0.0.47911 (.NET 4-TFS 2010): What is new in this release? Migrated to .NET Framework 4 RTM; Compiled against TFS 2010 RTM Client DLLs; Smoother animations with easing funct...SCSM Incident SLA Management: SCSM Incident SLA Management Version 0.1: This is the first release of the SCSM SLA Management solution. It is an 'alpha' release and has only been tested by the developers on the project....StackOverflow Desktop Client in C# and WPF: StackOverflow Client 0.4: Shows a popup that displays all the new questions and allows you to navigate between them. Fixed a bug that showed incorrect views and answers in t...Transcriber: Transcriber V0.1: Pre-release, usable but very rough.VCC: Latest build, v2.1.30506.0: Automatic drop of latest buildVisual Studio CSLA Extension for ADO.NET Entity Framework: CslaExtension Beta1: Requirements Visual Studio 2010 CSLA 4.0. Beta 1 Installation Download VSIX file and double click to install. Open Visual Studio -> Tools -> Exte...Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight Toolkitpatterns & practices – Enterprise LibraryWindows Presentation Foundation (WPF)ASP.NETDotNetNuke® Community EditionMicrosoft SQL Server Community & SamplesMost Active Projectspatterns & practices – Enterprise LibraryAJAX Control FrameworkIonics Isapi Rewrite FilterRawrpatterns & practices: Azure Security GuidanceCaliburn: An Application Framework for WPF and SilverlightBlogEngine.NETTweetSharpNB_Store - Free DotNetNuke Ecommerce Catalog ModuleTinyProject

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• C#/.NET Little Wonders: Constraining Generics with Where Clause

