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  • What's the best way to use requestAnimationFrame and fixed frame rates

    - by m90
    I recently got into using the HTML5-requestAnimationFrame-API a lot on animation-heavy websites, especially after seeing the Jank Busters talk. This seems to work pretty well and really improve performance in many cases. Yet one question still persists for me: When wanting to use an animation that is NOT entirely calculated (think spritesheets for example) you will have to aim for a fixed frame rate. Of course one could go back to use setInterval again, but maybe there are other ways to tackle this. The two ways I could think of using requestAnimationFrame with a fixed frame rate are: var fps = 25; //frames per second function animate(){ //actual drawing goes here setTimeout(function(){ requestAnimationFrame(animate); }, 1000 / fps) } animate(); or var fps = 25; //frames per second var lastExecution = new Date().getTime(); function animate(){ var now = new Date().getTime(); if ((now - lastExecution) > (1000 / fps)){ //do actual drawing lastExecution = new Date().getTime(); } requestAnimationFrame(animate); } animate(); Personally, I'd opt for the second option (the first one feels like cheating), yet it seems to be more buggy in certain situations. Is this approach really worth it (especially at low frame rates like 12.5)? Are there things to be improved? Is there another way to tackle this?

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  • Ubuntu 12.04 fresh install wont boot up

    - by user147220
    im running ubuntu 12.04 and it refuses to boot up. the screen will come on for a second, the mosue will appear, then itll go black again all inside about 3 seconds. i let it just do that for a while and eventually a window popped up saying i had a display issue. I didn't have a mouse but there was a button saying "ok" at the bottom that i couldnt click on. i hit enter, got through that screen, now im looking at another that says "What would you like to do?" - run in low-graphics mode for just one session - reconfigure graphics - troubleshoot the error - exit to console login then two buttons, cancel, and ok. I dont have a mouse and its not letting me navigate between these options with tab. firstly, if i make it through these windows will it get me into the computer so i can try and fix whats going on? also, whats going on here? also, how can i click on these buttons without the use of tab or a mouse?

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  • 2 year cis degree and in school for computer science what can I do?

    - by chame1eon
    Hi I am 29 and have a recent 2 cis year degree from a community college , an A+ certification , and meager experience with web stuff ( Java , Javascript , php ) while in my 1 year help desk internship. In all the programming classes I was able to blow through the homework easily even while other students were panicking and dropping. I think I have managed to avoid the most atrocious noob/self taught mistakes ( spaghetti code etc) by just doing research before starting something and trying to keep good design in mind. Even so I'd have to make heavy use of references to crawl through even simple projects that would result in fully finished useful applications. I need a job now and I am tired of the slow pace of the classes and would love to get any kind of practical experience I could. The problem is that I am not sure what I should be trying to do. I have a very strong preference for application programming or at least anything light on design and preferably pretty low level. If I can't do that then anything technology related , for example help desk would be better than nothing. I live near Raleigh NC. Am I qualified for anything that could contribute to coding (C++ or Java ) experience or even web development though I don't really like it. Would web development experience help. If not is there anything I could read or do that could help? Is the help desk my only choice? If it is, are there any relatively quick certifications or anything similar that would help while I am waiting? Sorry about the long multi-part question. Thanks for reading.

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  • Hitching and Slowness Due to HDD Activity on Ubuntu, But Not Windows?

    - by Espionage724
    It's been bothering me for months now, but I've noticed in Ubuntu (or any distro of Linux I've tried), any major I/O activity will cause hitching and general slowness. For example, if I try doing a file transfer from my network computer to the computer I'm using and try moving the mouse after a while, it might not respond for a second or so. Similar incidents occur in other cases too (right-clicking to get a context menu takes a few seconds, hitting the drop-down application bar takes a while, etc). My HDD isn't top-notch (a WD Blue 500GB 7200RPM drive) but I don't recall it being nearly this bad in Windows 7, 8, or 8.1. CPU activity during file transfers is relatively low (less than 10-20% on all cores of a Phenom II X4 @ 3.3Ghz). I'm using Gnome System Monitor (on Xubuntu) and can't seem to see what kind of HDD activity is occurring though. I have 8GB of RAM too, which is moderately being used (2.5GB), but shouldn't be a problem either. Any ideas what's up? I've tried kernels between 3.8 and 3.11 (i'm using saucy currently with 3.11).

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  • How to build a "traffic AI"?

    - by Lunikon
    A project I am working on right now features a lot of "traffic" in the sense of cars moving along roads, aircraft moving aroun an apron etc. As of now the available paths are precalculated, so nodes are generated automatically for crossings which themselves are interconnected by edges. When a character/agent spawns into the world it starts at some node and finds a path to a target node by means of a simply A* algorithm. The agent follows the path and ultimately reaches its destination. No problem so far. Now I need to enable the agents to avoid collisions and to handle complex traffic situations. Since I'm new to the field of AI I looked up several papers/articles on steering behavior but found them to be too low-level. My problem consists less of the actual collision avoidance (which is rather simple in this case because the agents follow strictly defined paths) but of situations like one agent leaving a dead-end while another one wants to enter exactly the same one. Or two agents meeting at a bottleneck which only allows one agent to pass at a time but both need to pass it (according to the optimal route found before) and they need to find a way to let the other one pass first. So basically the main aspect of the problem would be predicting traffic movement to avoid dead-locks. Difficult to describe, but I guess you get what I mean. Do you have any recommendations for me on where to start looking? Any papers, sample projects or similar things that could get me started? I appreciate your help!

