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• My linux server takes more than an hour to boot. Suggestions?

  - by jamieb

  I am building a CentOS 5.4 system that boots off a compact flash card using a card reader that emulates an IDE drive. It literally takes about an hour to boot. The ultra-slow part occurs when Grub is loading the kernel. Once that's done, the rest of the boot process only takes about a minute to get to a login prompt. Does anyone have any suggestions? I suspect that it may have to do with UDMA. Everything IDE-related in my BIOS seems to checkout. The read performance hdparm is telling me 1.77 MB/s. Ouch! (But even at that rate, it still shouldn't take an hour to decompress and load the kernel) [root@server ~]# hdparm -tT /dev/hdc /dev/hdc: Timing cached reads: 2444 MB in 2.00 seconds = 1222.04 MB/sec Timing buffered disk reads: 6 MB in 3.39 seconds = 1.77 MB/sec Trying to enable DMA is a no-go though: [root@server ~]# hdparm -d1 /dev/hdc /dev/hdc: setting using_dma to 1 (on) HDIO_SET_DMA failed: Operation not permitted using_dma = 0 (off) Here's some command outputs that might help: System [root@server ~]# uname -a Linux server.localdomain 2.6.18-164.el5xen #1 SMP Thu Sep 3 04:47:32 EDT 2009 i686 i686 i386 GNU/Linux PCI info: [root@server ~]# lspci -v 00:00.0 Host bridge: Intel Corporation 82945G/GZ/P/PL Memory Controller Hub (rev 02) Subsystem: Intel Corporation 82945G/GZ/P/PL Memory Controller Hub Flags: bus master, fast devsel, latency 0 Capabilities: [e0] Vendor Specific Information 00:02.0 VGA compatible controller: Intel Corporation 82945G/GZ Integrated Graphics Controller (rev 02) (prog-if 00 [VGA controller]) Subsystem: Intel Corporation 82945G/GZ Integrated Graphics Controller Flags: bus master, fast devsel, latency 0, IRQ 10 Memory at fdf00000 (32-bit, non-prefetchable) [size=512K] I/O ports at ff00 [size=8] Memory at d0000000 (32-bit, prefetchable) [size=256M] Memory at fdf80000 (32-bit, non-prefetchable) [size=256K] Capabilities: [90] Message Signalled Interrupts: 64bit- Queue=0/0 Enable- Capabilities: [d0] Power Management version 2 00:1d.0 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #1 (rev 01) (prog-if 00 [UHCI]) Subsystem: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #1 Flags: bus master, medium devsel, latency 0, IRQ 16 I/O ports at fe00 [size=32] 00:1d.1 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #2 (rev 01) (prog-if 00 [UHCI]) Subsystem: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #2 Flags: bus master, medium devsel, latency 0, IRQ 17 I/O ports at fd00 [size=32] 00:1d.2 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #3 (rev 01) (prog-if 00 [UHCI]) Subsystem: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #3 Flags: bus master, medium devsel, latency 0, IRQ 18 I/O ports at fc00 [size=32] 00:1d.3 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #4 (rev 01) (prog-if 00 [UHCI]) Subsystem: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #4 Flags: bus master, medium devsel, latency 0, IRQ 19 I/O ports at fb00 [size=32] 00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2 EHCI Controller (rev 01) (prog-if 20 [EHCI]) Subsystem: Intel Corporation 82801G (ICH7 Family) USB2 EHCI Controller Flags: bus master, medium devsel, latency 0, IRQ 16 Memory at fdfff000 (32-bit, non-prefetchable) [size=1K] Capabilities: [50] Power Management version 2 Capabilities: [58] Debug port 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev e1) (prog-if 01 [Subtractive decode]) Flags: bus master, fast devsel, latency 0 Bus: primary=00, secondary=01, subordinate=01, sec-latency=32 I/O behind bridge: 0000d000-0000dfff Memory behind bridge: fde00000-fdefffff Prefetchable memory behind bridge: 00000000fdd00000-00000000fdd00000 Capabilities: [50] #0d [0000] 00:1f.0 ISA bridge: Intel Corporation 82801GB/GR (ICH7 Family) LPC Interface Bridge (rev 01) Subsystem: Intel Corporation 82801GB/GR (ICH7 Family) LPC Interface Bridge Flags: bus master, medium devsel, latency 0 Capabilities: [e0] Vendor Specific Information 00:1f.2 IDE interface: Intel Corporation 82801GB/GR/GH (ICH7 Family) SATA IDE Controller (rev 01) (prog-if 80 [Master]) Subsystem: Intel Corporation 82801GB/GR/GH (ICH7 Family) SATA IDE Controller Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 17 I/O ports at <unassigned> I/O ports at <unassigned> I/O ports at <unassigned> I/O ports at <unassigned> I/O ports at f800 [size=16] Capabilities: [70] Power Management version 2 00:1f.3 SMBus: Intel Corporation 82801G (ICH7 Family) SMBus Controller (rev 01) Subsystem: Intel Corporation 82801G (ICH7 Family) SMBus Controller Flags: medium devsel, IRQ 17 I/O ports at 0500 [size=32] 01:04.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10) Subsystem: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ Flags: bus master, medium devsel, latency 32, IRQ 18 I/O ports at de00 [size=256] Memory at fdeff000 (32-bit, non-prefetchable) [size=256] Capabilities: [50] Power Management version 2 01:06.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10) Subsystem: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ Flags: bus master, medium devsel, latency 32, IRQ 17 I/O ports at dc00 [size=256] Memory at fdefe000 (32-bit, non-prefetchable) [size=256] Capabilities: [50] Power Management version 2 01:07.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10) Subsystem: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ Flags: bus master, medium devsel, latency 32, IRQ 19 I/O ports at da00 [size=256] Memory at fdefd000 (32-bit, non-prefetchable) [size=256] Capabilities: [50] Power Management version 2 hdparm ouput: [root@server ~]# hdparm /dev/hdc /dev/hdc: multcount = 0 (off) IO_support = 0 (default 16-bit) unmaskirq = 0 (off) using_dma = 0 (off) keepsettings = 0 (off) readonly = 0 (off) readahead = 256 (on) geometry = 8146/16/63, sectors = 8211168, start = 0 [root@server ~]# hdparm -I /dev/hdc /dev/hdc: ATA device, with non-removable media Model Number: InnoDisk Corp. - iCF4000 4GB Serial Number: 20091023AACA70000753 Firmware Revision: 081107 Standards: Supported: 5 Likely used: 6 Configuration: Logical max current cylinders 8146 8146 heads 16 16 sectors/track 63 63 -- CHS current addressable sectors: 8211168 LBA user addressable sectors: 8211168 device size with M = 1024*1024: 4009 MBytes device size with M = 1000*1000: 4204 MBytes (4 GB) Capabilities: LBA, IORDY(can be disabled) Standby timer values: spec'd by Vendor R/W multiple sector transfer: Max = 2 Current = 2 DMA: mdma0 mdma1 mdma2 udma0 udma1 *udma2 udma3 udma4 Cycle time: min=120ns recommended=120ns PIO: pio0 pio1 pio2 pio3 pio4 Cycle time: no flow control=120ns IORDY flow control=120ns Commands/features: Enabled Supported: * Power Management feature set * WRITE_BUFFER command * READ_BUFFER command * NOP cmd * CFA feature set * Mandatory FLUSH_CACHE HW reset results: CBLID- above Vih Device num = 0 CFA power mode 1: enabled and required by some commands Maximum current = 100ma Checksum: correct

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• Connecting a LAN to an OpenVPN server via a windows 7 client gateway

  - by user705142

  I've got OpenVPN set up between my windows 7 client and linux server. The goal is that I'll get secure access to a webapp running on the server from any computer on the client LAN. I'm using ccd to assign static ip addresses to each client connection, with key authentication. It's working on my client machine (10.83.41.9), and when you go to the gateway IP address (10.83.41.1), it loads up the webapp. Now I really need the other computers on the client LAN to be able to connect to the webapp as well, via the windows machine. The client has a static IP address of 192.168.2.100 on the LAN, and I've enabled IP forwarding in windows (confirmed by ipconfig /all). In my router I've forwarded 10.83.41.1 / 255.255.255.255 to 192.168.2.100. In server.conf I have.. route 192.168.2.0 255.255.255.0 And in the office ccd.. ifconfig-push 10.83.41.9 10.83.41.10 iroute 192.168.2.0 255.255.255.0 The client log is as follows: Thu Mar 15 20:19:56 2012 OpenVPN 2.2.2 Win32-MSVC++ [SSL] [LZO2] [PKCS11] built on Dec 15 2011 Thu Mar 15 20:19:56 2012 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables Thu Mar 15 20:19:56 2012 Control Channel Authentication: using 'ta.key' as a OpenVPN static key file Thu Mar 15 20:19:56 2012 Outgoing Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication Thu Mar 15 20:19:56 2012 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication Thu Mar 15 20:19:56 2012 LZO compression initialized Thu Mar 15 20:19:56 2012 Control Channel MTU parms [ L:1558 D:166 EF:66 EB:0 ET:0 EL:0 ] Thu Mar 15 20:19:56 2012 Socket Buffers: R=[8192->8192] S=[64512->64512] Thu Mar 15 20:19:56 2012 Data Channel MTU parms [ L:1558 D:1450 EF:58 EB:135 ET:0 EL:0 AF:3/1 ] Thu Mar 15 20:19:56 2012 Local Options hash (VER=V4): '9e7066d2' Thu Mar 15 20:19:56 2012 Expected Remote Options hash (VER=V4): '162b04de' Thu Mar 15 20:19:56 2012 UDPv4 link local: [undef] Thu Mar 15 20:19:56 2012 UDPv4 link remote: 111.65.224.202:1194 Thu Mar 15 20:19:56 2012 TLS: Initial packet from 111.65.224.202:1194, sid=ceb04c22 8cc6d151 Thu Mar 15 20:19:56 2012 VERIFY OK: depth=1, /C=NZ/O=XXX./CN=XXX Thu Mar 15 20:19:56 2012 VERIFY OK: nsCertType=SERVER Thu Mar 15 20:19:56 2012 VERIFY OK: depth=0, /C=NZ/O=XXX./CN=XXX Thu Mar 15 20:19:56 2012 Replay-window backtrack occurred [1] Thu Mar 15 20:19:56 2012 Data Channel Encrypt: Cipher 'AES-256-CBC' initialized with 256 bit key Thu Mar 15 20:19:56 2012 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Thu Mar 15 20:19:56 2012 Data Channel Decrypt: Cipher 'AES-256-CBC' initialized with 256 bit key Thu Mar 15 20:19:56 2012 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Thu Mar 15 20:19:56 2012 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA Thu Mar 15 20:19:56 2012 [server] Peer Connection Initiated with 111.65.224.202:1194 Thu Mar 15 20:19:58 2012 SENT CONTROL [server]: 'PUSH_REQUEST' (status=1) Thu Mar 15 20:19:59 2012 PUSH: Received control message: 'PUSH_REPLY,route 10.83.41.1,topology net30,ping 10,ping-restart 120,ifconfig 10.83.41.9 10.83.41.10' Thu Mar 15 20:19:59 2012 OPTIONS IMPORT: timers and/or timeouts modified Thu Mar 15 20:19:59 2012 OPTIONS IMPORT: --ifconfig/up options modified Thu Mar 15 20:19:59 2012 OPTIONS IMPORT: route options modified Thu Mar 15 20:19:59 2012 ROUTE default_gateway=192.168.2.1 Thu Mar 15 20:19:59 2012 TAP-WIN32 device [OpenVPN] opened: \\.\Global\{B32D85C9-1942-42E2-80BA-7E0B5BB5185F}.tap Thu Mar 15 20:19:59 2012 TAP-Win32 Driver Version 9.9 Thu Mar 15 20:19:59 2012 TAP-Win32 MTU=1500 Thu Mar 15 20:19:59 2012 Notified TAP-Win32 driver to set a DHCP IP/netmask of 10.83.41.9/255.255.255.252 on interface {B32D85C9-1942-42E2-80BA-7E0B5BB5185F} [DHCP-serv: 10.83.41.10, lease-time: 31536000] Thu Mar 15 20:19:59 2012 Successful ARP Flush on interface [45] {B32D85C9-1942-42E2-80BA-7E0B5BB5185F} Thu Mar 15 20:20:04 2012 TEST ROUTES: 1/1 succeeded len=1 ret=1 a=0 u/d=up Thu Mar 15 20:20:04 2012 C:\WINDOWS\system32\route.exe ADD 10.83.41.1 MASK 255.255.255.255 10.83.41.10 Thu Mar 15 20:20:04 2012 ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=30 and dwForwardType=4 Thu Mar 15 20:20:04 2012 Route addition via IPAPI succeeded [adaptive] Thu Mar 15 20:20:04 2012 Initialization Sequence Completed From the other machines I can ping 192.169.2.100, but not 10.83.41.1. In the how-to, it mentions "Make sure your network interface is in promiscuous mode." as well. I can't find in the windows network config, so this may or may not be part of it. Ideally this would be achieved without any special configuration the other LAN computers. Not sure how far I'm going to get on my own at this point, any ideas? Is there something I'm missing, or anything I should need to know?

