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• iPhone Apps - The New Business Website?

  That the alternatives of a website or an app are more similar than distinct, and can be seen in the adoption by large websites of iPhone apps. If your target market has elements of mobility, social media involvement and immediacy in decision making, then consider having an iPhone app in addition to and in support of your traditional website.

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• Are there any limitations to using WinRT instead of .Net?

  - by jerrykobes

  From my understanding creating an application that runs on multiple architectures requires virtualization, and virtualization reduces performance since it creates a layer of abstraction. With Windows 8 supporting both Intel and ARM architectures should we expect slower performance with a WinRT app versus a .Net app running on an Intel device? Also, will WinRT support database connectivity and active directory access?

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• MicroApps from The Guardian and Google AppEngine - Both ready for business

  This post is another entry in our on-going series of guest posts from App Engine developers. Today we have the Guardian reporting in on how they're using App...

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• How do I stop unity launcher icon from shaking wobbling, jumping, bouncing, running, and cavorting?

  - by ssu

  When I'm focused and working on something, sometimes an app (like update manager) will decide that it is more important than I am, and start jumping and bouncing and wobbling and waving and generally cavorting around like a spoiled, misbehaving 3-year-old. In general, being very annoying. How do I stop this behavior? I'll get to an app when I get to it - it shouldn't be so needy. I need to work, not spend all day at the service of whatever application pops up.

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• web service host [closed]

  - by elyashiv

  I'm looking for a place to host a cloud service that well manage data from a App I'm developing. The service I need doesn't have any UI (accessed completely through the App software), and well work on only small requests - but hopefully quite a lot of them. I'm looking for something free that well give me the best - in storage and request handling. No specific language, but preferably one of the following: Python, C#, Java. (in this order).

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• ?11.2RAC??????????????

  - by JaneZhang(???)

         ?????,???????????????,???dbca???????,???????????dbca,?????????11.2???????,???????,??dbca??????????????????,????????????????     ????11.2???????RACDB2???,?????RACDB1? ?????rac1,????rac2?     ?11.2?,?????grid?????GI,??oracle????????,????????oracle?????? 1. ??????????????????,?????,???????????:audit_file_dest, background_dump_dest, user_dump_dest ?core_dump_dest????audit_file_dest=/u01/app/oracle/admin/RACDB/adump,?????????,?????????:ORA-09925: Unable to create audit trail fileLinux-x86_64 Error: 2: No such file or directoryAdditional information: 99252. ????????????????????????????:SQL> alter system set instance_number=2 scope=spfile sid='RACDB2';SQL> alter system set thread=2 scope=spfile sid='RACDB2';SQL> alter system set undo_tablespace='UNDOTBS2' scope=spfile sid='RACDB2';SQL> alter system set local_listener='(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=192.0.2.122)(PORT=1521))))' sid='RACDB2'; <=====192.0.2.122???2?VIP 3. ???????DB?$ORACLE_HOME/dbs/init<sid>.ora ?????DB?$ORACLE_HOME/dbs/init<sid>.ora,??????????????init<sid>.ora ????,????spfile???:=======================SPFILE='+DATA/racdb/spfileracdb.ora'??:[oracle@rac1 ~]$ scp $ORACLE_HOME/dbs/initRACDB1.ora rac2:$ORACLE_HOME/dbs/initRACDB2.ora <===????????24.  ??????/etc/oratab,????????????:RACDB2:/u01/app/oracle/product/11.2.0/dbhome_1:N       5.  ???????????: DB?$ORACLE_HOME/dbs/ora<sid>.pwd ????DB?$ORACLE_HOME/dbs/ora<sid>.pwd,??????????????:[oracle@rac1 dbs]$ scp $ORACLE_HOME/dbs/orapwRACDB1 rac2:$ORACLE_HOME/dbs/orapwRACDB2 <==?????26.  ?????????????,????????UNDO TABLESPACE?(??????dbca?????,???????undo tablespace????,?????????)??:SQL>CREATE UNDO TABLESPACE "UNDOTBS2" DATAFILE '/dev/….' SIZE 4096M ;???????:SQL>CREATE UNDO TABLESPACE "UNDOTBS2" DATAFILE '+DATA' SIZE 4096M ;7.  ?????????????,????????redo thread?redo log:??:SQL> alter database add logfile thread 2      group 3 ('/dev/...', '/dev/...') size 1024M,     group 4 ('/dev/...','dev/...') size 1024M;???????:SQL> alter database add logfile thread 2     group 3 ('+DATA','+RECO') size 1024M,     group 4 ('+DATA','+RECO') size 1024M;SQL> alter database enable thread 2; <==????thread8.  ??????????,?????????????:[oracle@rac2 admin]$su - oracle[oracle@rac2 admin]$export ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1[oracle@rac2 admin]$export ORACLE_SID=RACDB2[oracle@rac2 admin]$ sqlplus / as sysdbaSQL> startup <==??????,???????2????????????9. ?????OCR???GI??,?????????????:$srvctl add instance -d <database name> -i <new instance name> -n <new node name>Example of srvctl add instance command:============================[oracle@rac2 ~]$ srvctl add instance -d racdb -i RACDB2 -n rac2  <==????????,????ps -ef|grep smon???[oracle@rac2 dbs]$ ps -ef|grep smonroot      3453     1  1 Jun12 ?        04:03:05 /u01/app/11.2.0/grid/bin/osysmond.bingrid      3727     1  0 Jun12 ?        00:00:19 asm_smon_+ASM2oracle    5343  4543  0 14:06 pts/1    00:00:00 grep smonoracle   28736     1  0 Jun25 ?        00:00:03 ora_smon_RACDB2 <========??????10. ???????:$su - grid[grid@rac2 ~]$ crsctl stat res -t...ora.racdb.db      1        ONLINE  ONLINE       rac1                     Open                      2        OFFLINE OFFLINE             rac2????,??????offline,????????????sqlplus??????sqlplus??????,???srvctl??:[grid@rac2 ~]$ su  - oraclePassword: [oracle@rac2 ~]$ sqlplus / as sysdbaSQL> shutdown immediate;Database closed.Database dismounted.ORACLE instance shut down.SQL> exit[oracle@rac2 ~]$ srvctl start instance -d racdb -i RACDB2[oracle@rac2 ~]$ su - gridPassword: [grid@rac2 ~]$ crsctl stat res -tora.racdb.db      1        ONLINE  ONLINE       rac1                     Open                      2        ONLINE  ONLINE       rac2                     Open                11. ?????????:[oracle@rac2 ~]$ crsctl stat res ora.racdb.db -pNAME=ora.racdb.dbTYPE=ora.database.typeACL=owner:oracle:rwx,pgrp:oinstall:rwx,other::r--ACTION_FAILURE_TEMPLATE=ACTION_SCRIPT=ACTIVE_PLACEMENT=1AGENT_FILENAME=%CRS_HOME%/bin/oraagent%CRS_EXE_SUFFIX%AUTO_START=restoreCARDINALITY=2CHECK_INTERVAL=1CHECK_TIMEOUT=30CLUSTER_DATABASE=trueDATABASE_TYPE=RACDB_UNIQUE_NAME=RACDBDEFAULT_TEMPLATE=PROPERTY(RESOURCE_CLASS=database) PROPERTY(DB_UNIQUE_NAME= CONCAT(PARSE(%NAME%, ., 2), %USR_ORA_DOMAIN%, .)) ELEMENT(INSTANCE_NAME= %GEN_USR_ORA_INST_NAME%) ELEMENT(DATABASE_TYPE= %DATABASE_TYPE%)DEGREE=1DESCRIPTION=Oracle Database resourceENABLED=1FAILOVER_DELAY=0FAILURE_INTERVAL=60FAILURE_THRESHOLD=1GEN_AUDIT_FILE_DEST=/u01/app/oracle/admin/RACDB/adumpGEN_START_OPTIONS=GEN_START_OPTIONS@SERVERNAME(rac1)=openGEN_START_OPTIONS@SERVERNAME(rac2)=openGEN_USR_ORA_INST_NAME=GEN_USR_ORA_INST_NAME@SERVERNAME(rac1)=RACDB1HOSTING_MEMBERS=INSTANCE_FAILOVER=0LOAD=1LOGGING_LEVEL=1MANAGEMENT_POLICY=AUTOMATICNLS_LANG=NOT_RESTARTING_TEMPLATE=OFFLINE_CHECK_INTERVAL=0ONLINE_RELOCATION_TIMEOUT=0ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1ORACLE_HOME_OLD=PLACEMENT=restrictedPROFILE_CHANGE_TEMPLATE=RESTART_ATTEMPTS=2ROLE=PRIMARYSCRIPT_TIMEOUT=60SERVER_POOLS=ora.RACDBSPFILE=+DATA/RACDB/spfileRACDB.oraSTART_DEPENDENCIES=hard(ora.DATA.dg,ora.RECO.dg) weak(type:ora.listener.type,global:type:ora.scan_listener.type,uniform:ora.ons,global:ora.gns) pullup(ora.DATA.dg,ora.RECO.dg)START_TIMEOUT=600STATE_CHANGE_TEMPLATE=STOP_DEPENDENCIES=hard(intermediate:ora.asm,shutdown:ora.DATA.dg,shutdown:ora.RECO.dg)STOP_TIMEOUT=600TYPE_VERSION=3.2UPTIME_THRESHOLD=1hUSR_ORA_DB_NAME=RACDBUSR_ORA_DOMAIN=USR_ORA_ENV=USR_ORA_FLAGS=USR_ORA_INST_NAME=USR_ORA_INST_NAME@SERVERNAME(rac1)=RACDB1USR_ORA_INST_NAME@SERVERNAME(rac2)=RACDB2USR_ORA_OPEN_MODE=openUSR_ORA_OPI=falseUSR_ORA_STOP_MODE=immediateVERSION=11.2.0.3.0???11.2,?OCR???database??,??????,???????????database???????database???????,??????,???????????????ASM????????????  ?:dbca ???????????:????????oracle????dbca:su - oracledbca?? RAC database?? Instance Management?? add an instance???active rac database??????? ??undo?redo??

