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  • Play a wav file retrieved from a database on the iPhone?

    - by user312917
    I have alot of wav files stored in sqlite3, but when I retrieve one of them, I can't play it. The retrieve code is NSData *soundData = (NSDATA *)sqlite3_column_blob(statement, 0); mPlayer = [[AVAudioPlayer alloc] initWithData:soundData error:&error]; The data is stored as binary and it's there when I search for it using sqlite3.

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  • Why so many ASP.NET programmers play with Ruby on Rails after working hours?

    - by ITmeze
    I saw that on so many blogs. Lots of the people that were dealing with ASP.NET tend to play with Ruby on Rails after working hours. And It is just a matter of last one or two years. Why is it like that? Is it because when ASP.NET MVC showed up people become more open-minded - having joy with programming again they realize that some other folks had that many years ago, and they do not want to miss what they currently have?

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  • How do I rate limit google's crawl of my class C IP block?

    - by Zak
    I have several sites in a class C network that all get crawled by google on a pretty regular basis. Normally this is fine. However, when google starts crawling all the sites at the same time, the small set of servers that back this IP block can take a pretty big hit on load. With google webmaster tools, you can rate limit the googlebot on a given domain, but I haven't found a way to limit the bot across an IP network yet. Anyone have experience with this? How did you fix it?

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  • WebCenter Innovation Award Winners

    - by Michael Snow
    Of course, here on our WebCenter blog – we’d like to highlight and brag about our great WebCenter winners. The 2012 WebCenter Innovation Award Winners University of Louisville Location: Louisville, KY, USA Industry: Higher Education Fusion Middleware Products: WebCenter Portal, WebCenter Content, JDeveloper, WebLogic, Oracle BI, Oracle IdM University of Louisville is a state supported research university Statewide Informatics Network to improve public health The University of Louisville has implemented WebCenter as part of the LOUI (Louisville Informatics Institute) Initiative, a Statewide Informatics Network, which will improve public healthcare and lower cost through the use of novel technology and next generation analytics, decision support and innovative outcomes-based payment systems. ---------- News Limited Country/Region: Australia Industry: News/Media FMW Products: WebCenter Sites Single platform running websites for 50% of Australia's newspapers News Corp is running half of Australia's newspaper websites on this shared platform powered by Oracle WebCenter Sites and have overtaken their nearest competitors and are now leading in terms of monthly page impressions. At peak they have over 250 editors on the system publishing in real-time.Sites include: www.newsspace.com.au, www.news.com.au, www.theaustralian.com.au and many others ------ Life Technologies Corp. Country/Region: Carlsbad, CA, USAIndustry: Life SciencesFMW Products: WebCenter Portal, SOA Suite Life Technologies Corp. is a global biotechnology tools company dedicated to improving the human condition with innovative life science products. They were awarded an innovation award for their solution utilizing WebCenter Portal for remotely monitoring & repairing biotech instruments. They deployed WebCenter as a portal that accesses Life Technologies cloud based service monitoring system where all customer deployed instruments can be remotely monitored and proactively repaired.  The portal provides alerts from these cloud based monitoring services directly to the customer and to Life Technologies Field Engineers.  The Portal provides insight into the instruments and services customers purchased for the purpose of analyzing and anticipating future customer needs and creating targeted sales and service programs. ----- China Mobile Jiangsu China Mobile Jiangsu is one of the biggest subsidiaries of China Mobile. It has over 25,000 employees and 40 million mobile subscribers. Country/Region: Jiangsu, China Industry: Telecommunications FMW Products: WebCenter Portal, WebCenter Content, JDeveloper, SOA Suite, IdM They were awarded an Innovation Award for their new employee platform powered by WebCenter Portal is designed to serve their 25,000+ employees and help them drive collaboration & productivity. JSMCC (Chian Mobile Jiangsu) Employee Enterprise Portal and Collaboration Platform. It is one of the China Mobile’s most important IT innovation projects. The new platform is designed to serve for JSMCC’s 25000+ employees and to help them improve the working efficiency, changing their traditional working mode to social ways, encouraging employees on business collaboration and innovation. The solution is built on top of Oracle WebCenter Portal Framework and WebCenter Spaces while also leveraging Weblogic Server, UCM, OID, OAM, SES, IRM and Oracle Database 11g. By providing rich collaboration services, knowledge management services, sensitive document protection services, unified user identity management services, unified information search services and personalized information integration capabilities, the working efficiency of JSMCC employees has been greatly improved. Main Functionality : Information portal, office automation integration, personal space, group space, team collaboration with web2.0 services, unified search engine for multiple data sources, document management and protection. SSO for multiple platforms. -------- LADWP – Los Angeles Department for Water and Power Los Angeles Department of Water and Power (LADWP) is the largest public utility company in United States with over 1.6 Million customers. LADWP provides water and power for millions of residential & commercial customers in Southern California. LADWP also bills most of these customers for sanitation services provided by another city department. Country/Region: US – Los Angeles, CA Industry: Public Utility FMW Products: WebCenter Portal, WebCenter Content, JDeveloper, SOA Suite, IdM The new infrastructure consists of: Oracle WebCenter Portal including mobile portal Oracle WebCenter Content for Content Management and Digital Asset Management (DAM) Oracle OAM (IDM, OVD, OAM) integrated with AD for enterprise identity management Oracle Siebel for CRM Oracle DB Oracle SOA Suite for integration of various subsystems and back end systems  The new portal's features include: Complete Graphical redesign based on best practices in UI Design for high usability Customer Self Service implemented through MyAccount (Bill Pay, Payment History, Bill History, Usage Analysis, Service Request Management) Financial Assistance Programs (CRM, WebCenter) Customer Rebate Programs (CRM, WebCenter) Turn On/Off/Transfer of services (Commercial & Residential) Outage Reporting eNotification (SMS, email) Multilingual (English & Spanish) – using WebCenter multi-language support Section 508 (ADA) Compliant Search – Using WebCenter SES (Secured Enterprise Search) Distributed Authorship in WebCenter Content Mobile Access (any Mobile Browser)