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  • How to persuade C fanatics to work on my C++ open source project?

    - by paperjam
    I am launching an open-source project into a space where a lot of the development is still done Linux-kernel-style, i.e. C-language with a low-level mindset. There are multiple benefits to C++ in our space but I fear those used to working in C will be scared off. How can I make the case for the benefits of C++? Specifically, the following C++ attributes are very valuable: concept of objects and reference-counting pointers - really don't want to have to malloc(sizeof(X)) or memcpy() structs templates for specialising whole bodies of code with specific performance optimizations and for avoiding duplication of code. template metaprogramming related to the above syntactic sweetness available (e.g. operator overloading, to be used in very small doses) STL Boost libraries Many of the knee-jerk negative reactions to C++ are illfounded. Performance does not suffer: modern compilers can flatten dozens of call stack levels and avoid bloat through wide use of template specializations. Granted, when using metaprogramming and building multiple specializations of a large call tree, compile time is slower but there are ways to mitigate this. How can I sell C++?

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  • Database Insider - December 2012 issue

    - by Javier Puerta
    The December issue of the Database Insider newsletter is now available. (Full newsletter here) Big Data: From Acquisition to Analysis 2012 will likely be remembered as the year of big data, as a new generation of technologies enables organizations to acquire, organize, and analyze the exponentially growing and typically less-structured data generated from a variety of new sources. Oracle has produced a series of five short videos that offer a quick and compelling high-level introduction to big data. Read More Total Cost of Ownership Comparison: Oracle Exadata vs. IBM P-Series Read the research that found that over three years, the IBM hardware running Oracle Database cost 31 percent more in total cost of ownership than Oracle Exadata. Webcast - Oracle Exadata Database Machine X3 Learn about Oracle’s next-generation database machine, Oracle Exadata X3, that combines massive memory and low-cost disks to deliver the highest performance at the lowest cost. Available in an eight-rack configuration, it allows you to start small and grow.    Maximum Availability with Oracle GoldenGate Discover how to eliminate not only unplanned downtime but also planned downtime resulting from database upgrades, migrations, and consolidation.Thursday, December 1319:00 CET / 6 pm. UK   

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  • How you choose your first job as a programmer? [on hold]

    - by sliter
    For Brief I am a recently graduated CS student. I am looking for a job these days, but I have no idea what kind of software development jobs I like(embedded system,web development or else...). And I am looking for your advice. Here is a little more While I was a student, I had an one year internship experience as a system engineer in a semi-conductor company where I wrote Linux driver, tuned system performance, etc.. I was happy about this experience as it allowed me to deepen my understanding of the operating system and different low level things. And I thought "Em, I will continue in the embedded area after I graduate". At the end of my study, I am doing an another internship in web development, both front-end and back-end. And I also enjoys a lot the process of learning new things and making it work (Backbone, Node, socketio, etc..). Now, when I am looking for a software development position, I do not know what to apply! All I know is that I want a job which allows me to keep up with the trends instead of repeating. But besides this, I've no idea what specific type of job I want to do. Turn back to embedded system? Continue with web development? Change to other promising areas(data mining)? All these development positions makes no big difference to me. But I think this is not good and I need some criteria at choosing. So I am looking for advice and I would really appreciate if you can share your experience.

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  • Ubuntu 13.04 Sound Problem after following weird commands

    - by user206356
    After launching a few commands : echo autospawn = no >> ~/.config/pulse/client.conf #use ~/.pulse/client.conf on Ubuntu <= 12.10 killall pulseaudio $LANG=C pulseaudio -vvvv --log-time=1 > ~/pulseverbose.log 2>&1 My sound does not work. (just with the speakers, with headphones it works but I can not change the volume) The sound icon on the top right corner does show a speaker with a single non continuous line. I can not change the volume; it is frozen. There can be an extremely low output of the sound (I hear something but I am not sure...) It does not show a single output device that is avalaible, not even the "dummie". I have tried to reset pulseaudio, alsa, remove it, purging it, reinstalling it, without having success. EDIT: I have tried launching pulseaudio via the terminal. It worked :D However, I am very surprised why it does not automatically start at the start of the computer. Any ideas ? Here the console output : W: [pulseaudio] authkey.c: Failed to open cookie file '/home/simonm/.config/pulse/cookie': No such file or directory W: [pulseaudio] authkey.c: Failed to load authorization key '/home/simonm/.config/pulse/cookie': No such file or directory W: [pulseaudio] authkey.c: Failed to open cookie file '/home/simonm/.pulse-cookie': No such file or directory W: [pulseaudio] authkey.c: Failed to load authorization key '/home/simonm/.pulse-cookie': No such file or directory