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• OpenVPN IPv6 over IPv4 tunnel

  - by user66779

  Today I installed OpenVPN 2.3rc2 on both my windows 7 client machine and centos 6 server. This new version of OpenVPN provides full compatibility for IPv6. The Problem: I am currently able to connect to the server (through the IPv4 tunnel) and ping the IPv6 address which is assigned to my client and I can also ping the tun0 interface on the server. However, I cannot browse to any IPv6 websites. My vps provider has given me this: 2607:f840:0044:0022:0000:0000:0000:0000/64 is routed to this server (2607:f840:0:3f:0:0:0:eda). This is ifconfig after setup with OpenVPN running: eth0 Link encap:Ethernet HWaddr 00:16:3E:12:77:54 inet addr:208.111.39.160 Bcast:208.111.39.255 Mask:255.255.255.0 inet6 addr: 2607:f740:0:3f::eda/64 Scope:Global inet6 addr: fe80::216:3eff:fe12:7754/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2317253 errors:0 dropped:7263 overruns:0 frame:0 TX packets:1977414 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1696120096 (1.5 GiB) TX bytes:1735352992 (1.6 GiB) Interrupt:29 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.8.0.1 P-t-P:10.8.0.2 Mask:255.255.255.255 inet6 addr: 2607:f740:44:22::1/64 Scope:Global UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:739567 errors:0 dropped:0 overruns:0 frame:0 TX packets:1218240 errors:0 dropped:1542 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:46512557 (44.3 MiB) TX bytes:1559930874 (1.4 GiB) So OpenVPN is sucessfully creating a tun0 interface and assigning clients IPv6 addresses using 2607:f840:44:22::/64. The first client to connect is getting 2607:f840:44:22::1000 and the second 2607:f840:44:22::1001, and so on... plus 1 each time. After connecting as the first client, I can ping from my windows client machine 2607:f740:44:22::1 and 2607:f740:44:22::1000. However, I have no access to IPv6 websites. I believe the problem is that the tun0 IPv6 addressees are not being forwarded to the eth0 interface. This is the firewall running on the server: #!/bin/sh # # iptables configuration script # # Flush all current rules from iptables # iptables -F iptables -t nat -F # # Allow SSH connections on tcp port 22 # iptables -A INPUT -i eth0 -p tcp --dport 22 -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 22 -j ACCEPT # # Set access for localhost # iptables -A INPUT -i lo -j ACCEPT # # Accept connections on 1195 for vpn access from client # iptables -A INPUT -i eth0 -p udp --dport 1195 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p udp --sport 1195 -m state --state ESTABLISHED -j ACCEPT # # Apply forwarding for OpenVPN Tunneling # iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to 209.111.39.160 iptables -A FORWARD -j REJECT # # Enable forwarding # echo 1 > /proc/sys/net/ipv4/ip_forward # # Set default policies for INPUT, FORWARD and OUTPUT chains # iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT # # IPv6 # IP6TABLES=/sbin/ip6tables $IP6TABLES -F INPUT $IP6TABLES -F FORWARD $IP6TABLES -F OUTPUT echo -n "1" >/proc/sys/net/ipv6/conf/all/forwarding echo -n "1" >/proc/sys/net/ipv6/conf/all/proxy_ndp echo -n "0" >/proc/sys/net/ipv6/conf/all/autoconf echo -n "0" >/proc/sys/net/ipv6/conf/all/accept_ra $IP6TABLES -A INPUT -i eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT $IP6TABLES -A INPUT -i eth0 -p tcp --dport 22 -j ACCEPT $IP6TABLES -A INPUT -i eth0 -p icmpv6 -j ACCEPT $IP6TABLES -P INPUT ACCEPT $IP6TABLES -P FORWARD ACCEPT $IP6TABLES -P OUTPUT ACCEPT Server.conf: server-ipv6 2607:f840:44:22::/64 server 10.8.0.0 255.255.255.0 port 1195 proto udp dev tun ca ca.crt cert server.crt key server.key dh dh2048.pem ifconfig-pool-persist ipp.txt push "redirect-gateway def1 bypass-dhcp" push "dhcp-option DNS 208.67.222.222" push "dhcp-option DNS 208.67.220.220" keepalive 10 60 tls-auth ta.key 0 cipher AES-256-CBC comp-lzo user nobody group nobody persist-key persist-tun status openvpn-status.log log-append openvpn.log verb 5 Client.conf: client dev tun nobind keepalive 10 60 hand-window 15 remote 209.111.39.160 1195 udp persist-key persist-tun ca ca.crt key client1.key cert client1.crt remote-cert-tls server tls-auth ta.key 1 comp-lzo verb 3 cipher AES-256-CBC I'm not sure where I am going wrong, it could be the firewall, or something missing from server or client.conf. This version of OpenVPN was only released yesterday, and there's little info on the internet about how to setup an IPv6 over IPv4 vpn tunnel. I've read the manual for this new version of OpenVPN (parts pertaining to IPv6) and it provides very little info too. Thanks for any help.

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• Multiple Graphics Cards on Fedora 15 (Gnome 3)

  - by Michael

  I have the (delightful) misfortune of having 3 graphics cards. They are XFX Radeon 5750s. Each drives 2 monitors via dvi. I am having a really hard time getting these running on fedora 15 (gnome 3). So my setup is 3 columns of 2 monitors (the upper monitor is mounted upside down in each column to reduce the bezel between monitors). When the (graphical) login screen comes up all 6 have the blue stripey background that must be the default, but then when I login, things get interesting. In the xorg.conf below, you will see only 2 of the screens in the serverlayout while the other 4 are commented out. Logging in with only 2 of the screens active works well (and it even remembers that the top one is upside down, and should be considered above the lower, i am not sure where it stores this info, but i set it using the graphical "Displays" settings) However, as soon as I uncomment a third screen, or more, it gives me an error message when I login. It's one of those friendly, less helpful messages (Oh no! Something has gone wrong. A problem has occurred and the system can't recover. Please log out and try again). If i do not use an xorg.conf, then the "Displays" prefs pane shows only the two monitors on one of my graphics cards Thanks to anyone who can help me get going! (xorg.conf and then lspci below, and xorg log) xorg.conf Section "ServerLayout" Identifier "X.org Configured" Screen "Screen0" 0 0 Screen "Screen1" Below "Screen0" # Screen "Screen2" RightOf "Screen0" # Screen "Screen3" RightOf "Screen1" # Screen "Screen4" RightOf "Screen3" # Screen "Screen5" RightOf "Screen4" InputDevice "Mouse0" "CorePointer" InputDevice "Keyboard0" "CoreKeyboard" EndSection Section "Files" ModulePath "/usr/lib/xorg/modules" FontPath "catalogue:/etc/X11/fontpath.d" FontPath "built-ins" EndSection Section "Module" Load "record" Load "dri" Load "dbe" Load "extmod" Load "dri2" Load "glx" EndSection Section "InputDevice" Identifier "Keyboard0" Driver "kbd" EndSection Section "InputDevice" Identifier "Mouse0" Driver "mouse" Option "Protocol" "auto" Option "Device" "/dev/input/mice" Option "ZAxisMapping" "4 5 6 7" EndSection Section "Monitor" Identifier "Monitor0" VendorName "Monitor Vendor" ModelName "Monitor Model" EndSection Section "Monitor" Identifier "Monitor1" VendorName "Monitor Vendor" ModelName "Monitor Model" EndSection Section "Monitor" Identifier "Monitor2" VendorName "Monitor Vendor" ModelName "Monitor Model" EndSection Section "Monitor" Identifier "Monitor3" VendorName "Monitor Vendor" ModelName "Monitor Model" EndSection Section "Monitor" Identifier "Monitor4" VendorName "Monitor Vendor" ModelName "Monitor Model" EndSection Section "Monitor" Identifier "Monitor5" VendorName "Monitor Vendor" ModelName "Monitor Model" EndSection Section "Device" Identifier "Card0" Driver "radeon" BusID "PCI:4:0:0" EndSection Section "Device" Identifier "Card1" Driver "radeon" BusID "PCI:5:0:0" EndSection Section "Device" Identifier "Card2" Driver "radeon" BusID "PCI:6:0:0" EndSection Section "Screen" Identifier "Screen0" Device "Card0" Monitor "Monitor0" SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Screen" Identifier "Screen1" Device "Card0" Monitor "Monitor1" SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Screen" Identifier "Screen2" Device "Card1" Monitor "Monitor2" SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Screen" Identifier "Screen3" Device "Card1" Monitor "Monitor3" SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Screen" Identifier "Screen4" Device "Card2" Monitor "Monitor4" SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Screen" Identifier "Screen5" Device "Card2" Monitor "Monitor5" SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection lspci output follows [tgm@tgm ~]$ lspci 00:00.0 Host bridge: Intel Corporation 5520/5500/X58 I/O Hub to ESI Port (rev 13) 00:01.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 1 (rev 13) 00:03.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 3 (rev 13) 00:07.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 7 (rev 13) 00:14.0 PIC: Intel Corporation 5520/5500/X58 I/O Hub System Management Registers (rev 13) 00:14.1 PIC: Intel Corporation 5520/5500/X58 I/O Hub GPIO and Scratch Pad Registers (rev 13) 00:14.2 PIC: Intel Corporation 5520/5500/X58 I/O Hub Control Status and RAS Registers (rev 13) 00:14.3 PIC: Intel Corporation 5520/5500/X58 I/O Hub Throttle Registers (rev 13) 00:1a.0 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #4 00:1a.1 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #5 00:1a.2 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #6 00:1a.7 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #2 00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller 00:1c.0 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 1 00:1c.1 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Port 2 00:1c.2 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 3 00:1d.0 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #1 00:1d.1 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #2 00:1d.2 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #3 00:1d.7 USB Controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #1 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 90) 00:1f.0 ISA bridge: Intel Corporation 82801JIR (ICH10R) LPC Interface Controller 00:1f.2 IDE interface: Intel Corporation 82801JI (ICH10 Family) 4 port SATA IDE Controller #1 00:1f.3 SMBus: Intel Corporation 82801JI (ICH10 Family) SMBus Controller 00:1f.5 IDE interface: Intel Corporation 82801JI (ICH10 Family) 2 port SATA IDE Controller #2 02:00.0 PCI bridge: nVidia Corporation NF200 PCIe 2.0 switch for mainboards (rev a3) 03:00.0 PCI bridge: nVidia Corporation NF200 PCIe 2.0 switch for mainboards (rev a3) 03:02.0 PCI bridge: nVidia Corporation NF200 PCIe 2.0 switch for mainboards (rev a3) 04:00.0 VGA compatible controller: ATI Technologies Inc Juniper [Radeon HD 5750 Series] 04:00.1 Audio device: ATI Technologies Inc Juniper HDMI Audio [Radeon HD 5700 Series] 05:00.0 VGA compatible controller: ATI Technologies Inc Juniper [Radeon HD 5750 Series] 05:00.1 Audio device: ATI Technologies Inc Juniper HDMI Audio [Radeon HD 5700 Series] 06:00.0 VGA compatible controller: ATI Technologies Inc Juniper [Radeon HD 5750 Series] 06:00.1 Audio device: ATI Technologies Inc Juniper HDMI Audio [Radeon HD 5700 Series] 07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02) 08:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02) xorg log (posted to fpaste due to how long it is. thanks to marcusw for the request) http://www.fpaste.org/r5ww/ xorg log with all 6 monitors enabled in xorg.conf (they all turn on and have blue, but then one gets the aforementioned user-friendly error message). http://www.fpaste.org/X63H/