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• "domain crashed" when creating new Xen instance

  - by user47650

  I have downloaded a Xen virtual machine image from the appscale project, and I am trying to start it up. However once I run the command; xm create -c -f xen.conf The instance immediately crashes and provides no console output. however it produces logs that I have posted below. but this is the error; [2011-03-01 12:34:03 xend.XendDomainInfo 3580] WARNING (XendDomainInfo:1178) Domain has crashed: name=appscale-1.4b id=10. I have managed to mount the root.img file locally and verify that it is actually an ext3 file system. I am running Xen 3.0.3 that is a stock RPM from the CentOS 5 repos; # rpm -qa | grep -i xen xen-libs-3.0.3-105.el5_5.5 xen-3.0.3-105.el5_5.5 xen-libs-3.0.3-105.el5_5.5 kernel-xen-2.6.18-194.32.1.el5 any suggestions on how to proceed with troubleshooting? (i am a newbie to Xen) so far I have enabled console logging, but the log file is empty. ==> domain-builder-ng.log <== xc_dom_allocate: cmdline=" ip=:1.2.3.4::::eth0:dhcp root=/dev/sda1 ro xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console", features="" xc_dom_kernel_file: filename="/boot/vmlinuz-2.6.27-7-server" xc_dom_malloc_filemap : 2284 kB xc_dom_ramdisk_file: filename="/boot/initrd.img-2.6.27-7-server" xc_dom_malloc_filemap : 9005 kB xc_dom_boot_xen_init: ver 3.1, caps xen-3.0-x86_64 xen-3.0-x86_32p xc_dom_parse_image: called xc_dom_find_loader: trying ELF-generic loader ... failed xc_dom_find_loader: trying Linux bzImage loader ... xc_dom_malloc : 9875 kB xc_dom_do_gunzip: unzip ok, 0x234bb2 -> 0x9a4de0 OK elf_parse_binary: phdr: paddr=0x200000 memsz=0x447000 elf_parse_binary: phdr: paddr=0x647000 memsz=0xab888 elf_parse_binary: phdr: paddr=0x6f3000 memsz=0x908 elf_parse_binary: phdr: paddr=0x6f4000 memsz=0x1c2f9c elf_parse_binary: memory: 0x200000 -> 0x8b6f9c elf_xen_parse_note: GUEST_OS = "linux" elf_xen_parse_note: GUEST_VERSION = "2.6" elf_xen_parse_note: XEN_VERSION = "xen-3.0" elf_xen_parse_note: VIRT_BASE = 0xffffffff80000000 elf_xen_parse_note: ENTRY = 0xffffffff8071e200 elf_xen_parse_note: HYPERCALL_PAGE = 0xffffffff80209000 elf_xen_parse_note: FEATURES = "!writable_page_tables|pae_pgdir_above_4gb" elf_xen_parse_note: PAE_MODE = "yes" elf_xen_parse_note: LOADER = "generic" elf_xen_parse_note: unknown xen elf note (0xd) elf_xen_parse_note: SUSPEND_CANCEL = 0x1 elf_xen_parse_note: HV_START_LOW = 0xffff800000000000 elf_xen_parse_note: PADDR_OFFSET = 0x0 elf_xen_addr_calc_check: addresses: virt_base = 0xffffffff80000000 elf_paddr_offset = 0x0 virt_offset = 0xffffffff80000000 virt_kstart = 0xffffffff80200000 virt_kend = 0xffffffff808b6f9c virt_entry = 0xffffffff8071e200 xc_dom_parse_elf_kernel: xen-3.0-x86_64: 0xffffffff80200000 -> 0xffffffff808b6f9c xc_dom_mem_init: mem 1024 MB, pages 0x40000 pages, 4k each xc_dom_mem_init: 0x40000 pages xc_dom_boot_mem_init: called x86_compat: guest xen-3.0-x86_64, address size 64 xc_dom_malloc : 2048 kB ==> xend.log <== [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2114) UUID Created: True [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2115) Devices to release: [], domid = 9 [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2127) Releasing PVFB backend devices ... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:207) XendDomainInfo.create(['domain', ['domid', 9], ['uuid', 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0'], ['vcpus', 1], ['vcpu_avail', 1], ['cpu_cap', 0], ['cpu_weight', 256], ['memory', 1024], ['shadow_memory', 0], ['maxmem', 1024], ['features', ''], ['name', 'appscale-1.4b'], ['on_poweroff', 'destroy'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['image', ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']]], ['cpus', []], ['device', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]], ['device', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']]], ['state', '----c-'], ['shutdown_reason', 'crash'], ['cpu_time', 0.000339131], ['online_vcpus', 1], ['up_time', '0.952092885971'], ['start_time', '1299011639.92'], ['store_mfn', 1169289], ['console_mfn', 1169288]]) [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:329) parseConfig: config is ['domain', ['domid', 9], ['uuid', 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0'], ['vcpus', 1], ['vcpu_avail', 1], ['cpu_cap', 0], ['cpu_weight', 256], ['memory', 1024], ['shadow_memory', 0], ['maxmem', 1024], ['features', ''], ['name', 'appscale-1.4b'], ['on_poweroff', 'destroy'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['image', ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']]], ['cpus', []], ['device', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]], ['device', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']]], ['state', '----c-'], ['shutdown_reason', 'crash'], ['cpu_time', 0.000339131], ['online_vcpus', 1], ['up_time', '0.952092885971'], ['start_time', '1299011639.92'], ['store_mfn', 1169289], ['console_mfn', 1169288]] [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:446) parseConfig: result is {'features': '', 'image': ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']], 'cpus': [], 'vcpu_avail': 1, 'backend': [], 'uuid': 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'on_reboot': 'restart', 'cpu_weight': 256.0, 'memory': 1024, 'cpu_cap': 0, 'localtime': None, 'timer_mode': None, 'start_time': 1299011639.9200001, 'on_poweroff': 'destroy', 'on_crash': 'restart', 'device': [('vif', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]), ('vbd', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']])], 'bootloader': None, 'maxmem': 1024, 'shadow_memory': 0, 'name': 'appscale-1.4b', 'bootloader_args': None, 'vcpus': 1, 'cpu': None} [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1784) XendDomainInfo.construct: None [2011-03-01 12:34:02 xend 3580] DEBUG (balloon:145) Balloon: 3034420 KiB free; need 4096; done. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1953) XendDomainInfo.initDomain: 10 256.0 [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1994) _initDomain:shadow_memory=0x0, maxmem=0x400, memory=0x400. [2011-03-01 12:34:02 xend 3580] DEBUG (balloon:145) Balloon: 3034412 KiB free; need 1048576; done. [2011-03-01 12:34:02 xend 3580] INFO (image:139) buildDomain os=linux dom=10 vcpus=1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:208) domid = 10 [2011-03-01 12:34:02 xend 3580] DEBUG (image:209) memsize = 1024 [2011-03-01 12:34:02 xend 3580] DEBUG (image:210) image = /boot/vmlinuz-2.6.27-7-server [2011-03-01 12:34:02 xend 3580] DEBUG (image:211) store_evtchn = 1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:212) console_evtchn = 2 [2011-03-01 12:34:02 xend 3580] DEBUG (image:213) cmdline = ip=:1.2.3.4::::eth0:dhcp root=/dev/sda1 ro xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console [2011-03-01 12:34:02 xend 3580] DEBUG (image:214) ramdisk = /boot/initrd.img-2.6.27-7-server [2011-03-01 12:34:02 xend 3580] DEBUG (image:215) vcpus = 1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:216) features = ==> domain-builder-ng.log <== xc_dom_build_image: called xc_dom_alloc_segment: kernel : 0xffffffff80200000 -> 0xffffffff808b7000 (pfn 0x200 + 0x6b7 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x200+0x6b7 at 0x2aaaab5f6000 elf_load_binary: phdr 0 at 0x0x2aaaab5f6000 -> 0x0x2aaaaba3d000 elf_load_binary: phdr 1 at 0x0x2aaaaba3d000 -> 0x0x2aaaabae8888 elf_load_binary: phdr 2 at 0x0x2aaaabae9000 -> 0x0x2aaaabae9908 elf_load_binary: phdr 3 at 0x0x2aaaabaea000 -> 0x0x2aaaabb9a004 xc_dom_alloc_segment: ramdisk : 0xffffffff808b7000 -> 0xffffffff82382000 (pfn 0x8b7 + 0x1acb pages) xc_dom_malloc : 160 kB xc_dom_pfn_to_ptr: domU mapping: pfn 0x8b7+0x1acb at 0x2aaab0000000 xc_dom_do_gunzip: unzip ok, 0x8cb5e7 -> 0x1aca210 xc_dom_alloc_segment: phys2mach : 0xffffffff82382000 -> 0xffffffff82582000 (pfn 0x2382 + 0x200 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x2382+0x200 at 0x2aaab1acb000 xc_dom_alloc_page : start info : 0xffffffff82582000 (pfn 0x2582) xc_dom_alloc_page : xenstore : 0xffffffff82583000 (pfn 0x2583) xc_dom_alloc_page : console : 0xffffffff82584000 (pfn 0x2584) nr_page_tables: 0x0000ffffffffffff/48: 0xffff000000000000 -> 0xffffffffffffffff, 1 table(s) nr_page_tables: 0x0000007fffffffff/39: 0xffffff8000000000 -> 0xffffffffffffffff, 1 table(s) nr_page_tables: 0x000000003fffffff/30: 0xffffffff80000000 -> 0xffffffffbfffffff, 1 table(s) nr_page_tables: 0x00000000001fffff/21: 0xffffffff80000000 -> 0xffffffff827fffff, 20 table(s) xc_dom_alloc_segment: page tables : 0xffffffff82585000 -> 0xffffffff8259c000 (pfn 0x2585 + 0x17 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x2585+0x17 at 0x2aaab1ccb000 xc_dom_alloc_page : boot stack : 0xffffffff8259c000 (pfn 0x259c) xc_dom_build_image : virt_alloc_end : 0xffffffff8259d000 xc_dom_build_image : virt_pgtab_end : 0xffffffff82800000 xc_dom_boot_image: called arch_setup_bootearly: doing nothing xc_dom_compat_check: supported guest type: xen-3.0-x86_64 <= matches xc_dom_compat_check: supported guest type: xen-3.0-x86_32p xc_dom_update_guest_p2m: dst 64bit, pages 0x40000 clear_page: pfn 0x2584, mfn 0x11d788 clear_page: pfn 0x2583, mfn 0x11d789 xc_dom_pfn_to_ptr: domU mapping: pfn 0x2582+0x1 at 0x2aaab1ce2000 start_info_x86_64: called setup_hypercall_page: vaddr=0xffffffff80209000 pfn=0x209 domain builder memory footprint allocated malloc : 12139 kB anon mmap : 0 bytes mapped file mmap : 11289 kB domU mmap : 35 MB arch_setup_bootlate: shared_info: pfn 0x0, mfn 0xd6fe1 shared_info_x86_64: called vcpu_x86_64: called vcpu_x86_64: cr3: pfn 0x2585 mfn 0x11d787 launch_vm: called, ctxt=0x97b21f8 xc_dom_release: called ==> xend.log <== [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:114) DevController: writing {'mac': '00:16:3B:72:10:E4', 'handle': '0', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/vif/10/0'} to /local/domain/10/device/vif/0. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:116) DevController: writing {'domain': 'appscale-1.4b', 'handle': '0', 'script': '/etc/xen/scripts/vif-bridge', 'state': '1', 'frontend': '/local/domain/10/device/vif/0', 'mac': '00:16:3B:72:10:E4', 'online': '1', 'frontend-id': '10'} to /local/domain/0/backend/vif/10/0. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:634) Checking for duplicate for uname: /local/xen/domains/appscale1.4/root.img [file:/local/xen/domains/appscale1.4/root.img], dev: sda1:disk, mode: w [2011-03-01 12:34:02 xend 3580] DEBUG (blkif:27) exception looking up device number for sda1:disk: [Errno 2] No such file or directory: '/dev/sda1:disk' [2011-03-01 12:34:02 xend 3580] DEBUG (blkif:27) exception looking up device number for sda1: [Errno 2] No such file or directory: '/dev/sda1' [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:114) DevController: writing {'virtual-device': '2049', 'device-type': 'disk', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/vbd/10/2049'} to /local/domain/10/device/vbd/2049. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:116) DevController: writing {'domain': 'appscale-1.4b', 'frontend': '/local/domain/10/device/vbd/2049', 'format': 'raw', 'dev': 'sda1', 'state': '1', 'params': '/local/xen/domains/appscale1.4/root.img', 'mode': 'w', 'online': '1', 'frontend-id': '10', 'type': 'file'} to /local/domain/0/backend/vbd/10/2049. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:993) Storing VM details: {'shadow_memory': '0', 'uuid': 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'on_reboot': 'restart', 'start_time': '1299011642.74', 'on_poweroff': 'destroy', 'name': 'appscale-1.4b', 'xend/restart_count': '0', 'vcpus': '1', 'vcpu_avail': '1', 'memory': '1024', 'on_crash': 'restart', 'image': "(linux (kernel /boot/vmlinuz-2.6.27-7-server) (ramdisk /boot/initrd.img-2.6.27-7-server) (ip :1.2.3.4::::eth0:dhcp) (root '/dev/sda1 ro') (args 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console'))", 'maxmem': '1024'} [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1028) Storing domain details: {'console/ring-ref': '1169288', 'console/port': '2', 'name': 'appscale-1.4b', 'console/limit': '1048576', 'vm': '/vm/d5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'domid': '10', 'cpu/0/availability': 'online', 'memory/target': '1048576', 'store/ring-ref': '1169289', 'store/port': '1'} [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:158) Waiting for devices vif. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:164) Waiting for 0. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1250) XendDomainInfo.handleShutdownWatch [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vif/10/0/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vif/10/0/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:523) hotplugStatusCallback 1. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices usb. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vbd. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:164) Waiting for 2049. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vbd/10/2049/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vbd/10/2049/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:523) hotplugStatusCallback 1. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices irq. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vkbd. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vfb. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices pci. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices ioports. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices tap. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vtpm. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] WARNING (XendDomainInfo:1178) Domain has crashed: name=appscale-1.4b id=10. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] ERROR (XendDomainInfo:2654) VM appscale-1.4b restarting too fast (2.275545 seconds since the last restart). Refusing to restart to avoid loops. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2189) XendDomainInfo.destroy: domid=10 ==> xen-hotplug.log <== Nothing to flush. ==> xend.log <== [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2114) UUID Created: True [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2115) Devices to release: [], domid = 10 [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2127) Releasing PVFB backend devices ... And this is the xen.conf file that I am using; # cat xen.conf # Configuration file for the Xen instance AppScale, created # bn VMBuilder kernel = '/boot/vmlinuz-2.6.27-7-server' ramdisk = '/boot/initrd.img-2.6.27-7-server' memory = 1024 vcpus = 1 root = '/dev/sda1 ro' disk = [ 'file:/local/xen/domains/appscale1.4/root.img,sda1,w', ] name = 'appscale-1.4b' dhcp = 'dhcp' vif = [ 'mac=00:16:3B:72:10:E4' ] on_poweroff = 'destroy' on_reboot = 'restart' on_crash = 'restart' extra = 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console'