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  • Fan running continously on HP Pavillion G6 notebook with 12.04.1 LTS, help please?

    - by Ankit
    Fan is running continously on my HP Pavillion G6 notebook with 12.04.1 LTS. My system specifications are:- Ram: 6Gb Graphics Card:- 1 GB (AMD Raedon 64XX). HDD: 540 GB. Please find a list of ACPI errors logs from dmesg as follows:- buffer@ankit:~$ dmesg | grep ACPI -i [ 0.000000] BIOS-e820: 000000009cebf000 - 000000009cfbf000 (ACPI NVS) [ 0.000000] BIOS-e820: 000000009cfbf000 - 000000009cfff000 (ACPI data) [ 0.000000] ACPI: RSDP 00000000000fe020 00024 (v02 HPQOEM) [ 0.000000] ACPI: XSDT 000000009cffe120 00084 (v01 HPQOEM SLIC-MPC 00000001 01000013) [ 0.000000] ACPI: FACP 000000009cffc000 000F4 (v04 HPQOEM SLIC-MPC 00000001 MSFT 01000013) [ 0.000000] ACPI: DSDT 000000009cfec000 0C132 (v01 HP 1670 00000000 MSFT 01000013) [ 0.000000] ACPI: FACS 000000009cf6c000 00040 [ 0.000000] ACPI: ASF! 000000009cffd000 000A5 (v32 HP 1670 00000001 MSFT 01000013) [ 0.000000] ACPI: HPET 000000009cffb000 00038 (v01 HP 1670 00000001 MSFT 01000013) [ 0.000000] ACPI: APIC 000000009cffa000 0008C (v02 HP 1670 00000001 MSFT 01000013) [ 0.000000] ACPI: MCFG 000000009cff9000 0003C (v01 HP 1670 00000001 MSFT 01000013) [ 0.000000] ACPI: SLIC 000000009cfeb000 00176 (v01 HPQOEM SLIC-MPC 00000001 MSFT 01000013) [ 0.000000] ACPI: SSDT 000000009cfea000 00D52 (v01 HP 1670 00001000 MSFT 01000013) [ 0.000000] ACPI: BOOT 000000009cfe8000 00028 (v01 HP 1670 00000001 MSFT 01000013) [ 0.000000] ACPI: ASPT 000000009cfe5000 00034 (v07 HP 1670 00000001 MSFT 01000013) [ 0.000000] ACPI: SSDT 000000009cfe4000 00780 (v01 HP 1670 00003000 INTL 20100121) [ 0.000000] ACPI: SSDT 000000009cfe3000 00996 (v01 HP 1670 00003000 INTL 20100121) [ 0.000000] ACPI: SSDT 000000009cfdd000 0219F (v01 HP 1670 00001000 INTL 20100121) [ 0.000000] ACPI: Local APIC address 0xfee00000 [ 0.000000] ACPI: PM-Timer IO Port: 0x408 [ 0.000000] ACPI: Local APIC address 0xfee00000 [ 0.000000] ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled) [ 0.000000] ACPI: LAPIC (acpi_id[0x02] lapic_id[0x01] enabled) [ 0.000000] ACPI: LAPIC (acpi_id[0x03] lapic_id[0x02] enabled) [ 0.000000] ACPI: LAPIC (acpi_id[0x04] lapic_id[0x03] enabled) [ 0.000000] ACPI: LAPIC (acpi_id[0x05] lapic_id[0x00] disabled) [ 0.000000] ACPI: LAPIC (acpi_id[0x06] lapic_id[0x00] disabled) [ 0.000000] ACPI: LAPIC (acpi_id[0x07] lapic_id[0x00] disabled) [ 0.000000] ACPI: LAPIC (acpi_id[0x08] lapic_id[0x00] disabled) [ 0.000000] ACPI: IOAPIC (id[0x00] address[0xfec00000] gsi_base[0]) [ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl) [ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level) [ 0.000000] ACPI: IRQ0 used by override. [ 0.000000] ACPI: IRQ2 used by override. [ 0.000000] ACPI: IRQ9 used by override. [ 0.000000] Using ACPI (MADT) for SMP configuration information [ 0.000000] ACPI: HPET id: 0x8086a201 base: 0xfed00000 [ 0.005902] ACPI: Core revision 20110623 [ 0.536006] PM: Registering ACPI NVS region at 9cebf000 (1048576 bytes) [ 0.538423] ACPI FADT declares the system doesn't support PCIe ASPM, so disable it [ 0.538429] ACPI: bus type pci registered [ 0.656088] ACPI: Added _OSI(Module Device) [ 0.656094] ACPI: Added _OSI(Processor Device) [ 0.656098] ACPI: Added _OSI(3.0 _SCP Extensions) [ 0.656103] ACPI: Added _OSI(Processor Aggregator Device) [ 0.660335] ACPI: EC: Look up EC in DSDT [ 0.664416] ACPI: Executed 1 blocks of module-level executable AML code [ 0.728303] [Firmware Bug]: ACPI: BIOS _OSI(Linux) query ignored [ 0.729536] ACPI: SSDT 000000009ce70798 00727 (v01 PmRef Cpu0Cst 00003001 INTL 20100121) [ 0.730622] ACPI: Dynamic OEM Table Load: [ 0.730630] ACPI: SSDT (null) 00727 (v01 PmRef Cpu0Cst 00003001 INTL 20100121) [ 0.760829] ACPI: SSDT 000000009ce71a98 00303 (v01 PmRef ApIst 00003000 INTL 20100121) [ 0.761992] ACPI: Dynamic OEM Table Load: [ 0.761998] ACPI: SSDT (null) 00303 (v01 PmRef ApIst 00003000 INTL 20100121) [ 