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• Combined SOAP/JSON/XML in WCF, using UriTemplate

  - by gregmac

  I'm trying to build a generic web service interface using WCF, to allow 3rd party developers to hook into our software. After much struggling and reading (this question helped a lot), I finally got SOAP, JSON and XML (POX) working together. To simplify, here's my code (to make this example simple, I'm not using interfaces -- I did try this both ways): <ServiceContract()> _ Public Class TestService Public Sub New() End Sub <OperationContract()> _ <WebGet()> _ Public Function GetDate() As DateTime Return Now End Function '<WebGet(UriTemplate:="getdateoffset/{numDays}")> _ <OperationContract()> _ Public Function GetDateOffset(ByVal numDays As Integer) As DateTime Return Now.AddDays(numDays) End Function End Class and the web.config code: <services> <service name="TestService" behaviorConfiguration="TestServiceBehavior"> <endpoint address="soap" binding="basicHttpBinding" contract="TestService"/> <endpoint address="json" binding="webHttpBinding" behaviorConfiguration="jsonBehavior" contract="TestService"/> <endpoint address="xml" binding="webHttpBinding" behaviorConfiguration="poxBehavior" contract="TestService"/> <endpoint address="mex" contract="IMetadataExchange" binding="mexHttpBinding" /> </service> </services> <behaviors> <endpointBehaviors> <behavior name="jsonBehavior"> <enableWebScript/> </behavior> <behavior name="poxBehavior"> <webHttp /> </behavior> </endpointBehaviors> <serviceBehaviors> <behavior name="TestServiceBehavior"> <serviceMetadata httpGetEnabled="true"/> <serviceDebug includeExceptionDetailInFaults="false"/> </behavior> </serviceBehaviors> </behaviors> This actually works -- I'm able to go to TestService.svc/xml/GetDate for xml, TestService.svc/json/GetDate for json, and point a SOAP client at TestService.svc?wsdl and have the SOAP queries work. The part I'd like to fix is the queries. I have to use TestService.svc/xml/GetDateOffset?numDays=4 instead of TestService.svc/xml/GetDateOffset/4. If I specify the UriTemplate, I get the error: Endpoints using 'UriTemplate' cannot be used with 'System.ServiceModel.Description.WebScriptEnablingBehavior'. But of course without using <enableWebScript/>, JSON doesn't work. The only other thing I've seen that I think will work is making 3 different services (.svc files), that all implement an interface that specifies the contract, but in the classes specify different WebGet/WebInvoke attributes on each class. This seems like a lot of extra work, that frankly, I don't see why the framework doesn't handle for me. The implementation of the classes would all be the same, except for the attributes, which means over time it would be easy for bugs/changes to get fixed/done in one implementation but not the others, leading to inconsistent behaviour when using the JSON vs SOAP implementation for example. Am I doing something wrong here? Am I taking a totally wrong approach and misusing WCF? Is there a better way to do this? With my experience doing web stuff, I think it should be possible for some kind of framework to handle this ... I even have an idea in my head of how to build it. It just seems like WCF is supposed to be doing this, and I don't really want to reinvent the wheel.

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• Creating a Reverse Proxy using Jpcap

  - by Ramon Marco Navarro

  I need to create a program that receives HTTP request and forwards those requests to the web servers. I have successfully made this using only Java Sockets but the client needed the program to be implemented in Jpcap. I'd like to know if this is possible and what literature I should be reading for this project. This is what I have now by stitching together pieces from the Jpcap tutorial: import java.net.InetAddress; import java.io.*; import jpcap.*; import jpcap.packet.*; public class Router { public static void main(String args[]) { //Obtain the list of network interfaces NetworkInterface[] devices = JpcapCaptor.getDeviceList(); //for each network interface for (int i = 0; i < devices.length; i++) { //print out its name and description System.out.println(i+": "+devices[i].name + "(" + devices[i].description+")"); //print out its datalink name and description System.out.println(" datalink: "+devices[i].datalink_name + "(" + devices[i].datalink_description+")"); //print out its MAC address System.out.print(" MAC address:"); for (byte b : devices[i].mac_address) System.out.print(Integer.toHexString(b&0xff) + ":"); System.out.println(); //print out its IP address, subnet mask and broadcast address for (NetworkInterfaceAddress a : devices[i].addresses) System.out.println(" address:"+a.address + " " + a.subnet + " "+ a.broadcast); } int index = 1; // set index of the interface that you want to open. //Open an interface with openDevice(NetworkInterface intrface, int snaplen, boolean promics, int to_ms) JpcapCaptor captor = null; try { captor = JpcapCaptor.openDevice(devices[index], 65535, false, 20); captor.setFilter("port 80 and host 192.168.56.1", true); } catch(java.io.IOException e) { System.err.println(e); } //call processPacket() to let Jpcap call PacketPrinter.receivePacket() for every packet capture. captor.loopPacket(-1,new PacketPrinter()); captor.close(); } } class PacketPrinter implements PacketReceiver { //this method is called every time Jpcap captures a packet public void receivePacket(Packet p) { JpcapSender sender = null; try { NetworkInterface[] devices = JpcapCaptor.getDeviceList(); sender = JpcapSender.openDevice(devices[1]); } catch(IOException e) { System.err.println(e); } IPPacket packet = (IPPacket)p; try { // IP Address of machine sending HTTP requests (the client) // It's still on the same LAN as the servers for testing purposes. packet.dst_ip = InetAddress.getByName("192.168.56.2"); } catch(java.net.UnknownHostException e) { System.err.println(e); } //create an Ethernet packet (frame) EthernetPacket ether=new EthernetPacket(); //set frame type as IP ether.frametype=EthernetPacket.ETHERTYPE_IP; //set source and destination MAC addresses // MAC Address of machine running reverse proxy server ether.src_mac = new MacAddress("08:00:27:00:9C:80").getAddress(); // MAC Address of machine running web server ether.dst_mac = new MacAddress("08:00:27:C7:D2:4C").getAddress(); //set the datalink frame of the packet as ether packet.datalink=ether; //send the packet sender.sendPacket(packet); sender.close(); //just print out a captured packet System.out.println(packet); } } Any help would be greatly appreciated. Thank you.

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• NHibernate which cache to use for WinForms application

  - by chiccodoro

  I have a C# WinForms application with a database backend (oracle) and use NHibernate for O/R mapping. I would like to reduce communication to the database as much as possible since the network in here is quite slow, so I read about second level caching. I found this quite good introduction, which lists the following available cache implementations. I'm wondering which implementation I should use for my application. The caching should be simple, it should not significantly slow down the first occurrence of a query, and it should not take much memory to load the implementing assemblies. (With NHibernate and Castle, the application already takes up to 80 MB of RAM!) Velocity: uses Microsoft Velocity which is a highly scalable in-memory application cache for all kinds of data. Prevalence: uses Bamboo.Prevalence as the cache provider. Bamboo.Prevalence is a .NET implementation of the object prevalence concept brought to life by Klaus Wuestefeld in Prevayler. Bamboo.Prevalence provides transparent object persistence to deterministic systems targeting the CLR. It offers persistent caching for smart client applications. SysCache: Uses System.Web.Caching.Cache as the cache provider. This means that you can rely on ASP.NET caching feature to understand how it works. SysCache2: Similar to NHibernate.Caches.SysCache, uses ASP.NET cache. This provider also supports SQL dependency-based expiration, meaning that it is possible to configure certain cache regions to automatically expire when the relevant data in the database changes. MemCache: uses memcached; memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load. Basically a distributed hash table. SharedCache: high-performance, distributed and replicated memory object caching system. See here and here for more info My considerations so far were: Velocity seems quite heavyweight and overkill (the files totally take 467 KB of disk space, haven't measured the RAM it takes so far because I didn't manage to make it run, see below) Prevalence, at least in my first attempt, slowed down my query from ~0.5 secs to ~5 secs, and caching didn't work (see below) SysCache seems to be for ASP.NET, not for winforms. MemCache and SharedCache seem to be for distributed scenarios. Which one would you suggest me to use? There would also be a built-in implementation, which of course is very lightweight, but the referenced article tells me that I "(...) should never use this cache provider for production code but only for testing." Besides the question which fits best into my situation I also faced problems with applying them: Velocity complained that "dcacheClient" tag not specified in the application configuration file. Specify valid tag in configuration file," although I created an app.config file for the assembly and pasted the example from this article. Prevalence, as mentioned above, heavily slowed down my first query, and the next time the exact same query was executed, another select was sent to the database. Maybe I should "externalize" this topic into another post. I will do that if someone tells me it is absolutely unusual that a query is slowed down so much and he needs further details to help me.