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• SQL SERVER – What is Spatial Database? – Developing with SQL Server Spatial and Deep Dive into Spati

  - by pinaldave

  What is Spatial Database? A spatial database is a database that is optimized to store and query data related to objects in space, including points, lines and polygons. While typical databases can understand various numeric and character types of data, additional functionality needs to be added for databases to process spatial data types. (Source: Wikipedia) Today I will be talking about the same subject at Microsoft TechEd India. If you want to learn about how to spatial aspect of data and how to integrate them with SQL Server this is the perfect session for you. Spatial is very special concept of SQL Server and I really like how it is implemented in SQL Server. In general Performance Tuning and Query Optimization is something I always have enjoyed in my professional life. Index are my best friends and many time, by implementing and many time by removing I have improved the performance of the system. In this session, I will be talking about Index along with Spatial Data. As Spatial Database is very interesting concept, I will cover super short but very interesting 10 quick slides about this subject. I will make sure in very first 20 mins, you will understand following topics Introduction to Spatial Database One line definition Understanding Spatial Indexing Index Internals Query/Performance Tuning Query Hinting/Cost Analysis Spatial Index Catalog Views Performance Troubleshooting Finding Optimal Index using Spatial Index SP Common Errors Index Maintenance This slides decks will be followed by around 30 mins demo which will have story of geometry, geography, index internals and performance tuning. If you are interested in learning how GIS works and how SQL Server out of the box supports this wonderful tools, you will really like how the story is told. I am sure all people who attend the event will know how the Bangalore is positioned on the map of India. I will take example of Bangalore and Hyderabad and demonstrate how index can improve the performance. Well there are lots of story to tell in the session, and I will be opening this session with the beautiful script of Botticelli’s Birth of Venus created by Michael J. Swart. I will also demonstrate few real life scenario where I will be talking about Spatial Database and its usage. Do not miss this session. At the end of session there will be book awarded to best participant. My session details: Session 3: Developing with SQL Server Spatial and Deep Dive into Spatial Indexing Date: April 14, 2010 Time: 5:00pm-6:00pm Microsoft SQL Server 2008 delivers new spatial data types that enable you to consume, use, and extend location-based data through spatial-enabled applications. Attend this session to learn how to use spatial functionality in next version of SQL Server to build and optimize spatial queries. This session outlines the new geography data type to store geodetic spatial data and perform operations on it, use the new geometry data type to store planar spatial data and perform operations on it, take advantage of new spatial indexes for high performance queries, use the new spatial results tab to quickly and easily view spatial query results directly from within Management Studio, extend spatial data capabilities by building or integrating location-enabled applications through support for spatial standards and specifications and much more. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL, Technology Tagged: Spatial Database