0.792451] ACPI: SSDT 000000009ce6fd98 00119 (v01 PmRef ApCst 00003000 INTL 20100121) [ 0.793521] ACPI: Dynamic OEM Table Load: [ 0.793528] ACPI: SSDT (null) 00119 (v01 PmRef ApCst 00003000 INTL 20100121) [ 0.872981] ACPI: Interpreter enabled [ 0.872992] ACPI: (supports S0 S3 S4 S5) [ 0.873064] ACPI: Using IOAPIC for interrupt routing [ 0.882723] ACPI: EC: GPE = 0x16, I/O: command/status = 0x66, data = 0x62 [ 0.883072] ACPI: No dock devices found. [ 0.883084] PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug [ 0.883882] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-fe]) [ 0.924187] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT] [ 0.924509] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0.RP01._PRT] [ 0.924581] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0.RP02._PRT] [ 0.924659] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0.RP03._PRT] [ 0.924758] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0.PEG0._PRT] [ 0.924973] pci0000:00: Requesting ACPI _OSC control (0x1d) [ 0.925064] pci0000:00: ACPI _OSC request failed (AE_ERROR), returned control mask: 0x1d [ 0.925069] ACPI _OSC control for PCIe not granted, disabling ASPM [ 0.930212] ACPI: PCI Interrupt Link [LNKA] (IRQs 1 3 4 5 6 10 *11 12 14 15) [ 0.930327] ACPI: PCI Interrupt Link [LNKB] (IRQs 1 3 4 5 6 10 *11 12 14 15) [ 0.930436] ACPI: PCI Interrupt Link [LNKC] (IRQs 1 3 4 5 6 10 *11 12 14 15) [ 0.930547] ACPI: PCI Interrupt Link [LNKD] (IRQs 1 3 4 5 6 *10 11 12 14 15) [ 0.930655] ACPI: PCI Interrupt Link [LNKE] (IRQs 1 3 4 5 6 10 11 12 14 15) *0, disabled. [ 0.930764] ACPI: PCI Interrupt Link [LNKF] (IRQs 1 3 4 5 6 10 11 12 14 15) *0, disabled. [ 0.930873] ACPI: PCI Interrupt Link [LNKG] (IRQs 1 3 4 5 6 10 *11 12 14 15) [ 0.930979] ACPI: PCI Interrupt Link [LNKH] (IRQs 1 3 4 5 6 10 11 12 14 15) *0, disabled. [ 0.932142] PCI: Using ACPI for IRQ routing [ 0.967119] pnp: PnP ACPI init [ 0.967151] ACPI: bus type pnp registered [ 0.968356] pnp 00:00: Plug and Play ACPI device, IDs PNP0a08 PNP0a03 (active) [ 0.968516] pnp 00:01: Plug and Play ACPI device, IDs PNP0200 (active) [ 0.968586] pnp 00:02: Plug and Play ACPI device, IDs INT0800 (active) [ 0.968818] pnp 00:03: Plug and Play ACPI device, IDs PNP0103 (active) [ 0.968915] pnp 00:04: Plug and Play ACPI device, IDs PNP0c04 (active) [ 0.969206] system 00:05: Plug and Play ACPI device, IDs PNP0c02 (active) [ 0.969293] pnp 00:06: Plug and Play ACPI device, IDs PNP0b00 (active) [ 0.969418] pnp 00:07: Plug and Play ACPI device, IDs PNP0303 (active) [ 0.969528] pnp 00:08: Plug and Play ACPI device, IDs SYN1e3f SYN1e00 SYN0002 PNP0f13 (active) [ 0.969969] system 00:09: Plug and Play ACPI device, IDs PNP0c02 (active) [ 0.970574] system 00:0a: Plug and Play ACPI device, IDs PNP0c01 (active) [ 0.970617] pnp: PnP ACPI: found 11 devices [ 0.970622] ACPI: ACPI bus type pnp unregistered [ 1.138064] ACPI: Deprecated procfs I/F for AC is loaded, please retry with CONFIG_ACPI_PROCFS_POWER cleared [ 1.138331] ACPI: AC Adapter [ACAD] (off-line) [ 1.139068] ACPI: Lid Switch [LID0] [ 1.139176] ACPI: Power Button [PWRB] [ 1.139286] ACPI: Power Button [PWRF] [ 1.144637] ACPI: Thermal Zone [TZ01] (0 C) [ 1.144677] ACPI: Deprecated procfs I/F for battery is loaded, please retry with CONFIG_ACPI_PROCFS_POWER cleared [ 1.144693] ACPI: Battery Slot [BAT0] (battery present) [ 1.206926] ACPI: Battery Slot [BAT0] (battery present) [ 13.176993] acpi device:1a: registered as cooling_device4 [ 13.179931] acpi device:1b: registered as cooling_device5 [ 13.180221] ACPI: Video Device [VGA] (multi-head: yes rom: no post: no) [ 13.219589] acpi device:20: registered as cooling_device6 [ 13.220851] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no) [ 1649.915134] i8042 aux 00:08: wake-up capability disabled by ACPI [ 1649.915147] i8042 kbd 00:07: wake-up capability enabled by ACPI [ 1650.931028] r8169 0000:03:00.0: wake-up capability enabled by ACPI [ 1650.954743] ehci_hcd 0000:00:1d.0: wake-up