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• War wont deploy "Unresolved <ejb-link>" Glassfish 3, Netbeans 7

  - by Ime Imee

  I have enterprise aplication with ejb and war module, and since I created local interface web module wont deploy. It builds fine. EJB project is referenced inside web project. Also when I delete <ejb-local-ref> from web.xml it deploys, but then lookup method fails. Glassfish error: SEVERE: Exception while deploying the app [Projekat-war] : Error: Unresolved <ejb-link>: Projekat-ejb.jar#ZaWebSessionBean Simple interface: @Local public interface ZaWebSessionBeanLocal { String vrati(String str); } @Stateless public class ZaWebSessionBean implements ZaWebSessionBeanLocal { @Override public String vrati(String str) { return "vrati"; } // Add business logic below. (Right-click in editor and choose // "Insert Code > Add Business Method") } And web.xml <ejb-local-ref> <ejb-ref-name>ZaWebSessionBean</ejb-ref-name> <ejb-ref-type>Session</ejb-ref-type> <local>za_web.ZaWebSessionBeanLocal</local> <ejb-link>Projekat-ejb.jar#ZaWebSessionBean</ejb-link> </ejb-local-ref> Lookup method (generated) : public class HeaderBean { ZaWebSessionBeanLocal zaWebSessionBean = lookupZaWebSessionBeanLocal(); private ZaWebSessionBeanLocal lookupZaWebSessionBeanLocal() { try { Context c = new InitialContext(); return (ZaWebSessionBeanLocal) c.lookup("java:global/Projekat/Projekat-ejb/ZaWebSessionBean!za_web.ZaWebSessionBeanLocal"); } catch (NamingException ne) { Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", ne); throw new RuntimeException(ne); } } Full log: SEVERE: Exception while deploying the app [Projekat-war] : Error: Unresolved <ejb-link>: Projekat-ejb.jar#ZaWebSessionBean SEVERE: Unresolved <ejb-link>: Projekat-ejb.jar#ZaWebSessionBean SEVERE: Exception while deploying the app [Projekat-war] SEVERE: Error: Unresolved <ejb-link>: Projekat-ejb.jar#ZaWebSessionBean java.lang.RuntimeException: Error: Unresolved <ejb-link>: Projekat-ejb.jar#ZaWebSessionBean at com.sun.enterprise.deployment.util.EjbBundleValidator.accept(EjbBundleValidator.java:724) at com.sun.enterprise.deployment.WebBundleDescriptor.visit(WebBundleDescriptor.java:2004) at com.sun.enterprise.deployment.Application.visit(Application.java:1777) at com.sun.enterprise.deployment.archivist.ApplicationFactory.openArchive(ApplicationFactory.java:195) at org.glassfish.javaee.core.deployment.DolProvider.load(DolProvider.java:185) at org.glassfish.javaee.core.deployment.DolProvider.load(DolProvider.java:94) at com.sun.enterprise.v3.server.ApplicationLifecycle.loadDeployer(ApplicationLifecycle.java:827) at com.sun.enterprise.v3.server.ApplicationLifecycle.setupContainerInfos(ApplicationLifecycle.java:769) at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:368) at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:240) at org.glassfish.deployment.admin.DeployCommand.execute(DeployCommand.java:389) at com.sun.enterprise.v3.admin.CommandRunnerImpl$1.execute(CommandRunnerImpl.java:348) at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:363) at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1085) at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$1200(CommandRunnerImpl.java:95) at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1291) at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1259) at com.sun.enterprise.v3.admin.AdminAdapter.doCommand(AdminAdapter.java:461) at com.sun.enterprise.v3.admin.AdminAdapter.service(AdminAdapter.java:212) at com.sun.grizzly.tcp.http11.GrizzlyAdapter.service(GrizzlyAdapter.java:179) at com.sun.enterprise.v3.server.HK2Dispatcher.dispath(HK2Dispatcher.java:117) at com.sun.enterprise.v3.services.impl.ContainerMapper$Hk2DispatcherCallable.call(ContainerMapper.java:354) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59) at com.sun.grizzly.ContextTask.run(ContextTask.java:71) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513) at java.lang.Thread.run(Thread.java:619) SEVERE: Exception while deploying the app [Projekat-war] : Error: Unresolved <ejb-link>: Projekat-ejb.jar#ZaWebSessionBean

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• Problem releasing UIImageView after adding to UIScrollView

  - by Josiah Jordan

  I'm having a memory problem related to UIImageView. After adding this view to my UIScrollView, if I try to release the UIImageView the application crashes. According to the stack trace, something is calling [UIImageView stopAnimating] after [UIImageView dealloc] is called. However, if I don't release the view the memory is never freed up, and I've confirmed that there remains an extra retain call on the view after deallocating...which causes my total allocations to climb quickly and eventually crash the app after loading the view multiple times. I'm not sure what I'm doing wrong here though...I don't know what is trying to access the UIImageView after it has been released. I've included the relevant header and implementation code below (I'm using the Three20 framework, if that has anything to do with it...also, AppScrollView is just a UIScrollView that forwards the touchesEnded event to the next responder): Header: @interface PhotoHiResPreviewController : TTViewController <UIScrollViewDelegate> { NSString* imageURL; UIImage* hiResImage; UIImageView* imageView; UIView* mainView; AppScrollView* mainScrollView; } @property (nonatomic, retain) NSString* imageURL; @property (nonatomic, retain) NSString* imageShortURL; @property (nonatomic, retain) UIImage* hiResImage; @property (nonatomic, retain) UIImageView* imageView; - (id)initWithImageURL:(NSString*)imageTTURL; Implementation: @implementation PhotoHiResPreviewController @synthesize imageURL, hiResImage, imageView; - (id)initWithImageURL:(NSString*)imageTTURL { if (self = [super init]) { hiResImage = nil; NSString *documentsDirectory = [NSString stringWithString:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]]; [self setImageURL:[NSString stringWithFormat:@"%@/%@.jpg", documentsDirectory, imageTTURL]]; } return self; } - (void)loadView { [super loadView]; // Initialize the scroll view hiResImage = [UIImage imageWithContentsOfFile:self.imageURL]; CGSize photoSize = [hiResImage size]; mainScrollView = [[AppScrollView alloc] initWithFrame:[UIScreen mainScreen].bounds]; mainScrollView.autoresizingMask = ( UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight); mainScrollView.backgroundColor = [UIColor blackColor]; mainScrollView.contentSize = photoSize; mainScrollView.contentMode = UIViewContentModeScaleAspectFit; mainScrollView.delegate = self; // Create the image view and add it to the scrollview. UIImageView *tempImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, photoSize.width, photoSize.height)]; tempImageView.contentMode = UIViewContentModeCenter; [tempImageView setImage:hiResImage]; self.imageView = tempImageView; [tempImageView release]; [mainScrollView addSubview:imageView]; // Configure zooming. CGSize screenSize = [[UIScreen mainScreen] bounds].size; CGFloat widthRatio = screenSize.width / photoSize.width; CGFloat heightRatio = screenSize.height / photoSize.height; CGFloat initialZoom = (widthRatio > heightRatio) ? heightRatio : widthRatio; mainScrollView.maximumZoomScale = 3.0; mainScrollView.minimumZoomScale = initialZoom; mainScrollView.zoomScale = initialZoom; mainScrollView.bouncesZoom = YES; mainView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds]; mainView.autoresizingMask = ( UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight); mainView.backgroundColor = [UIColor blackColor]; mainView.contentMode = UIViewContentModeScaleAspectFit; [mainView addSubview:mainScrollView]; // Add to view self.view = mainView; [imageView release]; [mainScrollView release]; [mainView release]; } - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return imageView; } - (void)dealloc { mainScrollView.delegate = nil; TT_RELEASE_SAFELY(imageURL); TT_RELEASE_SAFELY(hiResImage); [super dealloc]; } I'm not sure how to get around this. If I remove the call to [imageView release] at the end of the loadView method everything works fine...but I have massive allocations that quickly climb to a breaking point. If I DO release it, however, there's that [UIImageView stopAnimating] call that crashes the application after the view is deallocated. Thanks for any help! I've been banging my head against this one for days. :-P Cheers, Josiah

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• Is it possible to specify a generic constraint for a type parameter to be convertible FROM another t

  - by fostandy

  Suppose I write a library with the following: public class Bar { /* ... */ } public class SomeWeirdClass<T> where T : ??? { public T BarMaker(Bar b) { // ... play with b T t = (T)b return (T) b; } } Later, I expect users to use my library by defining their own types which are convertible to Bar and using the SomeWeirdClass 'factory'. public class Foo { public static explicit operator Foo(Bar f) { return new Bar(); } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } this will compile if i set where T : Foo but the problem is that I don't know about Foo at the library's compile time, and I actually want something more like where T : some class that can be instantiated, given a Bar Is this possible? From my limited knowledge it does not seem to be, but the ingenuity of the .NET framework and its users always surprises me... This may or not be related to the idea of static interface methods - at least, I can see the value in being able to specify the presence of factory methods to create objects (similar to the same way that you can already perform where T : new()) edit: Solution - thanks to Nick and bzIm - For other readers I'll provide a completed solution as I understand it: edit2: This solution requires Foo to expose a public default constructor. For an even stupider better solution that does not require this see the very bottom of this post. public class Bar {} public class SomeWeirdClass<T> where T : IConvertibleFromBar<T>, new() { public T BarMaker(Bar b) { T t = new T(); t.Convert(b); return t; } } public interface IConvertibleFromBar<T> { T Convert(Bar b); } public class Foo : IConvertibleFromBar<Foo> { public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } edit2: Solution 2: Create a type convertor factory to use: #region library defined code public class Bar {} public class SomeWeirdClass<T, TFactory> where TFactory : IConvertorFactory<Bar, T>, new() { private static TFactory convertor = new TFactory(); public T BarMaker(Bar b) { return convertor.Convert(b); } } public interface IConvertorFactory<TFrom, TTo> { TTo Convert(TFrom from); } #endregion #region user defined code public class BarToFooConvertor : IConvertorFactory<Bar, Foo> { public Foo Convert(Bar from) { return (Foo) from; } } public class Foo { public Foo(int a) {} public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } #endregion public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo, BarToFooConvertor> weird = new SomeWeirdClass<Foo, BarToFooConvertor>(); Foo f = weird.BarMaker(b); } }

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• Is it possible to specify a generic constraint for a type parameter to be convertible FROM another t

  - by fostandy

  Suppose I write a library with the following: public class Bar { /* ... */ } public class SomeWeirdClass<T> where T : ??? { public T BarMaker(Bar b) { // ... play with b T t = (T)b return (T) b; } } Later, I expect users to use my library by defining their own types which are convertible to Bar and using the SomeWeirdClass 'factory'. public class Foo { public static explicit operator Foo(Bar f) { return new Bar(); } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } this will compile if i set where T : Foo but the problem is that I don't know about Foo at the library's compile time, and I actually want something more like where T : some class that can be instantiated, given a Bar Is this possible? From my limited knowledge it does not seem to be, but the ingenuity of the .NET framework and its users always surprises me... This may or not be related to the idea of static interface methods - at least, I can see the value in being able to specify the presence of factory methods to create objects (similar to the same way that you can already perform where T : new()) edit: Solution - thanks to Nick and bzIm - For other readers I'll provide a completed solution as I understand it: edit2: This solution requires Foo to expose a public default constructor. For an even stupider better solution that does not require this see the very bottom of this post. public class Bar {} public class SomeWeirdClass<T> where T : IConvertibleFromBar<T>, new() { public T BarMaker(Bar b) { T t = new T(); t.Convert(b); return t; } } public interface IConvertibleFromBar<T> { T Convert(Bar b); } public class Foo : IConvertibleFromBar<Foo> { public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } edit2: Solution 2: Create a type convertor factory to use: #region library defined code public class Bar {} public class SomeWeirdClass<T, TFactory> where TFactory : IConvertorFactory<Bar, T>, new() { private static TFactory convertor = new TFactory(); public T BarMaker(Bar b) { return convertor.Convert(b); } } public interface IConvertorFactory<TFrom, TTo> { TTo Convert(TFrom from); } #endregion #region user defined code public class BarToFooConvertor : IConvertorFactory<Bar, Foo> { public Foo Convert(Bar from) { return (Foo) from; } } public class Foo { public Foo(int a) {} public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } #endregion public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo, BarToFooConvertor> weird = new SomeWeirdClass<Foo, BarToFooConvertor>(); Foo f = weird.BarMaker(b); } }