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• asynchrony is viral

  - by Daniel Moth

  It is becoming hard to write code today without introducing some form of asynchrony and, if you are using .NET (e.g. for Windows Phone 8 or Windows Store apps), that means sooner or later you have to await something and mark your method as async. My most recent examples included introducing speech recognition in my Translator By Moth phone app where I had to await mySpeechRecognizerUI.RecognizeWithUIAsync() and when moving that code base to a Windows Store project just to show a MessageBox I had to await myMessageDialog.ShowAsync(). Any time you need to invoke an asynchronous method in your code, you have a choice to make: kick off the operation but don’t wait for it to complete (otherwise known as fire-and-forget), synchronously wait for it to complete (which will entail blocking, which can be bad, especially on a UI thread), or asynchronously wait for it to complete before continuing on with the rest of the method’s work. In most cases, you want the latter, and the await keyword makes that trivial to implement.  When you use the magical await keyword in front of an API call, then you typically have to make additional changes to your code: This await usage is within a method of course, and now you have to annotate that method with async. Furthermore, you have to change the return type of the method you just annotated so it returns a Task (if it previously returned void), or Task<myOldReturnType> (if it previously returned myOldReturnType). Note that if it returns void, in some cases you could cheat and stop there. Furthermore, any method that called this method you just annotated with async will now also be invoking an asynchronous operation, so you have to make that change in the body of the caller method to introduce the await keyword before the call to the method. …you guessed it, you now have to change this caller method to be annotated with async and have its return types tweaked... …and it goes on virally… At some point you reach the root of your user code, e.g. a GUI event handler, and whoever calls that void method can already deal with the fact that you marked it as async and the viral introduction of the keywords stops there… This is all wonderful progress and a very powerful mechanism, and I just wish someone had written a refactoring tool to take care of this… anyone? I mentioned earlier that you have a choice when invoking an asynchronous operation. If the first time you encounter this you wish to localize the impact of all these changes and essentially try to turn the asynchronous behavior into synchronous by blocking - don't! For reasons why you don't want to do that, read Toub's excellent blog post (and check out the rest of his blog with gems on async programming starting with the Async FAQ). Just embrace the pattern knowing that when you use one instance of an await, you'll propagate the change all the way to the root user code method, e.g. typically an event handler. Related aside: I just finished re-writing my MessageBox wrapper class for Phone projects, including making it work in Windows Store projects, and it does expect you to use it with an await :-). I'll share that in an upcoming post for those of you that have the same need… Comments about this post by Daniel Moth welcome at the original blog.

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• Prepping the Raspberry Pi for Java Excellence (part 1)

  - by HecklerMark

  I've only recently been able to begin working seriously with my first Raspberry Pi, received months ago but hastily shelved in preparation for JavaOne. The Raspberry Pi and other diminutive computing platforms offer a glimpse of the potential of what is often referred to as the embedded space, the "Internet of Things" (IoT), or Machine to Machine (M2M) computing. I have a few different configurations I want to use for multiple Raspberry Pis, but for each of them, I'll need to perform the following common steps to prepare them for their various tasks: Load an OS onto an SD card Get the Pi connected to the network Load a JDK I've been very happy to see good friend and JFXtras teammate Gerrit Grunwald document how to do these things on his blog (link to article here - check it out!), but I ran into some issues configuring wi-fi that caused me some needless grief. Not knowing if any of the pitfalls were caused by my slightly-older version of the Pi and not being able to find anything specific online to help me get past it, I kept chipping away at it until I broke through. The purpose of this post is to (hopefully) help someone else recognize the same issues if/when they encounter them and work past them quickly. There is a great resource page here that covers several ways to get the OS on an SD card, but here is what I did (on a Mac): Plug SD card into reader on/in Mac Format it (FAT32) Unmount it (diskutil unmountDisk diskn, where n is the disk number representing the SD card) Transfer the disk image for Debian to the SD card (dd if=2012-08-08-wheezy-armel.img of=/dev/diskn bs=1m) Eject the card from the Mac (diskutil eject diskn) There are other ways, but this is fairly quick and painless, especially after you do it several times. Yes, I had to do that dance repeatedly (minus formatting) due to the wi-fi issues, as it kept killing the ability of the Pi to boot. You should be able to dramatically reduce the number of OS loads you do, though, if you do a few things with regard to your wi-fi. Firstly, I strongly recommend you purchase the Edimax EW-7811Un wi-fi adapter. This adapter/chipset has been proven with the Raspberry Pi, it's tiny, and it's cheap. Avoid unnecessary aggravation and buy this one! Secondly, visit this page for a script and instructions regarding how to configure your new wi-fi adapter with your Pi. Here is the rub, though: there is a missing step. At least for my combination of Pi version, OS version, and uncanny gift of timing and luck there was. :-) Here is the sequence of steps I used to make the magic happen: Plug your newly-minted SD card (with OS) into your Pi and connect a network cable (for internet connectivity) Boot your Pi. On the first boot, do the following things: Opt to have it use all space on the SD card (will require a reboot eventually) Disable overscan Set your timezone Enable the ssh server Update raspi-config Reboot your Pi. This will reconfigure the SD to use all space (see above). After you log in (UID: pi, password: raspberry), upgrade your OS. This was the missing step for me that put a merciful end to the repeated SD card re-imaging and made the wi-fi configuration trivial. To do so, just type sudo apt-get upgrade and give it several minutes to complete. Pour yourself a cup of coffee and congratulate yourself on the time you've just saved.  ;-) With the OS upgrade finished, now you can follow Mr. Engman's directions (to the letter, please see link above), download his script, and let it work its magic. One aside: I plugged the little power-sipping Edimax directly into the Pi and it worked perfectly. No powered hub needed, at least in my configuration. To recap, that OS upgrade (at least at this point, with this combination of OS/drivers/Pi version) is absolutely essential for a smooth experience. Miss that step, and you're in for hours of "fun". Save yourself! I'll pick up next time with more of the Java side of the RasPi configuration, but as they say, you have to cross the moat to get into the castle. Hopefully, this will help you do just that. Until next time! All the best, Mark 

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• Asp.net Session State Revisited

  - by karan@dotnet

  Every now and then I see doubts and queries which I believe is the most discussed topic in the .net environment - Asp.net Sessions. So what really are they, why are they needed and what does browser and .net do with it. These and some of the other questions I hope to answer with this post. Because of the stateless nature of the HTTP protocol there is always a need of state management in a web application. There are many other ways to store data but I feel Session state is amongst the most powerful one. The ASP.NET session state is a technology that lets you store server-side, user-specific data. Our web applications can then use data to process request from the user for which the session state was instantiated. So when does a session is first created? When we start a asp.net application a non-expiring cookie is created and its called as ASP.NET_SessionId. Basically there are two methods for this depending upon how you configure this setting in your config file. The session ID can be a part of cookie as discussed above(called as ASP.NET_SessionId) or it is embedded in the browser’s URL. For the latter part we have to set cookie-less session in our web.config file. These Session ID’s are 120-bit random number that is represented by 20-character string. The cookie will be alive until you close your browser. If you browse from one app to another within the same domain, then both the apps will use the same session ID to track the session state. Why reuse? so that you don’t have to create a new session ID for each request. One can abandon one particular Session by calling Session.Abandon() which will stop the page processing and clear out the session data. A subsequent page request causes a brand new session object to be instantiated. So what happened to my cookie? Well the session cookie is still there even when one Session.Abandon() is called and another session object is created. The Session.Abandon() lets you clear out your session state without waiting for session timeout. By default, this time-out is a 20-minute sliding expiration. This expiration is refreshed every time that the user makes a request to the Web site and presents the session ID cookie. The Abandon method sets a flag in the session state object that indicates that the session state should be abandoned. If your app does not have global.asax then your session cookie will be killed at the end of each page request. So you need to have a global.asax file and Session_Start() handler to make sure that the session cookie will remain intact once its issued after the first page hit. The runtime invokes global.asax’s Session_OnEnd() when you call Session.Abandon() or the session times out. The session manager stores session data in HttpCache with sliding expiration where this timeout can be configured in the <sessionState> of web.config file. When the timeout is up the HttpCache will remove the session state object. Sometimes we want particular pages not to time out as compared to other pages in our applications. We can handle this in two ways. First, we can set a timer or may be a JavaScript function that refreshes the page after fixed intervals of time. The only thing being the page being cached locally and then the request is not made to the server so to prevent that you can add this to your page: <%@ OutputCache Location="None" VaryByParam="None" %> Second approach is to move your page into its own folder and then add a web.config to that folder to control the timeout. Also not all pages in your application will need access to session state. For those pages that do not, you can indicate that session state is not needed and prevent session data from being fetched from the store in requests to these pages. You can disable the session state at page level like this:<%@ Page EnableSessionState="False" %>tbc…

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• std::map for storing static const Objects

  - by Sean M.