capability enabled by ACPI [ 1650.978733] ehci_hcd 0000:00:1a.0: wake-up capability enabled by ACPI [ 1651.010950] ACPI: Preparing to enter system sleep state S3 [ 1652.251505] ACPI: Low-level resume complete [ 1652.360953] ACPI: Waking up from system sleep state S3 [ 1652.427581] ehci_hcd 0000:00:1a.0: wake-up capability disabled by ACPI [ 1652.435579] ehci_hcd 0000:00:1d.0: wake-up capability disabled by ACPI [ 1652.437887] r8169 0000:03:00.0: wake-up capability disabled by ACPI [ 1652.506660] i8042 kbd 00:07: wake-up capability disabled by ACPI [ 1661.238234] ACPI Error: No handler for Region [CMS0] (ffff8801d5035558) [SystemCMOS] (20110623/evregion-373) [ 1661.238253] ACPI Error: Region SystemCMOS (ID=5) has no handler (20110623/exfldio-292) [ 1661.238268] ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPCB.EC0_._Q33] (Node ffff8801d5054de8), AE_NOT_EXIST (20110623/psparse-536) [ 3151.784288] i8042 aux 00:08: wake-up capability disabled by ACPI [ 3151.784301] i8042 kbd 00:07: wake-up capability enabled by ACPI [ 3152.797676] r8169 0000:03:00.0: wake-up capability enabled by ACPI [ 3152.821379] ehci_hcd 0000:00:1d.0: wake-up capability enabled by ACPI [ 3152.845367] ehci_hcd 0000:00:1a.0: wake-up capability enabled by ACPI [ 3152.877600] ACPI: Preparing to enter system sleep state S3 [ 3154.313213] ACPI: Low-level resume complete [ 3154.422297] ACPI: Waking up from system sleep state S3 [ 3154.489692] ehci_hcd 0000:00:1a.0: wake-up capability disabled by ACPI [ 3154.497667] ehci_hcd 0000:00:1d.0: wake-up capability disabled by ACPI [ 3154.505947] r8169 0000:03:00.0: wake-up capability disabled by ACPI [ 3154.568985] i8042 kbd 00:07: wake-up capability disabled by ACPI [ 3162.745149] ACPI Error: No handler for Region [CMS0] (ffff8801d5035558) [SystemCMOS] (20110623/evregion-373) [ 3162.745168] ACPI Error: Region SystemCMOS (ID=5) has no handler (20110623/exfldio-292) [ 3162.745183] ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPCB.EC0_._Q33] (Node ffff8801d5054de8), AE_NOT_EXIST (20110623/psparse-536) [ 6775.723501] ACPI Error: No handler for Region [CMS0] (ffff8801d5035558) [SystemCMOS] (20110623/evregion-373) [ 6775.723519] ACPI Error: Region SystemCMOS (ID=5) has no handler (20110623/exfldio-292) [ 6775.723535] ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPCB.EC0_._Q33] (Node ffff8801d5054de8), AE_NOT_EXIST (20110623/psparse-536) [10388.004760] ACPI Error: No handler for Region [CMS0] (ffff8801d5035558) [SystemCMOS] (20110623/evregion-373) [10388.004778] ACPI Error: Region SystemCMOS (ID=5) has no handler (20110623/exfldio-292) [10388.004801] ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPCB.EC0_._Q33] (Node ffff8801d5054de8), AE_NOT_EXIST (20110623/psparse-536) [10723.591930] i8042 aux 00:08: wake-up capability disabled by ACPI [10723.591942] i8042 kbd 00:07: wake-up capability enabled by ACPI [10724.607624] r8169 0000:03:00.0: wake-up capability enabled by ACPI [10724.631349] ehci_hcd 0000:00:1d.0: wake-up capability enabled by ACPI [10724.655339] ehci_hcd 0000:00:1a.0: wake-up capability enabled by ACPI [10724.687572] ACPI: Preparing to enter system sleep state S3 [10726.123176] ACPI: Low-level resume complete [10726.232181] ACPI: Waking up from system sleep state S3 [10726.303653] ehci_hcd 0000:00:1a.0: wake-up capability disabled by ACPI [10726.311648] ehci_hcd 0000:00:1d.0: wake-up capability disabled by ACPI [10726.315734] r8169 0000:03:00.0: wake-up capability disabled by ACPI [10726.379287] i8042 kbd 00:07: wake-up capability disabled by ACPI [10734.393523] ACPI Error: No handler for Region [CMS0] (ffff8801d5035558) [SystemCMOS] (20110623/evregion-373) [10734.393542] ACPI Error: Region SystemCMOS (ID=5) has no handler (20110623/exfldio-292) [10734.393557] ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPCB.EC0_._Q33] (Node ffff8801d5054de8), AE_NOT_EXIST (20110623/ps Continuous sound from the fan is very annoying, any help would highly appreciated.