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• C++ invalid reference problem

  - by Karol

  Hi all, I'm writing some callback implementation in C++. I have an abstract callback class, let's say: /** Abstract callback class. */ class callback { public: /** Executes the callback. */ void call() { do_call(); }; protected: /** Callback call implementation specific to derived callback. */ virtual void do_call() = 0; }; Each callback I create (accepting single-argument functions, double-argument functions...) is created as a mixin using one of the following: /** Makes the callback a single-argument callback. */ template <typename T> class singleArgumentCallback { protected: /** Callback argument. */ T arg; public: /** Constructor. */ singleArgumentCallback(T arg): arg(arg) { } }; /** Makes the callback a double-argument callback. */ template <typename T, typename V> class doubleArgumentCallback { protected: /** Callback argument 1. */ T arg1; /** Callback argument 2. */ V arg2; public: /** Constructor. */ doubleArgumentCallback(T arg1, V arg2): arg1(arg1), arg2(arg2) { } }; For example, a single-arg function callback would look like this: /** Single-arg callbacks. */ template <typename T> class singleArgFunctionCallback: public callback, protected singleArgumentCallback<T> { /** Callback. */ void (*callbackMethod)(T arg); public: /** Constructor. */ singleArgFunctionCallback(void (*callback)(T), T argument): singleArgumentCallback<T>(argument), callbackMethod(callback) { } protected: void do_call() { this->callbackMethod(this->arg); } }; For user convenience, I'd like to have a method that creates a callback without having the user think about details, so that one can call (this interface is not subject to change, unfortunately): void test3(float x) { std::cout << x << std::endl; } void test5(const std::string& s) { std::cout << s << std::endl; } make_callback(&test3, 12.0f)->call(); make_callback(&test5, "oh hai!")->call(); My current implementation of make_callback(...) is as follows: /** Creates a callback object. */ template <typename T, typename U> callback* make_callback( void (*callbackMethod)(T), U argument) { return new singleArgFunctionCallback<T>(callbackMethod, argument); } Unfortunately, when I call make_callback(&test5, "oh hai!")->call(); I get an empty string on the standard output. I believe the problem is that the reference gets out of scope after callback initialization. I tried using pointers and references, but it's impossible to have a pointer/reference to reference, so I failed. The only solution I had was to forbid substituting reference type as T (for example, T cannot be std::string&) but that's a sad solution since I have to create another singleArgCallbackAcceptingReference class accepting a function pointer with following signature: void (*callbackMethod)(T& arg); thus, my code gets duplicated 2^n times, where n is the number of arguments of a callback function. Does anybody know any workaround or has any idea how to fix it? Thanks in advance!

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• How to get objects to react to touches in Cocos2D?

  - by Wayfarer

  Alright, so I'm starting to learn more about Coco2D, but I'm kinda frusterated. A lot of the tutorials I have found are for outdated versions of the code, so when I look through and see how they do certain things, I can't translate it into my own program, because a lot has changed. With that being said, I am working in the latest version of Coco2d, version 0.99. What I want to do is create a sprite on the screen (Done) and then when I touch that sprite, I can have "something" happen. For now, let's just make an alert go off. Now, I got this code working with the help of a friend. Here is the header file: // When you import this file, you import all the cocos2d classes #import "cocos2d.h" // HelloWorld Layer @interface HelloWorld : CCLayer { CGRect spRect; } // returns a Scene that contains the HelloWorld as the only child +(id) scene; @end And here is the implementation file: // // cocos2d Hello World example // http://www.cocos2d-iphone.org // // Import the interfaces #import "HelloWorldScene.h" #import "CustomCCNode.h" // HelloWorld implementation @implementation HelloWorld +(id) scene { // 'scene' is an autorelease object. CCScene *scene = [CCScene node]; // 'layer' is an autorelease object. HelloWorld *layer = [HelloWorld node]; // add layer as a child to scene [scene addChild: layer]; // return the scene return scene; } // on "init" you need to initialize your instance -(id) init { // always call "super" init // Apple recommends to re-assign "self" with the "super" return value if( (self=[super init] )) { // create and initialize a Label CCLabel* label = [CCLabel labelWithString:@"Hello World" fontName:@"Times New Roman" fontSize:64]; // ask director the the window size CGSize size = [[CCDirector sharedDirector] winSize]; // position the label on the center of the screen label.position = ccp( size.width /2 , size.height/2 ); // add the label as a child to this Layer [self addChild: label]; CCSprite *sp = [CCSprite spriteWithFile:@"test2.png"]; sp.position = ccp(300,200); [self addChild:sp]; float w = [sp contentSize].width; float h = [sp contentSize].height; CGPoint aPoint = CGPointMake([sp position].x - (w/2), [sp position].y - (h/2)); spRect = CGRectMake(aPoint.x, aPoint.y, w, h); CCSprite *sprite2 = [CCSprite spriteWithFile:@"test3.png"]; sprite2.position = ccp(100,100); [self addChild:sprite2]; //[self registerWithTouchDispatcher]; self.isTouchEnabled = YES; } return self; } // on "dealloc" you need to release all your retained objects - (void) dealloc { // in case you have something to dealloc, do it in this method // in this particular example nothing needs to be released. // cocos2d will automatically release all the children (Label) // don't forget to call "super dealloc" [super dealloc]; } - (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; //CGPoint location = [[CCDirector sharedDirector] convertCoordinate:[touch locationInView:touch.view]]; CGPoint location = [touch locationInView:[touch view]]; location = [[CCDirector sharedDirector] convertToGL:location]; if (CGRectContainsPoint(spRect, location)) { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Win" message:@"testing" delegate:nil cancelButtonTitle:@"okay" otherButtonTitles:nil]; [alert show]; [alert release]; NSLog(@"TOUCHES"); } NSLog(@"Touch got"); } However, this only works for 1 object, the sprite which I create the CGRect for. I can't do it for 2 sprites, which I was testing. So my question is this: How can I have all sprites on the screen react to the same event when touched? For my program, the same event needs to be run for all objects of the same type, so that should make it a tad easier. I tried making a subclass of CCNode and over write the method, but that just didn't work at all... so I'm doing something wrong. Help would be appreciated!

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• Issue with Autofac 2 and MVC2 using HttpRequestScoped

  - by Page Brooks

  I'm running into an issue with Autofac2 and MVC2. The problem is that I am trying to resolve a series of dependencies where the root dependency is HttpRequestScoped. When I try to resolve my UnitOfWork (which is Disposable), Autofac fails because the internal disposer is trying to add the UnitOfWork object to an internal disposal list which is null. Maybe I'm registering my dependencies with the wrong lifetimes, but I've tried many different combinations with no luck. The only requirement I have is that MyDataContext lasts for the entire HttpRequest. I've posted a demo version of the code for download here. Autofac modules are set up in web.config Global.asax.cs protected void Application_Start() { string connectionString = "something"; var builder = new ContainerBuilder(); builder.Register(c => new MyDataContext(connectionString)).As<IDatabase>().HttpRequestScoped(); builder.RegisterType<UnitOfWork>().As<IUnitOfWork>().InstancePerDependency(); builder.RegisterType<MyService>().As<IMyService>().InstancePerDependency(); builder.RegisterControllers(Assembly.GetExecutingAssembly()); _containerProvider = new ContainerProvider(builder.Build()); IoCHelper.InitializeWith(new AutofacDependencyResolver(_containerProvider.RequestLifetime)); ControllerBuilder.Current.SetControllerFactory(new AutofacControllerFactory(ContainerProvider)); AreaRegistration.RegisterAllAreas(); RegisterRoutes(RouteTable.Routes); } AutofacDependencyResolver.cs public class AutofacDependencyResolver { private readonly ILifetimeScope _scope; public AutofacDependencyResolver(ILifetimeScope scope) { _scope = scope; } public T Resolve<T>() { return _scope.Resolve<T>(); } } IoCHelper.cs public static class IoCHelper { private static AutofacDependencyResolver _resolver; public static void InitializeWith(AutofacDependencyResolver resolver) { _resolver = resolver; } public static T Resolve<T>() { return _resolver.Resolve<T>(); } } UnitOfWork.cs public interface IUnitOfWork : IDisposable { void Commit(); } public class UnitOfWork : IUnitOfWork { private readonly IDatabase _database; public UnitOfWork(IDatabase database) { _database = database; } public static IUnitOfWork Begin() { return IoCHelper.Resolve<IUnitOfWork>(); } public void Commit() { System.Diagnostics.Debug.WriteLine("Commiting"); _database.SubmitChanges(); } public void Dispose() { System.Diagnostics.Debug.WriteLine("Disposing"); } } MyDataContext.cs public interface IDatabase { void SubmitChanges(); } public class MyDataContext : IDatabase { private readonly string _connectionString; public MyDataContext(string connectionString) { _connectionString = connectionString; } public void SubmitChanges() { System.Diagnostics.Debug.WriteLine("Submiting Changes"); } } MyService.cs public interface IMyService { void Add(); } public class MyService : IMyService { private readonly IDatabase _database; public MyService(IDatabase database) { _database = database; } public void Add() { // Use _database. } } HomeController.cs public class HomeController : Controller { private readonly IMyService _myService; public HomeController(IMyService myService) { _myService = myService; } public ActionResult Index() { // NullReferenceException is thrown when trying to // resolve UnitOfWork here. // Doesn't always happen on the first attempt. using(var unitOfWork = UnitOfWork.Begin()) { _myService.Add(); unitOfWork.Commit(); } return View(); } public ActionResult About() { return View(); } }

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• Problem Registering a Generic Repository with Windsor IoC

  - by Robin

  I’m fairly new to IoC and perhaps my understanding of generics and inheritance is not strong enough for what I’m trying to do. You might find this to be a mess. I have a generic Repository base class: public class Repository<TEntity> where TEntity : class, IEntity { private Table<TEntity> EntityTable; private string _connectionString; private string _userName; public string UserName { get { return _userName; } set { _userName = value; } } public Repository() {} public Repository(string connectionString) { _connectionString = connectionString; EntityTable = (new DataContext(connectionString)).GetTable<TEntity>(); } public Repository(string connectionString, string userName) { _connectionString = connectionString; _userName = userName; EntityTable = (new DataContext(connectionString)).GetTable<TEntity>(); } // Data access methods ... ... } and a SqlClientRepository that inherits Repository: public class SqlClientRepository : Repository<Client> { private Table<Client> ClientTable; private string _connectionString; private string _userName; public SqlClientRepository() {} public SqlClientRepository(string connectionString) : base(connectionString) { _connectionString = connectionString; ClientTable = (new DataContext(connectionString)).GetTable<Client>(); } public SqlClientRepository(string connectionString, string userName) : base(connectionString, userName) { _connectionString = connectionString; _userName = userName; ClientTable = (new DataContext(connectionString)).GetTable<Client>(); } // data access methods unique to Client repository ... } The Repository class provides some generics methods like Save, Delete, etc, that I want all my repository derived classes to share. The TEntity parameter is constrained to the IEntity interface: public interface IEntity { int Id { get; set; } NameValueCollection GetSaveRuleViolations(); NameValueCollection GetDeleteRuleViolations(); } This allows the Repository class to reference these methods within its Save and Delete methods. Unit tests work fine on mock SqlClientRepository instances as well as live unit tests on the real database. However, in the MVC context: public class ClientController : Controller { private SqlClientRepository _clientRepository; public ClientController(SqlClientRepository clientRepository) { this._clientRepository = clientRepository; } public ClientController() { } // ViewResult methods ... ... } ... _clientRepository is always null. I’m using Windor Castle as an IoC container. Here is the configuration: <component id="ClientRepository" service="DomainModel.Concrete.Repository`1[[DomainModel.Entities.Client, DomainModel]], DomainModel" type="DomainModel.Concrete.SqlClientRepository, DomainModel" lifestyle="PerWebRequest"> <parameters> <connectionString>#{myConnStr}</connectionString> </parameters> </component> I’ve tried many variations in the Windsor configuration file. I suspect it’s more of a design flaw in the above code. As I'm looking over my code, it occurs to me that when registering components with an IoC container, perhaps service must always be an interface. Could this be it? Does anybody have a suggestion? Thanks in advance.