  I am making a game similar to Minecraft, and I am trying to fine a way to keep a map of Block objects sorted by their id. This is almost identical to the way that Minecraft does it, in that they declare a bunch of static final Block objects and initialize them, and then the constructor of each block puts a reference of that block into whatever the Java equivalent of a std::map is, so there is a central place to get ids and the Blocks with those ids. The problem is, that I am making my game in C++, and trying to do the exact same thing. In Block.h, I am declaring the Blocks like so: //Block.h public: static const Block Vacuum; static const Block Test; And in Block.cpp I am initializing them like so: //Block.cpp const Block Block::Vacuum = Block("Vacuum", 0, 0); const Block Block::Test = Block("Test", 1, 0); The block constructor looks like this: Block::Block(std::string name, uint16 id, uint8 tex) { //Check for repeat ids if (IdInUse(id)) { fprintf(stderr, "Block id %u is already in use!", (uint32)id); throw std::runtime_error("You cannot reuse block ids!"); } _id = id; //Check for repeat names if (NameInUse(name)) { fprintf(stderr, "Block name %s is already in use!", name); throw std::runtime_error("You cannot reuse block names!"); } _name = name; _tex = tex; //fprintf(stdout, "Using texture %u\n", _tex); _transparent = false; _solidity = 1.0f; idMap[id] = this; nameMap[name] = this; } And finally, the maps that I'm using to store references of Blocks in relation to their names and ids are declared as such: std::map<uint16, Block*> Block::idMap = std::map<uint16, Block*>(); //The map of block ids std::map<std::string, Block*> Block::nameMap = std::map<std::string, Block*>(); //The map of block names The problem comes when I try to get the Blocks in the maps using a method called const Block* GetBlock(uint16 id), where the last line is return idMap.at(id);. This line returns a Block with completely random values like _visibility = 0xcccc and such like that, found out through debugging. So my question is, is there something wrong with the blocks being declared as const obejcts, and then stored at pointers and accessed later on? The reason I cant store them as Block& is because that makes a copy of the Block when it is entered, so the block wouldn't have any of the attributes that could be set afterwards in the constructor of any child class, so I think I need to store them as a pointer. Any help is greatly appreciated, as I don't fully understand pointers yet. Just ask if you need to see any other parts of the code.

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• Bad Spot to Be In: Playing Catch-up with Mobile Advertising

  - by Mike Stiles

  You probably noticed, there’s a mass migration going on from online desktop/laptop usage to smartphone/tablet usage.  It’s an indicator of how we live our lives in the modern world: always on the go, with no intention of being disconnected while out there. Consequently, paid as it relates to mobile advertising is taking the social spotlight. eMarketer estimated that in 2013, US adults would spend about 2 hours, 21 minutes a day on mobile, not counting talking time. More people in the world own smartphones than own toothbrushes (bad news I suppose if you’re marketing toothpaste). They’re using those mobile devices to access social networks, consuming at least 17% of their mobile time on them. Frankly, you don’t need a deep dive into mobile usage stats to know what’s going on. Just look around you in any store, venue or coffee shop. It’s really obvious…our mobile devices are now where we “are,” so that’s where marketers can increasingly reach us. And it’s a smart place for them to do just that. Mobile devices can be viewed more and more as shopping facilitators. Usually when someone is on mobile, they are not in passive research mode. They are likely standing near a store or in front of a product, using their mobile to seek reassurance that buying that product is the right move. They are the hottest of hot prospects. Consider that 4 out of 5 consumers use smartphones to shop, 52% of Americans use mobile devices for in-store for research, 70% of mobile searches lead to online action inside of an hour, and people that find you on mobile convert at almost 3x the rate as those that find you on desktop or laptop. But what are marketers doing? Enter statistics from Mary Meeker’s latest State of the Internet report. Common sense says you buy advertising where people are spending their eyeball time, right? But while mobile is 20% of media use and rising, the ad spend there is 4%. Conversely, while print usage is at 5% and falling, ad spend there is 19%. We all love nostalgia, but come on. There are reasons marketing dollar migration to mobile has not matched user migration, including the availability of mobile ad products and the ability to measure user response to mobile ads. But interesting things are happening now. First came Facebook’s mobile ad, which let app developers pay to get potential downloads. Then their mobile ad network was announced at F8, allowing marketers to target users across non-Facebook apps while leveraging the wealth of diverse data Facebook has on those users, a big deal since Nielsen has pointed out mobile apps make up 89% of the media time spent on mobile. Twitter has a similar play in motion with their MoPub acquisition. And now mobile deeplinks have arrived, which can take users straight to sub-pages of mobile apps for a faster, more direct shopper/researcher user experience. The sooner the gratification, the smoother and faster the conversion. To be clear, growth in mobile ad spending is well underway. After posting $13.1 billion in 2013, Gartner expects global mobile ad spending to reach $18 billion this year, then go to $41.9 billion by 2017. Cheap smartphones and data plans are spreading worldwide, further fueling the shift to mobile. Mobile usage in India alone should grow 400% by 2018. And, of course, there’s the famous statistic that mobile should overtake desktop Internet usage this year. How can we as marketers mess up this opportunity? Two ways. We could position ourselves in perpetual “catch-up” mode and keep spending ad dollars where the public used to be. And we could annoy mobile users with horrid old-school marketing practices. Two-thirds of users told Forrester they think interruptive in-app ads are more annoying than TV ads. Make sure your brand’s social marketing technology platform is delivering a crystal clear picture of your social connections so the mobile touch point is highly relevant, mobile optimized, and delivering real value and satisfying experiences. Otherwise, all we’ve done is find a new way to be unwanted. @mikestiles @oraclesocialPhoto: Kate Mallatratt, freeimages.com

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• Normalisation and 'Anima notitia copia' (Soul of the Database)

  - by Phil Factor

  (A Guest Editorial for Simple-Talk) The other day, I was staring  at the sys.syslanguages  table in SQL Server with slightly-raised eyebrows . I’d just been reading Chris Date’s  interesting book ‘SQL and Relational Theory’. He’d made the point that you’re not necessarily doing relational database operations by using a SQL Database product.  The same general point was recently made by Dino Esposito about ASP.NET MVC.  The use of ASP.NET MVC doesn’t guarantee you a good application design: It merely makes it possible to test it. The way I’d describe the sentiment in both cases is ‘you can hit someone over the head with a frying-pan but you can’t call it cooking’. SQL enables you to create relational databases. However,  even if it smells bad, it is no crime to do hideously un-relational things with a SQL Database just so long as it’s necessary and you can tell the difference; not only that but also only if you’re aware of the risks and implications. Naturally, I’ve never knowingly created a database that Codd would have frowned at, but around the edges are interfaces and data feeds I’ve written  that have caused hissy fits amongst the Normalisation fundamentalists. Part of the problem for those who agonise about such things  is the misinterpretation of Atomicity.  An atomic value is one for which, in the strange virtual universe you are creating in your database, you don’t have any interest in any of its component parts.  If you aren’t interested in the electrons, neutrinos,  muons,  or  taus, then  an atom is ..er.. atomic. In the same way, if you are passed a JSON string or XML, and required to store it in a database, then all you need to do is to ask yourself, in your role as Anima notitia copia (Soul of the database) ‘have I any interest in the contents of this item of information?’.  If the answer is ‘No!’, or ‘nequequam! Then it is an atomic value, however complex it may be.  After all, you would never have the urge to store the pixels of images individually, under the misguided idea that these are the atomic values would you?  I would, of course,  ask the ‘Anima notitia copia’ rather than the application developers, since there may be more than one application, and the applications developers may be designing the application in the absence of full domain knowledge, (‘or by the seat of the pants’ as the technical term used to be). If, on the other hand, the answer is ‘sure, and we want to index the XML column’, then we may be in for some heavy XML-shredding sessions to get to store the ‘atomic’ values and ensure future harmony as the application develops. I went back to looking at the sys.syslanguages table. It has a months column with the months in a delimited list January,February,March,April,May,June,July,August,September,October,November,December This is an ordered list. Wicked? I seem to remember that this value, like shortmonths and days, is treated as a ‘thing’. It is merely passed off to an external  C++ routine in order to format a date in a particular language, and never accessed directly within the database. As far as the database is concerned, it is an atomic value.  There is more to normalisation than meets the eye.