  - by James Michael Hare

  Back when I was primarily a C++ developer, I loved C++ templates.  The power of writing very reusable generic classes brought the art of programming to a brand new level.  Unfortunately, when .NET 1.0 came about, they didn’t have a template equivalent.  With .NET 2.0 however, we finally got generics, which once again let us spread our wings and program more generically in the world of .NET However, C# generics behave in some ways very differently from their C++ template cousins.  There is a handy clause, however, that helps you navigate these waters to make your generics more powerful. The Problem – C# Assumes Lowest Common Denominator In C++, you can create a template and do nearly anything syntactically possible on the template parameter, and C++ will not check if the method/fields/operations invoked are valid until you declare a realization of the type.  Let me illustrate with a C++ example: 1: // compiles fine, C++ makes no assumptions as to T 2: template <typename T> 3: class ReverseComparer 4: { 5: public: 6: int Compare(const T& lhs, const T& rhs) 7: { 8: return rhs.CompareTo(lhs); 9: } 10: }; Notice that we are invoking a method CompareTo() off of template type T.  Because we don’t know at this point what type T is, C++ makes no assumptions and there are no errors. C++ tends to take the path of not checking the template type usage until the method is actually invoked with a specific type, which differs from the behavior of C#: 1: // this will NOT compile! C# assumes lowest common denominator. 2: public class ReverseComparer<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } So why does C# give us a compiler error even when we don’t yet know what type T is?  This is because C# took a different path in how they made generics.  Unless you specify otherwise, for the purposes of the code inside the generic method, T is basically treated like an object (notice I didn’t say T is an object). That means that any operations, fields, methods, properties, etc that you attempt to use of type T must be available at the lowest common denominator type: object.  Now, while object has the broadest applicability, it also has the fewest specific.  So how do we allow our generic type placeholder to do things more than just what object can do? Solution: Constraint the Type With Where Clause So how do we get around this in C#?  The answer is to constrain the generic type placeholder with the where clause.  Basically, the where clause allows you to specify additional constraints on what the actual type used to fill the generic type placeholder must support. You might think that narrowing the scope of a generic means a weaker generic.  In reality, though it limits the number of types that can be used with the generic, it also gives the generic more power to deal with those types.  In effect these constraints says that if the type meets the given constraint, you can perform the activities that pertain to that constraint with the generic placeholders. Constraining Generic Type to Interface or Superclass One of the handiest where clause constraints is the ability to specify the type generic type must implement a certain interface or be inherited from a certain base class. For example, you can’t call CompareTo() in our first C# generic without constraints, but if we constrain T to IComparable<T>, we can: 1: public class ReverseComparer<T> 2: where T : IComparable<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } Now that we’ve constrained T to an implementation of IComparable<T>, this means that our variables of generic type T may now call any members specified in IComparable<T> as well.  This means that the call to CompareTo() is now legal. If you constrain your type, also, you will get compiler warnings if you attempt to use a type that doesn’t meet the constraint.  This is much better than the syntax error you would get within C++ template code itself when you used a type not supported by a C++ template. Constraining Generic Type to Only Reference Types Sometimes, you want to assign an instance of a generic type to null, but you can’t do this without constraints, because you have no guarantee that the type used to realize the generic is not a value type, where null is meaningless. Well, we can fix this by specifying the class constraint in the where clause.  By declaring that a generic type must be a class, we are saying that it is a reference type, and this allows us to assign null to instances of that type: 1: public static class ObjectExtensions 2: { 3: public static TOut Maybe<TIn, TOut>(this TIn value, Func<TIn, TOut> accessor) 4: where TOut : class 5: where TIn : class 6: { 7: return (value != null) ? accessor(value) : null; 8: } 9: } In the example above, we want to be able to access a property off of a reference, and if that reference is null, pass the null on down the line.  To do this, both the input type and the output type must be reference types (yes, nullable value types could also be considered applicable at a logical level, but there’s not a direct constraint for those). Constraining Generic Type to only Value Types Similarly to constraining a generic type to be a reference type, you can also constrain a generic type to be a value type.  To do this you use the struct constraint which specifies that the generic type must be a value type (primitive, struct, enum, etc). Consider the following method, that will convert anything that is IConvertible (int, double, string, etc) to the value type you specify, or null if the instance is null. 1: public static T? ConvertToNullable<T>(IConvertible value) 2: where T : struct 3: { 4: T? result = null; 5:  6: if (value != null) 7: { 8: result = (T)Convert.ChangeType(value, typeof(T)); 9: } 10:  11: return result; 12: } Because T was constrained to be a value type, we can use T? (System.Nullable<T>) where we could not do this if T was a reference type. Constraining Generic Type to Require Default Constructor You can also constrain a type to require existence of a default constructor.  Because by default C# doesn’t know what constructors a generic type placeholder does or does not have available, it can’t typically allow you to call one.  That said, if you give it the new() constraint, it will mean that the type used to realize the generic type must have a default (no argument) constructor. Let’s assume you have a generic adapter class that, given some mappings, will adapt an item from type TFrom to type TTo.  Because it must create a new instance of type TTo in the process, we need to specify that TTo has a default constructor: 1: // Given a set of Action<TFrom,TTo> mappings will map TFrom to TTo 2: public class Adapter<TFrom, TTo> : IEnumerable<Action<TFrom, TTo>> 3: where TTo : class, new() 4: { 5: // The list of translations from TFrom to TTo 6: public List<Action<TFrom, TTo>> Translations { get; private set; } 7:  8: // Construct with empty translation and reverse translation sets. 9: public Adapter() 10: { 11: // did this instead of auto-properties to allow simple use of initializers 12: Translations = new List<Action<TFrom, TTo>>(); 13: } 14:  15: // Add a translator to the collection, useful for initializer list 16: public void Add(Action<TFrom, TTo> translation) 17: { 18: Translations.Add(translation); 19: } 20:  21: // Add a translator that first checks a predicate to determine if the translation 22: // should be performed, then translates if the predicate returns true 23: public void Add(Predicate<TFrom> conditional, Action<TFrom, TTo> translation) 24: { 25: Translations.Add((from, to) => 26: { 27: if (conditional(from)) 28: { 29: translation(from, to); 30: } 31: }); 32: } 33:  34: // Translates an object forward from TFrom object to TTo object. 35: public TTo Adapt(TFrom sourceObject) 36: { 37: var resultObject = new TTo(); 38:  39: // Process each translation 40: Translations.ForEach(t => t(sourceObject, resultObject)); 41:  42: return resultObject; 43: } 44:  45: // Returns an enumerator that iterates through the collection. 46: public IEnumerator<Action<TFrom, TTo>> GetEnumerator() 47: { 48: return Translations.GetEnumerator(); 49: } 50:  51: // Returns an enumerator that iterates through a collection. 52: IEnumerator IEnumerable.GetEnumerator() 53: { 54: return GetEnumerator(); 55: } 56: } Notice, however, you can’t specify any other constructor, you can only specify that the type has a default (no argument) constructor. Summary The where clause is an excellent tool that gives your .NET generics even more power to perform tasks higher than just the base "object level" behavior.  There are a few things you cannot specify with constraints (currently) though: Cannot specify the generic type must be an enum. Cannot specify the generic type must have a certain property or method without specifying a base class or interface – that is, you can’t say that the generic must have a Start() method. Cannot specify that the generic type allows arithmetic operations. Cannot specify that the generic type requires a specific non-default constructor. In addition, you cannot overload a template definition with different, opposing constraints.  For example you can’t define a Adapter<T> where T : struct and Adapter<T> where T : class.  Hopefully, in the future we will get some of these things to make the where clause even more useful, but until then what we have is extremely valuable in making our generics more user friendly and more powerful!   Technorati Tags: C#,.NET,Little Wonders,BlackRabbitCoder,where,generics