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  • Scaling-out Your Services by Message Bus based WCF Transport Extension &ndash; Part 1 &ndash; Background

    - by Shaun
    Cloud computing gives us more flexibility on the computing resource, we can provision and deploy an application or service with multiple instances over multiple machines. With the increment of the service instances, how to balance the incoming message and workload would become a new challenge. Currently there are two approaches we can use to pass the incoming messages to the service instances, I would like call them dispatcher mode and pulling mode.   Dispatcher Mode The dispatcher mode introduces a role which takes the responsible to find the best service instance to process the request. The image below describes the sharp of this mode. There are four clients communicate with the service through the underlying transportation. For example, if we are using HTTP the clients might be connecting to the same service URL. On the server side there’s a dispatcher listening on this URL and try to retrieve all messages. When a message came in, the dispatcher will find a proper service instance to process it. There are three mechanism to find the instance: Round-robin: Dispatcher will always send the message to the next instance. For example, if the dispatcher sent the message to instance 2, then the next message will be sent to instance 3, regardless if instance 3 is busy or not at that moment. Random: Dispatcher will find a service instance randomly, and same as the round-robin mode it regardless if the instance is busy or not. Sticky: Dispatcher will send all related messages to the same service instance. This approach always being used if the service methods are state-ful or session-ful. But as you can see, all of these approaches are not really load balanced. The clients will send messages at any time, and each message might take different process duration on the server side. This means in some cases, some of the service instances are very busy while others are almost idle. For example, if we were using round-robin mode, it could be happened that most of the simple task messages were passed to instance 1 while the complex ones were sent to instance 3, even though instance 1 should be idle. This brings some problem in our architecture. The first one is that, the response to the clients might be longer than it should be. As it’s shown in the figure above, message 6 and 9 can be processed by instance 1 or instance 2, but in reality they were dispatched to the busy instance 3 since the dispatcher and round-robin mode. Secondly, if there are many requests came from the clients in a very short period, service instances might be filled by tons of pending tasks and some instances might be crashed. Third, if we are using some cloud platform to host our service instances, for example the Windows Azure, the computing resource is billed by service deployment period instead of the actual CPU usage. This means if any service instance is idle it is wasting our money! Last one, the dispatcher would be the bottleneck of our system since all incoming messages must be routed by the dispatcher. If we are using HTTP or TCP as the transport, the dispatcher would be a network load balance. If we wants more capacity, we have to scale-up, or buy a hardware load balance which is very expensive, as well as scaling-out the service instances. Pulling Mode Pulling mode doesn’t need a dispatcher to route the messages. All service instances are listening to the same transport and try to retrieve the next proper message to process if they are idle. Since there is no dispatcher in pulling mode, it requires some features on the transportation. The transportation must support multiple client connection and server listening. HTTP and TCP doesn’t allow multiple clients are listening on the same address and port, so it cannot be used in pulling mode directly. All messages in the transportation must be FIFO, which means the old message must be received before the new one. Message selection would be a plus on the transportation. This means both service and client can specify some selection criteria and just receive some specified kinds of messages. This feature is not mandatory but would be very useful when implementing the request reply and duplex WCF channel modes. Otherwise we must have a memory dictionary to store the reply messages. I will explain more about this in the following articles. Message bus, or the message queue would be best candidate as the transportation when using the pulling mode. First, it allows multiple application to listen on the same queue, and it’s FIFO. Some of the message bus also support the message selection, such as TIBCO EMS, RabbitMQ. Some others provide in memory dictionary which can store the reply messages, for example the Redis. The principle of pulling mode is to let the service instances self-managed. This means each instance will try to retrieve the next pending incoming message if they finished the current task. This gives us more benefit and can solve the problems we met with in the dispatcher mode. The incoming message will be received to the best instance to process, which means this will be very balanced. And it will not happen that some instances are busy while other are idle, since the idle one will retrieve more tasks to make them busy. Since all instances are try their best to be busy we can use less instances than dispatcher mode, which more cost effective. Since there’s no dispatcher in the system, there is no bottleneck. When we introduced more service instances, in dispatcher mode we have to change something to let the dispatcher know the new instances. But in pulling mode since all service instance are self-managed, there no extra change at all. If there are many incoming messages, since the message bus can queue them in the transportation, service instances would not be crashed. All above are the benefits using the pulling mode, but it will introduce some problem as well. The process tracking and debugging become more difficult. Since the service instances are self-managed, we cannot know which instance will process the message. So we need more information to support debug and track. Real-time response may not be supported. All service instances will process the next message after the current one has done, if we have some real-time request this may not be a good solution. Compare with the Pros and Cons above, the pulling mode would a better solution for the distributed system architecture. Because what we need more is the scalability, cost-effect and the self-management.   WCF and WCF Transport Extensibility Windows Communication Foundation (WCF) is a framework for building service-oriented applications. In the .NET world WCF is the best way to implement the service. In this series I’m going to demonstrate how to implement the pulling mode on top of a message bus by extending the WCF. I don’t want to deep into every related field in WCF but will highlight its transport extensibility. When we implemented an RPC foundation there are many aspects we need to deal with, for example the message encoding, encryption, authentication and message sending and receiving. In WCF, each aspect is represented by a channel. A message will be passed through all necessary channels and finally send to the underlying transportation. And on the other side the message will be received from the transport and though the same channels until the business logic. This mode is called “Channel Stack” in WCF, and the last channel in the channel stack must always be a transport channel, which takes the responsible for sending and receiving the messages. As we are going to implement the WCF over message bus and implement the pulling mode scaling-out solution, we need to create our own transport channel so that the client and service can exchange messages over our bus. Before we deep into the transport channel, let’s have a look on the message exchange patterns that WCF defines. Message exchange pattern (MEP) defines how client and service exchange the messages over the transportation. WCF defines 3 basic MEPs which are datagram, Request-Reply and Duplex. Datagram: Also known as one-way, or fire-forgot mode. The message sent from the client to the service, and no need any reply from the service. The client doesn’t care about the message result at all. Request-Reply: Very common used pattern. The