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• Big Data – Operational Databases Supporting Big Data – Columnar, Graph and Spatial Database – Day 14 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the Key-Value Pair Databases and Document Databases in the Big Data Story. In this article we will understand the role of Columnar, Graph and Spatial Database supporting Big Data Story. Now we will see a few of the examples of the operational databases. Relational Databases (The day before yesterday’s post) NoSQL Databases (The day before yesterday’s post) Key-Value Pair Databases (Yesterday’s post) Document Databases (Yesterday’s post) Columnar Databases (Tomorrow’s post) Graph Databases (Today’s post) Spatial Databases (Today’s post) Columnar Databases  Relational Database is a row store database or a row oriented database. Columnar databases are column oriented or column store databases. As we discussed earlier in Big Data we have different kinds of data and we need to store different kinds of data in the database. When we have columnar database it is very easy to do so as we can just add a new column to the columnar database. HBase is one of the most popular columnar databases. It uses Hadoop file system and MapReduce for its core data storage. However, remember this is not a good solution for every application. This is particularly good for the database where there is high volume incremental data is gathered and processed. Graph Databases For a highly interconnected data it is suitable to use Graph Database. This database has node relationship structure. Nodes and relationships contain a Key Value Pair where data is stored. The major advantage of this database is that it supports faster navigation among various relationships. For example, Facebook uses a graph database to list and demonstrate various relationships between users. Neo4J is one of the most popular open source graph database. One of the major dis-advantage of the Graph Database is that it is not possible to self-reference (self joins in the RDBMS terms) and there might be real world scenarios where this might be required and graph database does not support it. Spatial Databases  We all use Foursquare, Google+ as well Facebook Check-ins for location aware check-ins. All the location aware applications figure out the position of the phone with the help of Global Positioning System (GPS). Think about it, so many different users at different location in the world and checking-in all together. Additionally, the applications now feature reach and users are demanding more and more information from them, for example like movies, coffee shop or places see. They are all running with the help of Spatial Databases. Spatial data are standardize by the Open Geospatial Consortium known as OGC. Spatial data helps answering many interesting questions like “Distance between two locations, area of interesting places etc.” When we think of it, it is very clear that handing spatial data and returning meaningful result is one big task when there are millions of users moving dynamically from one place to another place & requesting various spatial information. PostGIS/OpenGIS suite is very popular spatial database. It runs as a layer implementation on the RDBMS PostgreSQL. This makes it totally unique as it offers best from both the worlds. Courtesy: mushroom network Tomorrow In tomorrow’s blog post we will discuss about very important components of the Big Data Ecosystem – Hive. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• First Impressions of a MacBook (from a PC guy)

  - by dgreen

  Disclaimer: I've been a PC guy my entire working career. I'd probably characterize myself as a power user. Never afraid to bust out the console line. But working with a Mac is totally foreign to me. So for those Mac guys who are curious, this is how your world appears from the outside to a computer literate person :)My Macbook Air has arrived! And it's a thing of beauty:First, the specs: 13" MacBook Air, 2.0GHz Core i7 processor. Upgraded to 8GB of RAM for an additional $100, SSD flash storage  = 256GB. The plan is ultimately to use this baby for some iOS development but also some decent lifting in Windows with Visual Studio. Done a lot of reading  and between VMWare Fusion, Parallels and Bootcamp...I'm going to go with VMWare Fusion for $49.99And now my impressions (please re-read disclaimer before proceeding!):I open the box and am trying to understand exactly how the magsafe connector works (and how to disconnect it).  Why does it have two socket outlet plugs? Who knows.  I feel like Hansel in Zoolander. The files are "in" the computer.Stuck in my external hard drive (usb). So how do I get to the files? To the Googles!Argh...it can't read my external NTFS drive. Fat32 can't support field over 4GB…problematic since some of my existing VMWare image files are much larger than 4GB. Didn't see this coming.Three year old loves iPhoto. Super easy to use. Don't even know what I'm doing but I've already (accidentally) discovered the image filtering options. Fun stuff.First thing I downloaded ever => Chrome. I need something to ground me, something familiar. My token, if you will (sorry, gratuitous Inception joke).Ok, I get it… Finder == windows explorer. But where is my hierarchical structure? I miss the tree :(On that note, yeah…how do I see what "path" my files reside in? I'm afraid to know the answer. You know what scares more though…this notion of a smart folder. Feel like the godfather - just get the job done, I don't care how you handle it, I don't want to know...just get it done. What the hell is AirDrop?Mail…just worked. Still in shock that they have a free client for yahoo mail (please no yahoo jokes).mail -> deleting a message takes 5 seconds. Have they heard of async?"Command" key instead of "Control" ok, then what the $%&^! is the control key for then"aliases" == shortcuts I thinkI don't see the file system. And I'm scared. All these things I'm downloading…these .dmg files (bad name) where are they going? Can't seem to delete when they're doneUgh...realized need to buy a mini-to-vga adaptor if I want to use my external monitor ($13 on ebay, $39 in apple store).Windows docking is trickiest for me…this notion of detached windows with a menu bar at the top. I don't like this paradigm, it's confusing. But maybe because I've been using Windows for too long.Evernote, Dropbox desktop clients seem almost identical…few quirks here and there I need to get used to.iTunes is still a bit gross. In a weird way it's actually worse on a Mac if thats possible. This is not the MacBook's fault…this is a software design issue. Overall: UI will take some getting used to. Can't decide if this represents the future and I'm stuck in the past…or this is the past and I've been spoiled by the future (which would be Windows…don't be hating I happen to be very productive in Win7)  So there you go - my 90 minute first impression of the MacBook universe.

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• Weird SSIS Configuration Error

  - by Christopher House

  I ran into an interesting SSIS issue that I thought I'd share in hopes that it may save someone from bruising their head after repeatedly banging it on the desk like I did.  I was trying to setup what I believe is referred to as "indirect configuration" in SSIS.  This is where you store your configuration in some repository like a database or a file, then store the location of that repository in an environment variable and use that to configure the connection to your configuration repository.  In my specific situation, I was using a SQL database.  I had this all working, but for reasons I'll not bore you with, I had to move my SSIS development to a new VM last week.  When I got my new VM, I set about creating a new package.  I finished up development on the package and started setting up configuration.  I created an OLE DB connection that pointed to my configuration table then went through the configuration wizard to have the connection string for this connection set through my environment variable.  I then went through the wizard to set another property through a value stored in the configuration table.  When I got to the point where you select the connection, my connection wasn't in the list: As you can see in the screen capture above, the ConfigurationDb connection isn't in the list of available SQL connections in the configuration wizard.  Strange.  I canceled out of the wizard, went to the properties for ConfigurationDb, tested the connection and it was successful.  I went back to the wizard again and this time ConfigurationDb was there.  I completed the wizard then went to test my package.  Unfortunately the package wouldn't run, I got the following error: Unfortunately, googling for this error code didn't help much as none of the results appears related to package configuration.  I did notice that when I went back through the package configuration and tried to edit a previously saved config entry,  I was getting the following error: I checked the connection string I had stored in my environment variable and noticed that indeed, it did not have a provider name.  I didn't recall having included one on my previous VM, but I figured I'd include it just to see what happened.  That made no difference at all.  After a day and a half of trying to figure out what the problem was, I'm pleased to report that through extensive trial and error, I have resolved the error. As it turns out, the person who setup this new VM for me named the server SQLSERVER2008.  This meant my configuration connection string was: Initial Catalog=SSISConfigDb;Data Source=SQLSERVER2008;Integrated Security=SSPI; Just for the heck of it, I tried changing it to: Initial Catalog=SSISConfigDb;Data Source=(local);Integrated Security=SSPI; That did the trick!  As soon as I restarted BIDS, I was able to run the package with no errors at all.  Crazy.  So, the moral of the story is, don't name your server SQLSERVER2008 if you want SSIS configuration to work when using SQL as your config store.

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• Indentify Codecs & Technical Information About Video Files

  - by DigitalGeekery

  Have you ever wanted to play an audio or video file but didn’t have the proper codec installed? Today we’ll show how to determine codecs, along with a host of other technical details about your media files with MediaInfo. Installation Download and install MediaInfo. You can find the download link at the bottom of the page. Note: When installing MediaInfo there is a recommended software bundle which you can opt out of by selecting Do not install option. Each recommended software choice may be different, like in this example it offers Spyware Terminator. The cool thing though is they use Open Candy which opts you out of the install. Just double check to make sure you’re not installing extra crapware. Using MediaInfo The first time you run MediaInfo it will display the Preferences window. There are various option such as language, output format, and whether or not you want MediaInfo to check for new versions. Click OK. Select a file or folder to analyze by clicking on the File or Folder icons on the left of the application window or by selecting File > Open from the menu. You can also drag and drop a file directly onto the application. MediaInfo will display details of your media file. In Basic view, you’ll see basic information. Notice in the example below the video and audio codecs, along with file size, running time of the media file, and even the application used to create the video file (Writing application).    You can switch to some of the other views by selecting View from the Menu and choosing form the dropdown list.   Sheet View will present the information a bit more clearly. You can see in the example below that the video and audio codec are listing in clearly identified columns. (AVC is often more commonly referred to H.264.)   Tree View is perhaps the most detailed. You can see from the example below the codec used for this AVI file is XviD.   Scrolling down even further you’ll see additional information like video and audio bit rates, frame rate, aspect ratio, and more.   In Basic View (and also in Sheet view) you can click to find a player for your file. In this instance with an MP4 file, it took me to the download page for Quicktime. This is by no means the only media player for this file, but if you are stuck for how to play a media file, this will forward you to a solution that works. You can do the same thing with Video codec. Click Go to the web site of this video codec to find a download.   MediaInfo is a simple but powerful tool that can be used to discover the details of a media file, or just to find a compatible codec. It works with most any video file type and is available for Windows, Mac, and Linux. Some Mac and Linux versions, however, are currently command line only. Download MediaInfo Similar Articles Productive Geek Tips How to Convert Videos to 3GP for Mobile PhonesFix for VLC Skipping and Lagging Playing High-Def Video FilesUsing VLC Player Under VistaUse Your Mac Mini as a Media Server Part 2How to Play .OGM Video Files in Windows Vista TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 2010 World Cup Schedule Boot Snooze – Reboot and then Standby or Hibernate Customize Everything Related to Dates, Times, Currency and Measurement in Windows 7 Google Earth replacement Icon (Icons we like) Build Great Charts in Excel with Chart Advisor tinysong gives a shortened URL for you to post on Twitter (or anywhere)

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• How do you formulate the Domain Model in Domain Driven Design properly (Bounded Contexts, Domains)?