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• Developing Schema Compare for Oracle (Part 2): Dependencies

  - by Simon Cooper

  In developing Schema Compare for Oracle, one of the issues we came across was the size of the databases. As detailed in my last blog post, we had to allow schema pre-filtering due to the number of objects in a standard Oracle database. Unfortunately, this leads to some quite tricky situations regarding object dependencies. This post explains how we deal with these dependencies. 1. Cross-schema dependencies Say, in the following database, you're populating SchemaA, and synchronizing SchemaA.Table1: SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(Col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100) REFERENCES SchemaB.Table1(Col1)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100) PRIMARY KEY); We need to do a rebuild of SchemaA.Table1 to change Col1 from a VARCHAR2(100) to a NUMBER. This consists of: Creating a table with the new schema Inserting data from the old table to the new table, with appropriate conversion functions (in this case, TO_NUMBER) Dropping the old table Rename new table to same name as old table Unfortunately, in this situation, the rebuild will fail at step 1, as we're trying to create a NUMBER column with a foreign key reference to a VARCHAR2(100) column. As we're only populating SchemaA, the naive implementation of the object population prefiltering (sticking a WHERE owner = 'SCHEMAA' on all the data dictionary queries) will generate an incorrect sync script. What we actually have to do is: Drop foreign key constraint on SchemaA.Table1 Rebuild SchemaB.Table1 Rebuild SchemaA.Table1, adding the foreign key constraint to the new table This means that in order to generate a correct synchronization script for SchemaA.Table1 we have to know what SchemaB.Table1 is, and that it also needs to be rebuilt to successfully rebuild SchemaA.Table1. SchemaB isn't the schema that the user wants to synchronize, but we still have to load the table and column information for SchemaB.Table1 the same way as any table in SchemaA. Fortunately, Oracle provides (mostly) complete dependency information in the dictionary views. Before we actually read the information on all the tables and columns in the database, we can get dependency information on all the objects that are either pointed at by objects in the schemas we’re populating, or point to objects in the schemas we’re populating (think about what would happen if SchemaB was being explicitly populated instead), with a suitable query on all_constraints (for foreign key relationships) and all_dependencies (for most other types of dependencies eg a function using another function). The extra objects found can then be included in the actual object population, and the sync wizard then has enough information to figure out the right thing to do when we get to actually synchronize the objects. Unfortunately, this isn’t enough. 2. Dependency chains The solution above will only get the immediate dependencies of objects in populated schemas. What if there’s a chain of dependencies? A.tbl1 -> B.tbl1 -> C.tbl1 -> D.tbl1 If we’re only populating SchemaA, the implementation above will only include B.tbl1 in the dependent objects list, whereas we might need to know about C.tbl1 and D.tbl1 as well, in order to ensure a modification on A.tbl1 can succeed. What we actually need is a graph traversal on the dependency graph that all_dependencies represents. Fortunately, we don’t have to read all the database dependency information from the server and run the graph traversal on the client computer, as Oracle provides a method of doing this in SQL – CONNECT BY. So, we can put all the dependencies we want to include together in big bag with UNION ALL, then run a SELECT ... CONNECT BY on it, starting with objects in the schema we’re populating. We should end up with all the objects that might be affected by modifications in the initial schema we’re populating. Good solution? Well, no. For one thing, it’s sloooooow. all_dependencies, on my test databases, has got over 110,000 rows in it, and the entire query, for which Oracle was creating a temporary table to hold the big bag of graph edges, was often taking upwards of two minutes. This is too long, and would only get worse for large databases. But it had some more fundamental problems than just performance. 3. Comparison dependencies Consider the following schema: SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100)); What will happen if we used the dependency algorithm above on the source & target database? Well, SchemaA.Table1 has a foreign key reference to SchemaB.Table1, so that will be included in the source database population. On the target, SchemaA.Table1 has no such reference. Therefore SchemaB.Table1 will not be included in the target database population. In the resulting comparison of the two objects models, what you will end up with is: SOURCE  TARGET SchemaA.Table1 -> SchemaA.Table1 SchemaB.Table1 -> (no object exists) When this comparison is synchronized, we will see that SchemaB.Table1 does not exist, so we will try the following sequence of actions: Create SchemaB.Table1 Rebuild SchemaA.Table1, with foreign key to SchemaB.Table1 Oops. Because the dependencies are only followed within a single database, we’ve tried to create an object that already