client send the request message to the service and wait until the reply message comes from the service. Duplex: The client sent message to the service, when the service processing the message it can callback to the client. When callback the service would be like a client while the client would be like a service. In WCF, each MEP represent some channels associated. MEP Channels Datagram IInputChannel, IOutputChannel Request-Reply IRequestChannel, IReplyChannel Duplex IDuplexChannel And the channels are created by ChannelListener on the server side, and ChannelFactory on the client side. The ChannelListener and ChannelFactory are created by the TransportBindingElement. The TransportBindingElement is created by the Binding, which can be defined as a new binding or from a custom binding. For more information about the transport channel mode, please refer to the MSDN document. The figure below shows the transport channel objects when using the request-reply MEP. And this is the datagram MEP. And this is the duplex MEP. After investigated the WCF transport architecture, channel mode and MEP, we finally identified what we should do to extend our message bus based transport layer. They are: Binding: (Optional) Defines the channel elements in the channel stack and added our transport binding element at the bottom of the stack. But we can use the build-in CustomBinding as well. TransportBindingElement: Defines which MEP is supported in our transport and create the related ChannelListener and ChannelFactory. This also defines the scheme of the endpoint if using this transport. ChannelListener: Create the server side channel based on the MEP it’s. We can have one ChannelListener to create channels for all supported MEPs, or we can have ChannelListener for each MEP. In this series I will use the second approach. ChannelFactory: Create the client side channel based on the MEP it’s. We can have one ChannelFactory to create channels for all supported MEPs, or we can have ChannelFactory for each MEP. In this series I will use the second approach. Channels: Based on the MEPs we want to support, we need to implement the channels accordingly. For example, if we want our transport support Request-Reply mode we should implement IRequestChannel and IReplyChannel. In this series I will implement all 3 MEPs listed above one by one. Scaffold: In order to make our transport extension works we also need to implement some scaffold stuff. For example we need some classes to send and receive message though out message bus. We also need some codes to read and write the WCF message, etc.. These are not necessary but would be very useful in our example.   Message Bus There is only one thing remained before we can begin to implement our scaling-out support WCF transport, which is the message bus. As I mentioned above, the message bus must have some features to fulfill all the WCF MEPs. In my company we will be using TIBCO EMS, which is an enterprise message bus product. And I have said before we can use any message bus production if it’s satisfied with our requests. Here I would like to introduce an interface to separate the message bus from the WCF. This allows us to implement the bus operations by any kinds bus we are going to use. The interface would be like this. 1: public interface IBus : IDisposable 2: { 3: string SendRequest(string message, bool fromClient, string from, string to = null); 4:  5: void SendReply(string message, bool fromClient, string replyTo); 6:  7: BusMessage Receive(bool fromClient, string replyTo); 8: } There are only three methods for the bus interface. Let me explain one by one. The SendRequest method takes the responsible for sending the request message into the bus. The parameters description are: message: The WCF message content. fromClient: Indicates if this message was came from the client. from: The channel ID that this message was sent from. The channel ID will be generated when any kinds of channel was created, which will be explained in the following articles. to: The channel ID that this message should be received. In Request-Reply and Duplex MEP this is necessary since the reply message must be received by the channel which sent the related request message. The SendReply method takes the responsible for sending the reply message. It’s very similar as the previous one but no “from” parameter. This is because it’s no need to reply a reply message again in any MEPs. The Receive method takes the responsible for waiting for a incoming message, includes the request message and specified reply message. It returned a BusMessage object, which contains some information about the channel information. The code of the BusMessage class is 1: public class BusMessage 2: { 3: public string MessageID { get; private set; } 4: public string From { get; private set; } 5: public string ReplyTo { get; private set; } 6: public string Content { get; private set; } 7:  8: public BusMessage(string messageId, string fromChannelId, string replyToChannelId, string content) 9: { 10: MessageID = messageId; 11: From = fromChannelId; 12: ReplyTo = replyToChannelId; 13: Content = content; 14: } 15: } Now let’s implement a message bus based on the IBus interface. Since I don’t want you to buy and install the TIBCO EMS or any other message bus products, I will implement an in process memory bus. This bus is only for test and sample purpose. It can only be used if the service and client are in the same process. Very straightforward. 1: public class InProcMessageBus : IBus 2: { 3: private readonly ConcurrentDictionary<Guid, InProcMessageEntity> _queue; 4: private readonly object _lock; 5:  6: public InProcMessageBus() 7: { 8: _queue = new ConcurrentDictionary<Guid, InProcMessageEntity>(); 9: _lock = new object(); 10: } 11:  12: public string SendRequest(string message, bool fromClient, string from, string to = null) 13: { 14: var entity = new InProcMessageEntity(message, fromClient, from, to); 15: _queue.TryAdd(entity.ID, entity); 16: return entity.ID.ToString(); 17: } 18:  19: public void SendReply(string message, bool fromClient, string replyTo) 20: { 21: var entity = new InProcMessageEntity(message, fromClient, null, replyTo); 22: _queue.TryAdd(entity.ID, entity); 23: } 24:  25: public BusMessage Receive(bool fromClient, string replyTo) 26: { 27: InProcMessageEntity e = null; 28: while (true) 29: { 30: lock (_lock) 31: { 32: var entity = _queue 33: .Where(kvp => kvp.Value.FromClient == fromClient && (kvp.Value.To == replyTo || string.IsNullOrWhiteSpace(kvp.Value.To))) 34: .FirstOrDefault(); 35: if (entity.Key != Guid.Empty && entity.Value != null) 36: { 37: _queue.TryRemove(entity.Key, out e); 38: } 39: } 40: if (e == null) 41: { 42: Thread.Sleep(100); 43: } 44: else 45: { 46: return new BusMessage(e.ID.ToString(), e.From, e.To, e.Content); 47: } 48: } 49: } 50:  51: public void Dispose() 52: { 53: } 54: } The InProcMessageBus stores the messages in the objects of InProcMessageEntity, which can take some extra information beside the WCF message itself. 1: public class InProcMessageEntity 2: { 3: public Guid ID { get; set; } 4: public string Content { get; set; } 5: public bool FromClient { get; set; } 6: public string From { get; set; } 7: public string To { get; set; } 8:  9: public InProcMessageEntity() 10: : this(string.Empty, false, string.Empty, string.Empty) 11: { 12: } 13:  14: public InProcMessageEntity(string content, bool fromClient, string from, string to) 15: { 16: ID = Guid.NewGuid(); 17: Content = content; 18: FromClient = fromClient; 19: From = from; 20: To = to; 21: } 22: }   Summary OK, now I have all necessary stuff ready. The next step would be implementing our WCF message bus transport extension. In this post I described two scaling-out approaches on the service side especially if we are using the cloud platform: dispatcher mode and pulling mode. And I compared the Pros and Cons of them. Then I introduced the WCF channel stack, channel mode and the transport extension part, and identified what we should do to create our own WCF transport extension, to let our WCF services using pulling mode based on a message bus. And finally I provided some classes that need to be used in the future posts that working against an in process memory message bus, for the demonstration purpose only. In the next post I will begin to implement the transport extension step by step.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • GDL Presents: Women Techmakers with Diane Greene