  - by lko

  Say you have a few applications which deal with a few different Core Domains. The examples are made up and it's hard to put a real example with meaningful data together (concisely). In Domain Driven Design (DDD) when you start looking at Bounded Contexts and Domains/Sub Domains, it says that a Bounded Context is a "phase" in a lifecycle. An example of Context here would be within an ecommerce system. Although you could model this as a single system, it would also warrant splitting into separate Contexts. Each of these areas within the application have their own Ubiquitous Language, their own Model, and a way to talk to other Bounded Contexts to obtain the information they need. The Core, Sub, and Generic Domains are the area of expertise and can be numerous in complex applications. Say there is a long process dealing with an Entity for example a Book in a core domain. Now looking at the Bounded Contexts there can be a number of phases in the books life-cycle. Say outline, creation, correction, publish, sale phases. Now imagine a second core domain, perhaps a store domain. The publisher has its own branch of stores to sell books. The store can have a number of Bounded Contexts (life-cycle phases) for example a "Stock" or "Inventory" context. In the first domain there is probably a Book database table with basically just an ID to track the different book Entities in the different life-cycles. Now suppose you have 10+ supporting domains e.g. Users, Catalogs, Inventory, .. (hard to think of relevant examples). For example a DomainModel for the Book Outline phase, the Creation phase, Correction phase, Publish phase, Sale phase. Then for the Store core domain it probably has a number of life-cycle phases. public class BookId : Entity { public long Id { get; set; } } In the creation phase (Bounded Context) the book could be a simple class. public class Book : BookId { public string Title { get; set; } public List<string> Chapters { get; set; } //... } Whereas in the publish phase (Bounded Context) it would have all the text, release date etc. public class Book : BookId { public DateTime ReleaseDate { get; set; } //... } The immediate benefit I can see in separating by "life-cycle phase" is that it's a great way to separate business logic so there aren't mammoth all-encompassing Entities nor Domain Services. A problem I have is figuring out how to concretely define the rules to the physical layout of the Domain Model. A. Does the Domain Model get "modeled" so there are as many bounded contexts (separate projects etc.) as there are life-cycle phases across the core domains in a complex application? Edit: Answer to A. Yes, according to the answer by Alexey Zimarev there should be an entire "Domain" for each bounded context. B. Is the Domain Model typically arranged by Bounded Contexts (or Domains, or both)? Edit: Answer to B. Each Bounded Context should have its own complete "Domain" (Service/Entities/VO's/Repositories) C. Does it mean there can easily be 10's of "segregated" Domain Models and multiple projects can use it (the Entities/Value Objects)? Edit: Answer to C. There is a complete "Domain" for each Bounded Context and the Domain Model (Entity/VO layer/project) isn't "used" by the other Bounded Contexts directly, only via chosen paths (i.e. via Domain Events). The part that I am trying to figure out is how the Domain Model is actually implemented once you start to figure out your Bounded Contexts and Core/Sub Domains, particularly in complex applications. The goal is to establish the definitions which can help to separate Entities between the Bounded Contexts and Domains.

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• Passed: Exam 70-480: Programming in HTML5 with JavaScript and CSS3

  First off: Mission accomplished successfully. And it was fun! Using the resources listed in my previous article about Learning Content, I'd like to thank Microsoft Technical Evangelists Jeremy Foster and Michael Palermo for their excellent jump start videos on Channel 9, and the various authors at Pluralsight. Local Prometric testing centre Back in November I chose a local testing centre which was the easiest to access from my office despite the horrible traffic you might experience here on the island. Actually, it was not the closest one. But due to their website, their awards as Microsoft Learning Center, and my general curiosity about the premises, I gave FRCI my priority. Boy, how should I regret this decision this morning... The official Prometric exam guide asks any attendee to show up at least 30 minutes prior to the scheduled time of the test. Well, this should have been the easier part but unfortunately due to heavier traffic than usual I arrived only 20 minutes before time. Not too bad but more to come. The building called 'le Hub' is nicely renovated and provides the right environment for an IT group of companies like FRCI. I think they have currently 5 independent IT departments over there. Even the handling at the reception was straight forward, welcoming and at my ease. But then... first shock: "We don't have any exam registration for today." - Hm, that's nice... Here's my mail confirmation from Prometric. First attack successfully handled and the lady went off again to check their records. Next shock: A couple of minutes later, another guy tries to explain me that "the staff of the testing centre is already on vacation and the centre is officially closed." - Are you kidding me? Here's the official confirmation by Prometric, and I don't find it funny that I take a day off today only to hear this kind of blubbering nonsense. I thought that I'll be on the safe side choosing a company with a good reputation here on the island. Another 40 (!) minutes later, they finally come back to the waiting area with a pre-filled form about the test appointment. And finally, after an hour of waiting, discussing, restarting the testing PC, and lots of talk, I am allowed to sit down and take the exam. Exam details Well, you know the rules. Signing an NDA doesn't allow me to provide you any details about the questions or topics that have been covered. Please check out the official exam description, and you're on the right way. Sorry, guys... ;-) The result "Congratulations! You have passed this Microsoft Certification exam." - In general, I have to admit that the parts on HTML5 and CSS3 were the easiest after all, and that I have to get myself a little bit more familiar with certain Javascript features like class definitions, inheritance and data security. Anyway, exam passed - who cares about the details? Next goal Of course, the journey to Microsoft Certifications continues and my next goal is to pass exams 70-481 - Essentials of Developing Windows Store Apps using HTML5 and JavaScript and 70-482 - Advanced Windows Store App Development using HTML5 and JavaScript. This would allow me to achieve the certification of MCSD: Windows Store Apps using HTML5. I guess, during 2013 I'll be busy with various learning and teaching lessons.

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• How to get this wavefront .obj data onto the frustum?

  - by NoobScratcher

  I've finally figured out how to get the data from a .obj file and store the vertex positions x,y,z into a structure called Points with members x y z which are of type float. I want to know how to get this data onto the screen. Here is my attempt at doing so: //make a fileobject and store list and the index of that list in a c string ifstream file (list[index].c_str() ); std::vector<int>faces; std::vector<Point>points; points.push_back(Point()); Point p; int face[4]; while ( !file.eof() ) { char modelbuffer[10000]; //Get lines and store it in line string file.getline(modelbuffer, 10000); switch(modelbuffer[0]) { case 'v' : sscanf(modelbuffer, "v %f %f %f", &p.x, &p.y, &p.z); points.push_back(p); cout << "Getting Vertex Positions" << endl; cout << "v" << p.x << endl; cout << "v" << p.y << endl; cout << "v" << p.z << endl; break; case 'f': sscanf(modelbuffer, "f %d %d %d %d", face, face+1, face+2, face+3 ); cout << face[0] << endl; cout << face[1] << endl; cout << face[2] << endl; cout << face[3] << endl; faces.push_back(face[0]); faces.push_back(face[1]); faces.push_back(face[2]); faces.push_back(face[3]); } GLuint vertexbuffer; glGenBuffers(1, &vertexbuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glBufferData(GL_ARRAY_BUFFER, points.size(), points.data(), GL_STATIC_DRAW); //glBufferData(GL_ARRAY_BUFFER,sizeof(points), &(points[0]), GL_STATIC_DRAW); glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0); glVertexPointer(3, GL_FLOAT, sizeof(points),points.data()); glIndexPointer(GL_DOUBLE, 0, faces.data()); glDrawArrays(GL_QUADS, 0, points.size()); glDrawElements(GL_QUADS, faces.size(), GL_UNSIGNED_INT, faces.data()); } As you can see I've clearly failed the end part but I really don't know why its not rendering the data onto the frustum? Does anyone have a solution for this?

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• How can I best implement 'cache until further notice' with memcache in multiple tiers?