exists. To fix this we can include any objects found as dependencies in the source or target databases in the object population of both databases. SchemaB.Table1 will then be included in the target database population, and we won’t try and create objects that already exist. All good? Well, consider the following schema (again, only explicitly populating SchemaA, and synchronizing SchemaA.Table1): SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100) PRIMARY KEY); CREATE TABLE SchemaC.Table1 ( Col1 NUMBER);   CREATE TABLE SchemaC.Table1 ( Col1 VARCHAR2(100) REFERENCES SchemaB.Table1); Although we’re now including SchemaB.Table1 on both sides of the comparison, there’s a third table (SchemaC.Table1) that we don’t know about that will cause the rebuild of SchemaB.Table1 to fail if we try and synchronize SchemaA.Table1. That’s because we’re only running the dependency query on the schemas we’re explicitly populating; to solve this issue, we would have to run the dependency query again, but this time starting the graph traversal from the objects found in the other database. Furthermore, this dependency chain could be arbitrarily extended.This leads us to the following algorithm for finding all the dependencies of a comparison: Find initial dependencies of schemas the user has selected to compare on the source and target Include these objects in both the source and target object populations Run the dependency query on the source, starting with the objects found as dependents on the target, and vice versa Repeat 2 & 3 until no more objects are found For the schema above, this will result in the following sequence of actions: Find initial dependenciesSchemaA.Table1 -> SchemaB.Table1 found on sourceNo objects found on target Include objects in both source and targetSchemaB.Table1 included in source and target Run dependency query, starting with found objectsNo objects to start with on sourceSchemaB.Table1 -> SchemaC.Table1 found on target Include objects in both source and targetSchemaC.Table1 included in source and target Run dependency query on found objectsNo objects found in sourceNo objects to start with in target Stop This will ensure that we include all the necessary objects to make any synchronization work. However, there is still the issue of query performance; the CONNECT BY on the entire database dependency graph is still too slow. After much sitting down and drawing complicated diagrams, we decided to move the graph traversal algorithm from the server onto the client (which turned out to run much faster on the client than on the server); and to ensure we don’t read the entire dependency graph onto the client we also pull the graph across in bits – we start off with dependency edges involving schemas selected for explicit population, and whenever the graph traversal comes across a dependency reference to a schema we don’t yet know about a thunk is hit that pulls in the dependency information for that schema from the database. We continue passing more dependent objects back and forth between the source and target until no more dependency references are found. This gives us the list of all the extra objects to populate in the source and target, and object population can then proceed. 4. Object blacklists and fast dependencies When we tested this solution, we were puzzled in that in some of our databases most of the system schemas (WMSYS, ORDSYS, EXFSYS, XDB, etc) were being pulled in, and this was increasing the database registration and comparison time quite significantly. After debugging, we discovered that the culprits were database tables that used one of the Oracle PL/SQL types (eg the SDO_GEOMETRY spatial type). These were creating a dependency chain from the database tables we were populating to the system schemas, and hence pulling in most of the system objects in that schema. To solve this we introduced blacklists of objects we wouldn’t follow any dependency chain through. As well as the Oracle-supplied PL/SQL types (MDSYS.SDO_GEOMETRY, ORDSYS.SI_COLOR, among others) we also decided to blacklist the entire PUBLIC and SYS schemas, as any references to those would likely lead to a blow up in the dependency graph that would massively increase the database registration time, and could result in the client running out of memory. Even with these improvements, each dependency query was taking upwards of a minute. We discovered from Oracle execution plans that there were some columns, with dependency information we required, that were querying system tables with no indexes on them! To cut a long story short, running the following query: SELECT * FROM all_tab_cols WHERE data_type_owner = ‘XDB’; results in a full table scan of the SYS.COL$ system table! This single clause was responsible for over half the execution time of the dependency query. Hence, the ‘Ignore slow dependencies’ option was born – not querying this and a couple of similar clauses to drastically speed up the dependency query execution time, at the expense of producing incorrect sync scripts in rare edge cases. Needless to say, along with the sync script action ordering, the dependency code in the database registration is one of the most complicated and most rewritten parts of the Schema Compare for Oracle engine. The beta of Schema Compare for Oracle is out now; if you find a bug in it, please do tell us so we can get it fixed!