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• JMS ConnectionFactory creation error WSVR0073W

  - by scottyab

  I must confess I’m not a JMS aficionado, one of our guys has written a Java webservice client [postcode lookup web service] and from a Remote Java client are calling a Message Driven Bean running in Websphere 6.1, using JMS. Getting the following error when attempted to create the Connection Factory. To which configured within Websphere jms/WSProxyQueueConnectionFactory. WARNING: WSVR0073W. Googling WSVR0073W yields little, the error code is an unknown error. Can anyone shed any light on potential issues creating the connection factory. Code Hashtable env = new Hashtable(); env.put(Context.INITIAL_CONTEXT_FACTORY, contextFactoryName); env.put(Context.PROVIDER_URL, providerURL); env.put("com.ibm.CORBA.ORBInit","com.ibm.ws.sib.client.ORB"); namingContext = new InitialContext(env); System.out.println("callRemoteService: get connectionFactoriy, request/response queues, session. Naming contex env =" + env); // Find everything we need to communicate... connectionFactory = (QueueConnectionFactory) namingContext.lookup(getQueueConnectionFactoryName()); requestQueue = (Queue) namingContext.lookup(getRequestQueueName()); Console output: calling RemoteService with hostname[MyServer:2813] and postcode[M4E 3W1]callRemoteService hostname[MyServer:2813] messess text[M4E 3W1] callRemoteService: get connectionFactoriy, request/response queues, session. Naming contex env ={com.ibm.CORBA.ORBInit=com.ibm.ws.sib.client.ORB, java.naming.provider.url=iiop:// MyServer:2813/, java.naming.factory.initial=com.ibm.websphere.naming.WsnInitialContextFactory} 05-Jan-2011 13:51:04 null null WARNING: WSVR0073W 05-Jan-2011 13:51:05 null null WARNING: jndiGetObjInstErr 05-Jan-2011 13:51:05 null null WARNING: jndiNamingException callRemoteService: closing connections and resources com.ibm.websphere.naming.CannotInstantiateObjectException: Exception occurred while the JNDI NamingManager was processing a javax.naming.Reference object. [Root exception is java.lang.NoClassDefFoundError: Invalid Implementation Key, com.ibm.ws.transaction.NonRecovWSTxManager] at com.ibm.ws.naming.util.Helpers.processSerializedObjectForLookupExt(Helpers.java:1000) at com.ibm.ws.naming.util.Helpers.processSerializedObjectForLookup(Helpers.java:705) at com.ibm.ws.naming.jndicos.CNContextImpl.processResolveResults(CNContextImpl.java:2097) at com.ibm.ws.naming.jndicos.CNContextImpl.doLookup(CNContextImpl.java:1951) at com.ibm.ws.naming.jndicos.CNContextImpl.doLookup(CNContextImpl.java:1866) at com.ibm.ws.naming.jndicos.CNContextImpl.lookupExt(CNContextImpl.java:1556) at com.ibm.ws.naming.jndicos.CNContextImpl.lookup(CNContextImpl.java:1358) at com.ibm.ws.naming.util.WsnInitCtx.lookup(WsnInitCtx.java:172) at javax.naming.InitialContext.lookup(InitialContext.java:450) at com.das.jms.clients.BaseWSProxyClient.callRemoteService(BaseWSProxyClient.java:180) at com.das.jms.clients.RemotePostCodeLookup.findAddress(RemotePostCodeLookup.java:38) at com.das.jms.RemoteServiceAccess.findAddress(RemoteServiceAccess.java:80) at com.das.jms.TestRemoteAccess.testSuccessLookup(TestRemoteAccess.java:20) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37) at java.lang.reflect.Method.invoke(Method.java:599) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:232) at junit.framework.TestSuite.run(TestSuite.java:227) at org.junit.internal.runners.OldTestClassRunner.run(OldTestClassRunner.java:76) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:45) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)com.ibm.websphere.naming.CannotInstantiateObjectException: Exception occurred while the JNDI NamingManager was processing a javax.naming.Reference object. [Root exception is java.lang.NoClassDefFoundError: Invalid Implementation Key, com.ibm.ws.transaction.NonRecovWSTxManager] [[B@4d794d79 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196) Caused by: java.lang.NoClassDefFoundError: Invalid Implementation Key, com.ibm.ws.transaction.NonRecovWSTxManager at com.ibm.ws.Transaction.TransactionManagerFactory.getUOWCurrent(TransactionManagerFactory.java:125) at com.ibm.ws.rsadapter.AdapterUtil.<clinit>(AdapterUtil.java:271) at java.lang.J9VMInternals.initializeImpl(Native Method) at java.lang.J9VMInternals.initialize(J9VMInternals.java:200) at com.ibm.ejs.j2c.ConnectionFactoryBuilderImpl.getObjectInstance(ConnectionFactoryBuilderImpl.java:281) at javax.naming.spi.NamingManager.getObjectInstanceByFactoryInReference(NamingManager.java:480) at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:345) at com.ibm.ws.naming.util.Helpers.processSerializedObjectForLookupExt(Helpers.java:896) ... 31 more

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• UITableView crashes when trying to scroll

  - by Ondrej

  Hi, I have a problem with data in UITableView. I have UIViewController, that contains UITableView outlet and few more things I am using and ... It works :) ... it works lovely, but ... I've created an RSS reader class that is using delegates to deploy the data to the table ... and once again, If I'll just create dummy data in the main controller everything works! problem is with this line: rss.delegate = self; Preview looks a little bit broken than here are those RSS reader files on Google code: (Link to the header file on GoogleCode) (Link to the implementation file on Google code) viewDidLoad function of my controller: IGDataRss20 *rss = [[[IGDataRss20 alloc] init] autorelease]; rss.delegate = self; [rss initWithContentsOfUrl:@"http://rss.cnn.com/rss/cnn_topstories.rss"]; and my delegate methods: - (void)parsingEnded:(NSArray *)result { super.data = [[NSMutableArray alloc] initWithArray:result]; NSLog(@"My Items: %d", [super.data count]); [super.table reloadData]; NSLog(@"Parsing ended"); } (void)parsingError:(NSString *)message { NSLog(@"MyMessage: %@", message); } (void)parsingStarted:(NSXMLParser *)parser { NSLog(@"Parsing started"); } Just to clarify, NSLog(@"Parsing ended"); is being executed and I have 10 items in the array. Ok, here's my RSS reader header file: @class IGDataRss20; @protocol IGDataRss20Delegate @optional (void)parsingStarted:(NSXMLParser *)parser; (void)parsingError:(NSString *)message; (void)parsingEnded:(NSArray *)result; @end @interface IGDataRss20 : NSObject { NSXMLParser *rssParser; NSMutableArray *data; NSMutableDictionary *currentItem; NSString *currentElement; id <IGDataRss20Delegate> delegate; } @property (nonatomic, retain) NSMutableArray *data; @property (nonatomic, assign) id delegate; (void)initWithContentsOfUrl:(NSString *)rssUrl; (void)initWithContentsOfData:(NSData *)inputData; @end And this RSS reader implementation file: #import "IGDataRss20.h" @implementation IGDataRss20 @synthesize data, delegate; (void)initWithContentsOfUrl:(NSString *)rssUrl { self.data = [[NSMutableArray alloc] init]; NSURL *xmlURL = [NSURL URLWithString:rssUrl]; rssParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL]; [rssParser setDelegate:self]; [rssParser setShouldProcessNamespaces:NO]; [rssParser setShouldReportNamespacePrefixes:NO]; [rssParser setShouldResolveExternalEntities:NO]; [rssParser parse]; } (void)initWithContentsOfData:(NSData *)inputData { self.data = [[NSMutableArray alloc] init]; rssParser = [[NSXMLParser alloc] initWithData:inputData]; [rssParser setDelegate:self]; [rssParser setShouldProcessNamespaces:NO]; [rssParser setShouldReportNamespacePrefixes:NO]; [rssParser setShouldResolveExternalEntities:NO]; [rssParser parse]; } (void)parserDidStartDocument:(NSXMLParser *)parser { [[self delegate] parsingStarted:parser]; } (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError { NSString * errorString = [NSString stringWithFormat:@"Unable to parse RSS feed (Error code %i )", [parseError code]]; NSLog(@"Error parsing XML: %@", errorString); if ([parseError code] == 31) NSLog(@"Error code 31 is usually caused by encoding problem."); [[self delegate] parsingError:errorString]; } (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict { currentElement = [elementName copy]; if ([elementName isEqualToString:@"item"]) currentItem = [[NSMutableDictionary alloc] init]; } (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName { if ([elementName isEqualToString:@"item"]) { [data addObject:(NSDictionary *)[currentItem copy]]; } } (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string { if (![currentItem objectForKey:currentElement]) [currentItem setObject:[[[NSMutableString alloc] init] autorelease] forKey:currentElement]; [[currentItem objectForKey:currentElement] appendString:string]; } (void)parserDidEndDocument:(NSXMLParser *)parser { //NSLog(@"RSS array has %d items: %@", [data count], data); [[self delegate] parsingEnded:(NSArray *)self.data]; } (void)dealloc { [data, delegate release]; [super dealloc]; } @end Hope someone will be able to help me as I am becoming to be quite desperate, and I thought I am not already such a greenhorn :) Thanks, Ondrej

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• Exposing model object using bindings in custom NSCell of NSTableView

  - by Hooligancat

  I am struggling trying to perform what I would think would be a relatively common task. I have an NSTableView that is bound to it's array via an NSArrayController. The array controller has it's content set to an NSMutableArray that contains one or more NSObject instances of a model class. What I don't know how to do is expose the model inside the NSCell subclass in a way that is bindings friendly. For the purpose of illustration, we'll say that the object model is a person consisting of a first name, last name, age and gender. Thus the model would appear something like this: @interface PersonModel : NSObject { NSString * firstName; NSString * lastName; NSString * gender; int * age; } Obviously the appropriate setters, getters init etc for the class. In my controller class I define an NSTableView, NSMutableArray and an NSArrayController: @interface ControllerClass : NSObject { IBOutlet NSTableView * myTableView; NSMutableArray * myPersonArray; IBOutlet NSArrayController * myPersonArrayController; } Using Interface Builder I can easily bind the model to the appropriate columns: myPersonArray --> myPersonArrayController --> table column binding This works fine. So I remove the extra columns, leaving one column hidden that is bound to the NSArrayController (this creates and keeps the association between each row and the NSArrayController) so that I am down to one visible column in my NSTableView and one hidden column. I create an NSCell subclass and put the appropriate drawing method to create the cell. In my awakeFromNib I establish the custom NSCell subclass: PersonModel * aCustomCell = [[[PersonModel alloc] init] autorelease]; [[myTableView tableColumnWithIdentifier:@"customCellColumn"] setDataCell:aCustomCell]; This, too, works fine from a drawing perspective. I get my custom cell showing up in the column and it repeats for every managed object in my array controller. If I add an object or remove an object from the array controller the table updates accordingly. However... I was under the impression that my PersonModel object would be available from within my NSCell subclass. But I don't know how to get to it. I don't want to set each NSCell using setters and getters because then I'm breaking the whole model concept by storing data in the NSCell instead of referencing it from the array controller. And yes I do need to have a custom NSCell, so having multiple columns is not an option. Where to from here? In addition to the Google and StackOverflow search, I've done the obligatory walk through on Apple's docs and don't seem to have found the answer. I have found a lot of references that beat around the bush but nothing involving an NSArrayController. The controller makes life very easy when binding to other elements of the model entity (such as a master/detail scenario). I have also found a lot of references (although no answers) when using Core Data, but Im not using Core Data. As per the norm, I'm very grateful for any assistance that can be offered!