  - by ajreal

  the term "client" used here is not referring to client's browser, but client server Before cache workflow 1. client make a HTTP request --> 2. server process --> 3. store parsed results into memcache for next use (cache indefinitely) --> 4. return results to client --> 5. client get the result, store into client's local memcache with TTL After cache workflow 1. another client make a HTTP request --> 2. memcache found return memcache results to client --> 3. client get the result, store into client's local memcache with TTL TTL = time to live Is possible for me to know when the data was updated, and to expire relevant memcache(s) accordingly. However, the pitfalls on client site cache TTL Any data update before the TTL is not pick-up by client memcache. In reverse manner, where there is no update, client memcache still expire after the TTL First request (or concurrent requests) after cache TTL will get throttle as it need to repeat the "Before cache workflow" In the event where client require several HTTP requests on a single web page, it could be very bad in performance. Ideal solution should be client to cache indefinitely until further notice. Here are the three proposals about futher notice Proposal 1 : Make use on HTTP header (current implementation) 1. client sent HTTP request last modified time header 2. server check if last data modified time=last cache time return status 304 3. client based on header to decide further processing GOOD? ---- - save some parsing for client - lesser data transfer BAD? ---- - fire a HTTP request is still slow - server end still need to process lots of requests Proposal 2 : Consistently issue a HTTP request to check all data group last modified time 1. client fire a HTTP request 2. server to return last modified time for all data group 3. client compare local last cache time with the result 4. if data group last cache time < server last modified time then request again for that data group only GOOD? ---- - only fetch what is no up-to-date - less requests for server BAD? ---- - every web page require a HTTP request Proposal 3 : Tell client when new data is available (Push) 1. when server end notice there is a change on a data group 2. notify clients on the changes 3. help clients to fetch again data 4. then reset client local memcache after data is parsed GOOD? ---- - let the cache act/behave like a true cache BAD? ---- - encourage race condition My preference is on proposal 3, and something like Gearman could be ideal Where there is a change, Gearman server to sent the task to multiple clients (workers). Am I crazy? (I know my first question is a bit crazy)

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• Optimal Data Structure for our own API

  - by vermiculus

  I'm in the early stages of writing an Emacs major mode for the Stack Exchange network; if you use Emacs regularly, this will benefit you in the end. In order to minimize the number of calls made to Stack Exchange's API (capped at 10000 per IP per day) and to just be a generally responsible citizen, I want to cache the information I receive from the network and store it in memory, waiting to be accessed again. I'm really stuck as to what data structure to store this information in. Obviously, it is going to be a list. However, as with any data structure, the choice must be determined by what data is being stored and what how it will be accessed. What, I would like to be able to store all of this information in a single symbol such as stack-api/cache. So, without further ado, stack-api/cache is a list of conses keyed by last update: `(<csite> <csite> <csite>) where <csite> would be (1362501715 . <site>) At this point, all we've done is define a simple association list. Of course, we must go deeper. Each <site> is a list of the API parameter (unique) followed by a list questions: `("codereview" <cquestion> <cquestion> <cquestion>) Each <cquestion> is, you guessed it, a cons of questions with their last update time: `(1362501715 <question>) (1362501720 . <question>) <question> is a cons of a question structure and a list of answers (again, consed with their last update time): `(<question-structure> <canswer> <canswer> <canswer> and ` `(1362501715 . <answer-structure>) This data structure is likely most accurately described as a tree, but I don't know if there's a better way to do this considering the language, Emacs Lisp (which isn't all that different from the Lisp you know and love at all). The explicit conses are likely unnecessary, but it helps my brain wrap around it better. I'm pretty sure a <csite>, for example, would just turn into (<epoch-time> <api-param> <cquestion> <cquestion> ...) Concerns: Does storing data in a potentially huge structure like this have any performance trade-offs for the system? I would like to avoid storing extraneous data, but I've done what I could and I don't think the dataset is that large in the first place (for normal use) since it's all just human-readable text in reasonable proportion. (I'm planning on culling old data using the times at the head of the list; each inherits its last-update time from its children and so-on down the tree. To what extent this cull should take place: I'm not sure.) Does storing data like this have any performance trade-offs for that which must use it? That is, will set and retrieve operations suffer from the size of the list? Do you have any other suggestions as to what a better structure might look like?

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• SQL to select random mix of rows fairly [migrated]

  - by Matt Sieker

  Here's my problem: I have a set of tables in a database populated with data from a client that contains product information. In addition to the basic product information, there is also information about the manufacturer, and categories for those products (a product can be in one or more categories). These categories are then referred to as "Product Categories", and which stores these products are available at. These tables are updated once a week from a feed from the customer. Since for our purposes, some of the product categories are the same, or closely related for our purposes, there is another level of categories called "General Categories", a general category can have one or more product categories. For the scope of these tables, here's some rough numbers: Data Tables: Products: 475,000 Manufacturers: 1300 Stores: 150 General Categories: 245 Product Categories: 500 Mapping Tables: Product Category -> Product: 655,000 Stores -> Products: 50,000,000 Now, for the actual problem: As part of our software, we need to select n random products, given a store and a general category. However, we also need to ensure a good mix of manufacturers, as in some categories, a single manufacturer dominates the results, and selecting rows at random causes the results to strongly favor that manufacturer. The solution that is currently in place, works for most cases, involves selecting all of the rows that match the store and category criteria, partition them on manufacturer, and include their row number from within their partition, then select from that where the row number for that manufacturer is less than n, and use ROWCOUNT to clamp the total rows returned to n. This query looks something like this: SET ROWCOUNT 6 select p.Id, GeneralCategory_Id, Product_Id, ISNULL(m.DisplayName, m.Name) AS Vendor, MSRP, MemberPrice, FamilyImageName from (select p.Id, gc.Id GeneralCategory_Id, p.Id Product_Id, ctp.Store_id, Manufacturer_id, ROW_NUMBER() OVER (PARTITION BY Manufacturer_id ORDER BY NEWID()) AS 'VendorOrder', MSRP, MemberPrice, FamilyImageName from GeneralCategory gc inner join GeneralCategoriesToProductCategories gctpc ON gc.Id=gctpc.GeneralCategory_Id inner join ProductCategoryToProduct pctp on gctpc.ProductCategory_Id = pctp.ProductCategory_Id inner join Product p on p.Id = pctp.Product_Id inner join StoreToProduct ctp on p.Id = ctp.Product_id where gc.Id = @GeneralCategory and ctp.Store_id=@StoreId and p.Active=1 and p.MemberPrice >0) p inner join Manufacturer m on m.Id = p.Manufacturer_id where VendorOrder <=6 order by NEWID() SET ROWCOUNT 0 (I've tried to somewhat format it to make it cleaner, but I don't think it really helps) Running this query with an execution plan shows that for the majority of these tables, it's doing a Clustered Index Seek. There are two operations that take up roughly 90% of the time: Index Seek (Nonclustered) on StoreToProduct: 17%. This table just contains the key of the store, and the key of the product. It seems that NHibernate decided not to make a composite key when making this table, but I'm not concerned about this at this point, as compared to the other seek... Clustered Index Seek on Product: 69%. I really have no clue how I could make this one more performant. On categories without a lot of products, performance is acceptable (<50ms), however larger categories can take a few hundred ms, with the largest category taking 3s (which has about 170k products). It seems I have two ways to go from this point: Somehow optimize the existing query and table indices to lower the query time. As almost every expensive operation is already a clustered index scan, I don't know what could be done there. The inner query could be tuned to not return all of the possible rows for that category, but I am unsure how to do this, and maintain the requirements (random products, with a good mix of manufacturers) Denormalize this data for the purpose of this query when doing the once a week import. However, I am unsure how to do this and maintain the requirements. Does anyone have any input on either of these items?

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• Multitenancy in SQL Azure

  - by cibrax

  If you are building a SaaS application in Windows Azure that relies on SQL Azure, it’s probably that you will need to support multiple tenants at database level. This is short overview of the different approaches you can use for support that scenario, A different database per tenant A new database is created and assigned when a tenant is provisioned. Pros Complete isolation between tenants. All the data for a tenant lives in a database only he can access. Cons It’s not cost effective. SQL Azure databases are not cheap, and the minimum size for a database is 1GB.  You might be paying for storage that you don’t really use. A different connection pool is required per database. Updates must be replicated across all the databases You need multiple backup strategies across all the databases Multiple schemas in a database shared by all the tenants A single database is shared among all the tenants, but every tenant is assigned to a different schema and database user. Pros You only pay for a single database. Data is isolated at database level. If the credentials for one tenant is compromised, the rest of the data for the other tenants is not. Cons You need to replicate all the database objects in every schema, so the number of objects can increase indefinitely. Updates must be replicated across all the schemas. The connection pool for the database must maintain a different connection per tenant (or set of credentials) A different user is required per tenant, which is stored at server level. You have to backup that user independently. Centralizing the database access with store procedures in a database shared by all the tenants A single database is shared among all the tenants, but nobody can read the data directly from the tables. All the data operations are performed through store procedures that centralize the access to the tenant data. The store procedures contain some logic to map the database user to an specific tenant. Pros You only pay for a single database. You only have a set of objects to maintain and backup. Cons There is no real isolation. All the data for the different tenants is shared in the same tables. You can not use traditional ORM like EF code first for consuming the data. A different user is required per tenant, which is stored at server level. You have to backup that user independently. SQL Federations A single database is shared among all the tenants, but a different federation is used per tenant. A federation in few words, it’s a mechanism for horizontal scaling in SQL Azure, which basically uses the idea of logical partitions to distribute data based on certain criteria. Pros You only have a single database with multiple federations. You can use filtering in the connections to pick the right federation, so any ORM could be used to consume the data. Cons There is no real isolation at that database level. The isolation is enforced programmatically with federations.

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