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• Loading any MVC page fails with the error "An item with the same key has already been added."

  - by MajorRefactoring

  I am having an intermittent issue that is appearing on one server only, and is causing all MVC pages to fail to load with the error "An item with the same key has already been added." Restarting the application pool fixes the issue, but until then, loading any mvc page throws the following exception: Event code: 3005 Event message: An unhandled exception has occurred. Event time: 10/11/2012 08:09:24 Event time (UTC): 10/11/2012 08:09:24 Event ID: d76264aedc4241d4bce9247692510466 Event sequence: 6407 Event occurrence: 30 Event detail code: 0 Application information: Application domain: /LM/W3SVC/21/ROOT-2-129969647741292058 Trust level: Full Application Virtual Path: / Application Path: d:\websites\SiteAndAppPoolName\ Machine name: UKSERVER Process information: Process ID: 6156 Process name: w3wp.exe Account name: IIS APPPOOL\SiteAndAppPoolName Exception information: Exception type: ArgumentException Exception message: An item with the same key has already been added. Server stack trace: at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer) at System.Web.WebPages.Scope.WebConfigScopeDictionary.<>c__DisplayClass4.<.ctor>b__0() at System.Lazy`1.CreateValue() Exception rethrown at [0]: at System.Lazy`1.get_Value() at System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value) at System.Web.Mvc.ViewContext.ScopeGet[TValue](IDictionary`2 scope, String name, TValue defaultValue) at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.ViewContext.GetClientValidationEnabled(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.Html.FormExtensions.FormHelper(HtmlHelper htmlHelper, String formAction, FormMethod method, IDictionary`2 htmlAttributes) at System.Web.Mvc.Html.FormExtensions.BeginForm(HtmlHelper htmlHelper, String actionName, String controllerName) at ASP._Page_Views_Dashboard_Functions_BookingQuickLookup_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions\BookingQuickLookup.cshtml:line 3 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData) at ASP._Page_Views_Dashboard_Functions_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions.cshtml:line 5 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.RenderPartialExtensions.RenderPartial(HtmlHelper htmlHelper, String partialViewName, Object model) at ASP._Page_Views_Dashboard_Index_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Index.cshtml:line 9 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) at System.Web.Mvc.MvcHandler.<>c__DisplayClass6.<>c__DisplayClassb.<BeginProcessRequest>b__5() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() at System.Web.Mvc.MvcHandler.<>c__DisplayClasse.<EndProcessRequest>b__d() at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Request information: Request URL: http://SiteAndAppPoolName.spawtz.com/Dashboard Request path: /Dashboard User host address: 86.164.135.41 User: Is authenticated: False Authentication Type: Thread account name: IIS APPPOOL\SiteAndAppPoolName Thread information: Thread ID: 17 Thread account name: IIS APPPOOL\SiteAndAppPoolName Is impersonating: False Stack trace: at System.Lazy`1.get_Value() at System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value) at System.Web.Mvc.ViewContext.ScopeGet[TValue](IDictionary`2 scope, String name, TValue defaultValue) at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.ViewContext.GetClientValidationEnabled(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.Html.FormExtensions.FormHelper(HtmlHelper htmlHelper, String formAction, FormMethod method, IDictionary`2 htmlAttributes) at System.Web.Mvc.Html.FormExtensions.BeginForm(HtmlHelper htmlHelper, String actionName, String controllerName) at ASP._Page_Views_Dashboard_Functions_BookingQuickLookup_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions\BookingQuickLookup.cshtml:line 3 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData) at ASP._Page_Views_Dashboard_Functions_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions.cshtml:line 5 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.RenderPartialExtensions.RenderPartial(HtmlHelper htmlHelper, String partialViewName, Object model) at ASP._Page_Views_Dashboard_Index_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Index.cshtml:line 9 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) at System.Web.Mvc.MvcHandler.<>c__DisplayClass6.<>c__DisplayClassb.<BeginProcessRequest>b__5() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() at System.Web.Mvc.MvcHandler.<>c__DisplayClasse.<EndProcessRequest>b__d() at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Custom event details: As mentioned, it's every MVC action that throws this error until the app pool is restarted, and the error seems to be occurring in System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value) Has anyone seen this issue before? It's only happening on this server, on any of the app pools on the server (not confined to this one) and an app pool restart sorts it. Any help much appreciated. Cheers, Matthew