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• Why C# doesn't implement indexed properties ?

  - by Thomas Levesque

  I know, I know... Eric Lippert's answer to this kind of question is usually something like "because it wasn't worth the cost of designing, implementing, testing and documenting it". But still, I'd like a better explanation... I was reading this blog post about new C# 4 features, and in the section about COM Interop, the following part caught my attention : By the way, this code uses one more new feature: indexed properties (take a closer look at those square brackets after Range.) But this feature is available only for COM interop; you cannot create your own indexed properties in C# 4.0. OK, but why ? I already knew and regretted that it wasn't possible to create indexed properties in C#, but this sentence made me think again about it. I can see several good reasons to implement it : the CLR supports it (for instance, PropertyInfo.GetValue has an index parameter), so it's a pity we can't take advantage of it in C# it is supported for COM interop, as shown in the article (using dynamic dispatch) it is implemented in VB.NET it is already possible to create indexers, i.e. to apply an index to the object itself, so it would probably be no big deal to extend the idea to properties, keeping the same syntax and just replacing this with a property name It would allow to write that kind of things : public class Foo { private string[] _values = new string[3]; public string Values[int index] { get { return _values[index]; } set { _values[index] = value; } } } Currently the only workaround that I know is to create an inner class (ValuesCollection for instance) that implements an indexer, and change the Values property so that it returns an instance of that inner class. This is very easy to do, but annoying... So perhaps the compiler could do it for us ! An option would be to generate an inner class that implements the indexer, and expose it through a public generic interface : // interface defined in the namespace System public interface IIndexer<TIndex, TValue> { TValue this[TIndex index] { get; set; } } public class Foo { private string[] _values = new string[3]; private class <>c__DisplayClass1 : IIndexer<int, string> { private Foo _foo; public <>c__DisplayClass1(Foo foo) { _foo = foo; } public string this[int index] { get { return _foo._values[index]; } set { _foo._values[index] = value; } } } private IIndexer<int, string> <>f__valuesIndexer; public IIndexer<int, string> Values { get { if (<>f__valuesIndexer == null) <>f__valuesIndexer = new <>c__DisplayClass1(this); return <>f__valuesIndexer; } } } But of course, in that case the property would actually return a IIndexer<int, string>, and wouldn't really be an indexed property... It would be better to generate a real CLR indexed property. What do you think ? Would you like to see this feature in C# ? If not, why ?

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• Dependency Injection: Jetty 7

  - by Malax

  Hi StackOverflow! My application requires several interface implementations which require a Jetty server to do their job. This is, however, not necessarily the case in every implementations of those interfaces so the Jetty server is only a dependency. Since it would be a huge amount of pain to wrap the entire jetty server with all its logging, connector and Handler configurations, I want to inject the server to those implementations with Spring. I decided that injecting the Server class is not a good idea because an implementation could stop the server even if its required at another location. Currently I inject empty HandlerList classes to those implementations and they register their handlers to avoid those problems. The Problem: Those handlers might interfere with other handlers for example: implementation one might register a handler for /foo and implementation two too... problem. Has anyone used Jetty in such an environment? And how could this problem be solved? My XML to clarify my problem: <bean id="jetty" class="org.eclipse.jetty.server.Server" destroy-method="stop"> <property name="connectors"> <list> <bean class="org.eclipse.jetty.server.bio.SocketConnector"> <property name="host" value="10.8.0.46" /> <property name="port" value="9999" /> </bean> </list> </property> <property name="handler"> <bean class="org.eclipse.jetty.server.handler.HandlerCollection"> <property name="handlers"> <list> <ref bean="jetty.handlerList" /> <bean class="org.eclipse.jetty.server.handler.RequestLogHandler"> <property name="requestLog"> <bean class="org.eclipse.jetty.server.NCSARequestLog"> <constructor-arg value="${jetty.logfile}" /> <property name="extended" value="false"/> </bean> </property> </bean> </list> </property> </bean> </property> <property name="sendServerVersion" value="false" /> </bean> <bean id="jetty.handlerList" class="org.eclipse.jetty.server.handler.HandlerList" /> If I require an empty HandlerList I use something like this where com.example.myapp.util.ioc.CreateHandlerListFactory is a org.springframework.beans.factory.FactoryBean which creates a new HandlerList within the given HandlerList. <constructor-arg> <bean class="com.example.myapp.util.ioc.CreateHandlerListFactory"> <constructor-arg ref="jetty.handlerList"/> </bean> </constructor-arg>

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• Resilient backpropagation neural network - question about gradient

  - by Raf

  Hello Guys, First I want to say that I'm really new to neural networks and I don't understand it very good ;) I've made my first C# implementation of the backpropagation neural network. I've tested it using XOR and it looks it work. Now I would like change my implementation to use resilient backpropagation (Rprop - http://en.wikipedia.org/wiki/Rprop). The definition says: "Rprop takes into account only the sign of the partial derivative over all patterns (not the magnitude), and acts independently on each "weight". Could somebody tell me what partial derivative over all patterns is? And how should I compute this partial derivative for a neuron in hidden layer. Thanks a lot UPDATE: My implementation base on this Java code: www_.dia.fi.upm.es/~jamartin/downloads/bpnn.java My backPropagate method looks like this: public double backPropagate(double[] targets) { double error, change; // calculate error terms for output double[] output_deltas = new double[outputsNumber]; for (int k = 0; k < outputsNumber; k++) { error = targets[k] - activationsOutputs[k]; output_deltas[k] = Dsigmoid(activationsOutputs[k]) * error; } // calculate error terms for hidden double[] hidden_deltas = new double[hiddenNumber]; for (int j = 0; j < hiddenNumber; j++) { error = 0.0; for (int k = 0; k < outputsNumber; k++) { error = error + output_deltas[k] * weightsOutputs[j, k]; } hidden_deltas[j] = Dsigmoid(activationsHidden[j]) * error; } //update output weights for (int j = 0; j < hiddenNumber; j++) { for (int k = 0; k < outputsNumber; k++) { change = output_deltas[k] * activationsHidden[j]; weightsOutputs[j, k] = weightsOutputs[j, k] + learningRate * change + momentumFactor * lastChangeWeightsForMomentumOutpus[j, k]; lastChangeWeightsForMomentumOutpus[j, k] = change; } } // update input weights for (int i = 0; i < inputsNumber; i++) { for (int j = 0; j < hiddenNumber; j++) { change = hidden_deltas[j] * activationsInputs[i]; weightsInputs[i, j] = weightsInputs[i, j] + learningRate * change + momentumFactor * lastChangeWeightsForMomentumInputs[i, j]; lastChangeWeightsForMomentumInputs[i, j] = change; } } // calculate error error = 0.0; for (int k = 0; k < outputsNumber; k++) { error = error + 0.5 * (targets[k] - activationsOutputs[k]) * (targets[k] - activationsOutputs[k]); } return error; } So can I use change = hidden_deltas[j] * activationsInputs[i] variable as a gradient (partial derivative) for checking the sing?

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• Cocoa nextEventMatchingMask not receiving NSMouseMoved event

  - by Jonny

  Hello, I created a local event loop and showed up a borderless window (derived from NSPanel), I found in the event loop there's no NSMouseMoved event received, although I can receive Mouse button down/up events. What should I do to get the NSMouseMoved events? I found making the float window as key window can receive the NSMouseMoved events, but I don't want to change key window. And it appears this is possible, because I found after clicking the test App Icon in System Dock Bar, I can receive the mousemoved events, and the key window/mainwindow are unchanged. Here's the my test code: (Create a Cocoa App project names FloatWindowTest, and put a button to link it with the onClick: IBAction). Thanks in advance! -Jonny #import "FloatWindowTestAppDelegate.h" @interface FloatWindow : NSPanel @end @interface FloatWindowContentView : NSView @end @implementation FloatWindowTestAppDelegate @synthesize window; - (void)delayedAction:(id)sender { // What does this function do? // 1. create a float window // 2. create a local event loop // 3. print out the events got from nextEventMatchingMask. // 4. send it to float window. // What is the problem? // In local event loop, althrough the event mask has set NSMouseMovedMask // there's no mouse moved messages received. // FloatWindow* floatWindow = [[FloatWindow alloc] init]; NSEvent* event = [NSApp currentEvent]; NSPoint screenOrigin = [[self window] convertBaseToScreen:[event locationInWindow]]; [floatWindow setFrameTopLeftPoint:screenOrigin]; [floatWindow orderFront:nil]; //Making the float window as Key window will work, however //change active window is not anticipated. //[floatWindow makeKeyAndOrderFront:nil]; BOOL done = NO; while (!done) { NSAutoreleasePool* pool = [NSAutoreleasePool new]; NSUInteger eventMask = NSLeftMouseDownMask| NSLeftMouseUpMask| NSMouseMovedMask| NSMouseEnteredMask| NSMouseExitedMask| NSLeftMouseDraggedMask; NSEvent* event = [NSApp nextEventMatchingMask:eventMask untilDate:[NSDate distantFuture] inMode:NSDefaultRunLoopMode dequeue:YES]; //why I cannot get NSMouseMoved event?? NSLog(@"new event %@", [event description]); [floatWindow sendEvent:event]; [pool drain]; } [floatWindow release]; return; } -(IBAction)onClick:(id)sender { //Tried to postpone the local event loop //after return from button's mouse tracking loop. //but not fixes this problem. [[NSRunLoop currentRunLoop] performSelector:@selector(delayedAction:) target:self argument:nil order:0 modes:[NSArray arrayWithObject:NSDefaultRunLoopMode]]; } @end @implementation FloatWindow - (id)init { NSRect contentRect = NSMakeRect(200,300,200,300); self = [super initWithContentRect:contentRect styleMask:NSTitledWindowMask backing:NSBackingStoreBuffered defer:YES]; if (self) { [self setLevel:NSFloatingWindowLevel]; NSRect frameRect = [self frameRectForContentRect:contentRect]; NSView* view = [[[FloatWindowContentView alloc] initWithFrame:frameRect] autorelease]; [self setContentView:view]; [self setAcceptsMouseMovedEvents:YES]; [self setIgnoresMouseEvents:NO]; } return self; } - (BOOL)becomesKeyOnlyIfNeeded { return YES; } - (void)becomeMainWindow { NSLog(@"becomeMainWindow"); [super becomeMainWindow]; } - (void)becomeKeyWindow { NSLog(@"becomeKeyWindow"); [super becomeKeyWindow]; } @end @implementation FloatWindowContentView - (BOOL)acceptsFirstMouse:(NSEvent *)theEvent { return YES; } - (BOOL)acceptsFirstResponder { return YES; } - (id)initWithFrame:(NSRect)frameRect { self = [super initWithFrame:frameRect]; if (self) { NSTrackingArea* area; area = [[NSTrackingArea alloc] initWithRect:frameRect options:NSTrackingActiveAlways| NSTrackingMouseMoved| NSTrackingMouseEnteredAndExited owner:self userInfo:nil]; [self addTrackingArea:area]; [area release]; } return self; } - (void)drawRect:(NSRect)rect { [[NSColor redColor] set]; NSRectFill([self bounds]); } - (BOOL)becomeFirstResponder { NSLog(@"becomeFirstResponder"); return [super becomeFirstResponder]; } @end