    GDL Presents: Women Techmakers with Diane Greene Megan Smith co-hosts with Cloud Platform PM Lead Jessie Jiang. They will be exploring former VMWare CEO and current Google, Inc. board member Diane Greene's strategic thoughts about Cloud on a high-level, as well as the direction in which she sees the tech industry for women. Hosts: Megan Smith - Vice President, Google [x] | Jessie Jiang - Product Management Lead, Google Cloud Platform Guest: Diane Greene - Board of Directors, Google, Inc. From: GoogleDevelopers Views: 0 0 ratings Time: 01:00:00 More in Science & Technology

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  • YouTube Developers Live: Playlist Party Picker

    YouTube Developers Live: Playlist Party Picker Submit your questions here: goo.gl Danny Hermes, Jeff Posnick and JJ Behrens discuss how they built Party Playlist Picker, a Python App Engine application that lets Google+ users collaboratively edit YouTube Playlists. More details are at apiblog.youtube.com Helpful Links: OAuth2 for GData APIs - googleappsdeveloper.blogspot.com Channel API - developers.google.com Memcache - developers.google.com From: GoogleDevelopers Views: 141 18 ratings Time: 40:14 More in Science & Technology

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  • Apps Script Office Hours - September 6, 2012

    Apps Script Office Hours - September 6, 2012 In this week's episode of Google Apps Script office hours, Ikai and Jan: - Discuss the upcoming Apps Script hackathon in Austin, Texas (goo.gl - Answer a variety of questions from the Google Moderator. - Answer live questions about monetization and other topics. To find out when the next office hours will be held visit: developers.google.com From: GoogleDevelopers Views: 301 10 ratings Time: 25:28 More in Science & Technology

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  • Geo for Good Summit Highlights