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• xsd validation againts xsd generated class level validation

  - by Miral

  In my project I have very big XSD file which i use to validate some XML request and response to a 3rd party. For the above scenario I can have 2 approaches 1) Create XML and then validate against give XSD 2) Create classes from XSD with the help of XSD gen tool, add xtra bit of attirbutes and use them for validation. Validation in the second way will work somewhat in this manner, a) convert xml request/response into object with XML Serialization b) validate the object with custom attributes set on each property, i.e. Pass the object to a method which will validate the object by iterating through properties and its custom attributes set on the each property, and this will return a boolean value if the object validates and that determines whether the xml request is valid or not? Now the concern which approach is good in terms of performance and anything else???

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• SelectionChanged event binding in Silverlight+MVVM-Light

  - by Budda

  The handler of the "SelectionChanged" event of the ComboBox control has the following signature: void SelectionChangedMethod(object sender, SelectionChangedEventArgs e) How to bind to that property under Silverlight 4 and MVVM-Light to the corresponding method of the ViewModel object? As far as I know, I need to do something like this: public void Changed(Object obj, SelectionChangedEventArgs e) { // .... implement logic here } RelayCommand<Object, SelectionChangedEventArgs> _command; public ICommand ObjectSelectionChanged { get { if (_command == null) { _command = new RelayCommand<Object, SelectionChangedEventArgs>(Changed); } return _command; } } The problem is that RelayCommand class in the MVVM-Light framework doesn't support 2 generic parameters... Is there any solution or workaround for this case? How bind control event to the method with 2 parameters?

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• Usabe of Python 3 super()

  - by deamon

  I wonder when to use what flavour of Python 3 super(). Help on class super in module builtins: class super(object) | super() -> same as super(__class__, <first argument>) | super(type) -> unbound super object | super(type, obj) -> bound super object; requires isinstance(obj, type) | super(type, type2) -> bound super object; requires issubclass(type2, type) Until now I've used super() only without arguments and it worked as expected (by a Java developer). Questions: What does "bound" mean in this context? What is the difference between bound and unbound super object? When to use super(type, obj) and when super(type, type2)? Would it be better to name the super class like in Mother.__init__(...)?

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