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• Problem Implementing StructureMap in VB.Net Conversion of SharpArchitecture

  - by Monkeeman69

  I work in a VB.Net environment and have recently been tasked with creating an MVC enviroment to use as a base to work from. I decided to convert the latest SharpArchitecture release (Q3 2009) into VB, which on the whole has gone fine after a bit of hair pulling. I came across a problem with Castle Windsor where my custom repository interface (lives in the core/domain project) that was reference in the constructor of my test controller was not getting injected with the concrete implementation (from the data project). I hit a brick wall with this so basically decided to switch out Castle Windsor for StructureMap. I think I have implemented this ok as everything compiles and runs and my controller ran ok when referencing a custom repository interface. It appears now that I have/or cannot now setup my generic interfaces up properly (I hope this makes sense so far as I am new to all this). When I use IRepository(Of T) (wanting it to be injected with a concrete implementation of Repository(Of Type)) in the controller constructor I am getting the following runtime error: "StructureMap Exception Code: 202 No Default Instance defined for PluginFamily SharpArch.Core.PersistenceSupport.IRepository`1[[DebtRemedy.Core.Page, DebtRemedy.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], SharpArch.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b5f559ae0ac4e006" Here are my code excerpts that I am using (my project is called DebtRemedy). My structuremap registry class Public Class DefaultRegistry Inherits Registry Public Sub New() ''//Generic Repositories AddGenericRepositories() ''//Custom Repositories AddCustomRepositories() ''//Application Services AddApplicationServices() ''//Validator [For](GetType(IValidator)).Use(GetType(Validator)) End Sub Private Sub AddGenericRepositories() ''//ForRequestedType(GetType(IRepository(Of ))).TheDefaultIsConcreteType(GetType(Repository(Of ))) [For](GetType(IEntityDuplicateChecker)).Use(GetType(EntityDuplicateChecker)) [For](GetType(IRepository(Of ))).Use(GetType(Repository(Of ))) [For](GetType(INHibernateRepository(Of ))).Use(GetType(NHibernateRepository(Of ))) [For](GetType(IRepositoryWithTypedId(Of ,))).Use(GetType(RepositoryWithTypedId(Of ,))) [For](GetType(INHibernateRepositoryWithTypedId(Of ,))).Use(GetType(NHibernateRepositoryWithTypedId(Of ,))) End Sub Private Sub AddCustomRepositories() Scan(AddressOf SetupCustomRepositories) End Sub Private Shared Sub SetupCustomRepositories(ByVal y As IAssemblyScanner) y.Assembly("DebtRemedy.Core") y.Assembly("DebtRemedy.Data") y.WithDefaultConventions() End Sub Private Sub AddApplicationServices() Scan(AddressOf SetupApplicationServices) End Sub Private Shared Sub SetupApplicationServices(ByVal y As IAssemblyScanner) y.Assembly("DebtRemedy.ApplicationServices") y.With(New FirstInterfaceConvention) End Sub End Class Public Class FirstInterfaceConvention Implements ITypeScanner Public Sub Process(ByVal type As Type, ByVal graph As PluginGraph) Implements ITypeScanner.Process If Not IsConcrete(type) Then Exit Sub End If ''//only works on concrete types Dim firstinterface = type.GetInterfaces().FirstOrDefault() ''//grabs first interface If firstinterface IsNot Nothing Then graph.AddType(firstinterface, type) Else ''//registers type ''//adds concrete types with no interfaces graph.AddType(type) End If End Sub End Class I have tried both ForRequestedType (which I think is now deprecated) and For. IRepository(Of T) lives in SharpArch.Core.PersistenceSupport. Repository(Of T) lives in SharpArch.Data.NHibernate. My servicelocator class Public Class StructureMapServiceLocator Inherits ServiceLocatorImplBase Private container As IContainer Public Sub New(ByVal container As IContainer) Me.container = container End Sub Protected Overloads Overrides Function DoGetInstance(ByVal serviceType As Type, ByVal key As String) As Object Return If(String.IsNullOrEmpty(key), container.GetInstance(serviceType), container.GetInstance(serviceType, key)) End Function Protected Overloads Overrides Function DoGetAllInstances(ByVal serviceType As Type) As IEnumerable(Of Object) Dim objList As New List(Of Object) For Each obj As Object In container.GetAllInstances(serviceType) objList.Add(obj) Next Return objList End Function End Class My controllerfactory class Public Class ServiceLocatorControllerFactory Inherits DefaultControllerFactory Protected Overloads Overrides Function GetControllerInstance(ByVal requestContext As RequestContext, ByVal controllerType As Type) As IController If controllerType Is Nothing Then Return Nothing End If Try Return TryCast(ObjectFactory.GetInstance(controllerType), Controller) Catch generatedExceptionName As StructureMapException System.Diagnostics.Debug.WriteLine(ObjectFactory.WhatDoIHave()) Throw End Try End Function End Class The initialise stuff in my gloabal.asax Dim container As IContainer = New Container(New DefaultRegistry) ControllerBuilder.Current.SetControllerFactory(New ServiceLocatorControllerFactory()) ServiceLocator.SetLocatorProvider(Function() New StructureMapServiceLocator(container)) My test controller Public Class DataCaptureController Inherits BaseController Private ReadOnly clientRepository As IClientRepository() Private ReadOnly pageRepository As IRepository(Of Page) Public Sub New(ByVal clientRepository As IClientRepository(), ByVal pageRepository As IRepository(Of Page)) Check.Require(clientRepository IsNot Nothing, "clientRepository may not be null") Check.Require(pageRepository IsNot Nothing, "pageRepository may not be null") Me.clientRepository = clientRepository Me.pageRepository = pageRepository End Sub Function Index() As ActionResult Return View() End Function The above works fine when I take out everything to do with the pageRepository which is IRepository(Of T). Any help with this would be greatly appreciated.

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• Visitor and templated virtual methods

  - by Thomas Matthews

  In a typical implementation of the Visitor pattern, the class must account for all variations (descendants) of the base class. There are many instances where the same method content in the visitor is applied to the different methods. A templated virtual method would be ideal in this case, but for now, this is not allowed. So, can templated methods be used to resolve virtual methods of the parent class? Given (the foundation): struct Visitor_Base; // Forward declaration. struct Base { virtual accept_visitor(Visitor_Base& visitor) = 0; }; // More forward declarations struct Base_Int; struct Base_Long; struct Base_Short; struct Base_UInt; struct Base_ULong; struct Base_UShort; struct Visitor_Base { virtual void operator()(Base_Int& b) = 0; virtual void operator()(Base_Long& b) = 0; virtual void operator()(Base_Short& b) = 0; virtual void operator()(Base_UInt& b) = 0; virtual void operator()(Base_ULong& b) = 0; virtual void operator()(Base_UShort& b) = 0; }; struct Base_Int : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_Long : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_Short : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_UInt : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_ULong : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_UShort : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; Now that the foundation is laid, here is where the kicker comes in (templated methods): struct Visitor_Cout : public Visitor { template <class Receiver> void operator() (Receiver& r) { std::cout << "Visitor_Cout method not implemented.\n"; } }; Intentionally, Visitor_Cout does not contain the keyword virtual in the method declaration. All the other attributes of the method signatures match the parent declaration (or perhaps specification). In the big picture, this design allows developers to implement common visitation functionality that differs only by the type of the target object (the object receiving the visit). The implementation above is my suggestion for alerts when the derived visitor implementation hasn't implement an optional method. Is this legal by the C++ specification? (I don't trust when some says that it works with compiler XXX. This is a question against the general language.)

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• Synchronizing issue: I want the main thread to be run before another thread but it sometimes doesn´t

  - by Rox

  I have done my own small concurrency framework (just for learning purposes) inspired by the java.util.concurrency package. This is about the Callable/Future mechanism. My code below is the whole one and is compilable and very easy to understand. My problem is that sometimes I run into a deadlock where the first thread (the main thread) awaits for a signal from the other thread. But then the other thread has already notified the main thread before the main thread went into waiting state, so the main thread cannot wake up. FutureTask.get() should always be run before FutureTask.run() but sometimes the run() method (which is called by new thread) runs before the get() method (which is called by main thread). I don´t know how I can prevent that. This is a pseudo code of how I want the two threads to be run. //From main thread: Executor.submit().get() (in get() the main thread waits for new thread to notify) ->submit() calls Executor.execute(FutureTask object) -> execute() starts new thread -> new thread shall notify `main thread` I cannot understand how the new thread can start up and run faster than the main thread that actually starts the new thread. Main.java: public class Main { public static void main(String[] args) { new ExecutorServiceExample(); } public Main() { ThreadExecutor executor = new ThreadExecutor(); Integer i = executor.submit(new Callable<Integer>() { @Override public Integer call() { return 10; } }).get(); System.err.println("Value: "+i); } } ThreadExecutor.java: public class ThreadExecutor { public ThreadExecutor() {} protected <V> RunnableFuture<V> newTaskFor(Callable c) { return new FutureTask<V>(c); } public <V> Future<V> submit(Callable<V> task) { if (task == null) throw new NullPointerException(); RunnableFuture<V> ftask = newTaskFor(task); execute(ftask); return ftask; } public void execute(Runnable r) { new Thread(r).start(); } } FutureTask.java: import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.ReentrantLock; import java.util.logging.Level; import java.util.logging.Logger; public class FutureTask<V> implements RunnableFuture<V> { private Callable<V> callable; private volatile V result; private ReentrantLock lock = new ReentrantLock(); private Condition condition = lock.newCondition(); public FutureTask(Callable callable) { if (callable == null) throw new NullPointerException(); this.callable = callable; } @Override public void run() { acquireLock(); System.err.println("RUN"+Thread.currentThread().getName()); V v = this.callable.call(); set(v); condition.signal(); releaseLock(); } @Override public V get() { acquireLock(); System.err.println("GET "+Thread.currentThread().getName()); try { condition.await(); } catch (InterruptedException ex) { Logger.getLogger(FutureTask.class.getName()).log(Level.SEVERE, null, ex); } releaseLock(); return this.result; } public void set(V v) { this.result = v; } private void acquireLock() { lock.lock(); } private void releaseLock() { lock.unlock(); } } And the interfaces: public interface RunnableFuture<V> extends Runnable, Future<V> { @Override void run(); } public interface Future<V> { V get(); } public interface Callable<V> { V call(); }

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