    Geo for Good Summit Highlights The last week of September, Google hosted the Geo for Good User Summit, for nonprofit mapping and technology specialists to update the nonprofit community about new and special features of Google's mapping products. In this week's Maps Developers Live event, Mano Marks from Maps Developer Relations and Raleigh Seamster, Program Manager with the Google Earth Outreach team will talk about the highlights of the Summit and show off some great examples of people using Maps to help the world. From: GoogleDevelopers Views: 0 0 ratings Time: 00:00 More in Education

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  • App Scripts Office Hours - August 30, 2012

    App Scripts Office Hours - August 30, 2012 In this week's episode of Google Apps Script office hours, Eric and Ikai: - Highlight a blog post on Google Analytics in Apps Script (goo.gl - Answer questions about Charts Dashboards and other topics. - Discuss the upcoming Apps Script hackathon in Austin, Texas (goo.gl To find out when the next office hours will be held visit: developers.google.com From: GoogleDevelopers Views: 135 16 ratings Time: 33:51 More in Science & Technology

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  • Apps Script Office Hours - August 23, 2012

    Apps Script Office Hours - August 23, 2012 In this week's episode on Google Apps Script office hours, Jan and Ikai: - Cover the release notes (goo.gl - Highlight a blog post on Google Analytics in Apps Script (goo.gl - Discuss the upcoming Apps Script hackathon in Austin, Texas (goo.gl To find out when the next office hours will be held visit: developers.google.com From: GoogleDevelopers Views: 803 16 ratings Time: 25:00 More in Science & Technology

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  • Apps Script Office Hours - November 9, 2012

    Apps Script Office Hours - November 9, 2012 In this episode Ikai and Eric ... - Plugged the upcoming hackathon in Los Angeles. - Covered the release notes from the past week, which included some great enchancements to the Gmail and Drive services. - Discussed the new Google Cloud SQL integration in Apps Script. - Hyped the upcoming special episode with the creator of the "Google Analytics Report Automation (Magic)" script. - Answered questions about integrating Apps Script with Google Docs and Forms. The schedule of future episodes can be found at: developers.google.com From: GoogleDevelopers Views: 61 2 ratings Time: 31:24 More in Science & Technology

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  • "Unsafe JavaScript attempt to access frame with URL..." error when developing for Facebook Open Grap

    - by Neil Sarkar
    Chrome (or any other webkit browser) throws a ton of these "Unsafe JavaScript attempt to access frame with URL..." when working with the Facebook Open Graph API. It doesn't interfere with actual operation, but it does make the javascript console basically unusable. I'd like to know if there is a way to suppress warnings in the console? Or if there are other solutions you guys can think of, I would really appreciate it. Thanks.

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  • Problems with jQuery getJSON using local files in Chrome

    - by Tauren
    I have a very simple test page that uses XHR requests with jQuery's $.getJSON and $.ajax methods. The same page works in some situations and not in others. Specificially, it doesn't work in Chrome on Ubuntu. I'm testing on Ubuntu 9.10 with Chrome 5.0.342.7 beta and Mac OSX 10.6.2 with Chrome 5.0.307.9 beta. It works correctly when files are installed on a web server from both Ubuntu/Chrome and Mac/Chrome (try it out here). It works correctly when files are installed on local hard drive in Mac/Chrome (accessed with file:///...). It FAILS when files are installed on local hard drive in Ubuntu/Chrome (access with file:///...). The small set of 3 files can be downloaded in a tar/gzip file from here: http://issues.tauren.com/testjson/testjson.tgz When it works, the Chrome console will say: XHR finished loading: "http://issues.tauren.com/testjson/data.json". index.html:16Using getJSON index.html:21 Object result: "success" __proto__: Object index.html:22success XHR finished loading: "http://issues.tauren.com/testjson/data.json". index.html:29Using ajax with json dataType index.html:34 Object result: "success" __proto__: Object index.html:35success XHR finished loading: "http://issues.tauren.com/testjson/data.json". index.html:46Using ajax with text dataType index.html:51{"result":"success"} index.html:52undefined When it doesn't work, the Chrome console will show this: index.html:16Using getJSON index.html:21null index.html:22Uncaught TypeError: Cannot read property 'result' of null index.html:29Using ajax with json dataType index.html:34null index.html:35Uncaught TypeError: Cannot read property 'result' of null index.html:46Using ajax with text dataType index.html:51 index.html:52undefined Notice that it doesn't even show the XHR requests, although the success handler is run. I swear this was working previously in Ubuntu/Chrome, and am worried something got messed up. I already uninstalled and reinstalled Chrome, but that didn't help. Can someone try it out locally on your Ubuntu system and tell me if you have any troubles? Note that it seems to be working fine in Firefox.

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  • How to call parent window function in chrome browser?

    - by Pier Luigi
    HI, I've surprisingly found problems, in Chrome browser, in calling window parent javascript functions. If I have a window with a javascript function defined in it <script type="text/javascript"> function dolink() { . . . } </script> and I have an iframe inside that window that makes this call using jquery <script type="text/javascript"> $(function() { $('a.arglink').click(function() { window.parent.dolink($(this).attr('href')); return false; }); }); </script> the call to dolink function doesn't work. Stepping with chrome javascript debugger, it appears that window.parent.dolink is undefined. It's by design or a mistake that I made? In Firefox and IE it works fine.

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