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  • What are the design principles that promote testable code? (designing testable code vs driving design through tests)

    - by bot
    Most of the projects that I work on consider development and unit testing in isolation which makes writing unit tests at a later instance a nightmare. My objective is to keep testing in mind during the high level and low level design phases itself. I want to know if there are any well defined design principles that promote testable code. One such principle that I have come to understand recently is Dependency Inversion through Dependency injection and Inversion of Control. I have read that there is something known as SOLID. I want to understand if following the SOLID principles indirectly results in code that is easily testable? If not, are there any well-defined design principles that promote testable code? I am aware that there is something known as Test Driven Development. Although, I am more interested in designing code with testing in mind during the design phase itself rather than driving design through tests. I hope this makes sense. One more question related to this topic is whether it's alright to re-factor an existing product/project and make changes to code and design for the purpose of being able to write a unit test case for each module?

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  • How do I develop database-utilizing application in an agile/test-driven-development way?

    - by user39019
    I want to add databases (traditional client/server RDBMS's like Mysql/Postgresql as opposed to NoSQL, or embedded databases) to my toolbox as a developer. I've been using SQLite for simpler projects with only 1 client, but now I want to do more complicated things (ie, db-backed web development). I usually like following agile and/or test-driven-development principles. I generally code in Perl or Python. Questions: How do I test my code such that each run of the test suite starts with a 'pristine' state? Do I run a separate instance of the database server every test? Do I use a temporary database? How do I design my tables/schema so that it is flexible with respect to changing requirements? Do I start with an ORM for my language? Or do I stick to manually coding SQL? One thing I don't find appealing is having to change more than one thing (say, the CREATE TABLE statement and associated crud statements) for one change, b/c that's error prone. On the other hand, I expect ORM's to be a low slower and harder to debug than raw SQL. What is the general strategy for migrating data between one version of the program and a newer one? Do I carefully write ALTER TABLE statements between each version, or do I dump the data and import fresh in the new version?

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  • Tips for Making this Code Testable [migrated]

    - by Jesse Bunch
    So I'm writing an abstraction layer that wraps a telephony RESTful service for sending text messages and making phone calls. I should build this in such a way that the low-level provider, in this case Twilio, can be easily swapped without having to re-code the higher level interactions. I'm using a package that is pre-built for Twilio and so I'm thinking that I need to create a wrapper interface to standardize the interaction between the Twilio service package and my application. Let us pretend that I cannot modify this pre-built package. Here is what I have so far (in PHP): <?php namespace Telephony; class Provider_Twilio implements Provider_Interface { public function send_sms(Provider_Request_SMS $request) { if (!$request->is_valid()) throw new Provider_Exception_InvalidRequest(); $sms = \Twilio\Twilio::request('SmsMessage'); $response = $sms->create(array( 'To' => $request->to, 'From' => $request->from, 'Body' => $request->body )); if ($this->_did_request_fail($response)) { throw new Provider_Exception_RequestFailed($response->message); } $response = new Provider_Response_SMS(TRUE); return $response; } private function _did_request_fail($api_response) { return isset($api_response->status); } } So the idea is that I can write another file like this for any other telephony service provided that it implements Provider_Interface making them swappable. Here are my questions: First off, do you think this is a good design? How could it be improved? Second, I'm having a hard time testing this because I need to mock out the Twilio package so that I'm not actually depending on Twilio's API for my tests to pass or fail. Do you see any strategy for mocking this out? Thanks in advance for any advice!

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  • No Unity after ubuntu 12.10 upgrade

    - by Aivaras
    After I upgraded to Ubuntu 12.10 from 12.04, there was low graphics and no Unity. Just the mouse and the wallpaper. So, I got into the terminal via Ctrl+Alt+T, launched Chrome and searched for a solution. As a result, I tried this: sudo sh amd-driver-installer-12.6-legacy-x86.x86_64.run It did not work. Then I tried this: sudo add-apt-repository ppa:makson96/fglrx sudo apt-get update sudo apt-get upgrade sudo apt-get install fglrx-legacy It did not work too. I removed the repository, got back the the xorg version to 1.13, and tried this: sudo sh /usr/share/ati/fglrx-uninstall.sh sudo apt-get remove --purge fglrx fglRx_* fglrx-amdcccle* fglrx-dev* xorg-driver-fglrx sudo apt-get remove --purge xserver-xorg-video-ati xserver-xorg-video-radeon sudo apt-get install xserver-xorg-video-ati sudo apt-get install --reinstall libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core It did return the screen resolution back, but still no Unity. Is there something what could I do? My graphics card is: lspci | grep VGA 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI RV620 [Mobility Radeon HD 3400 Series]

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  • Should I be worrying about limiting the number of textures in my game?

    - by Donutz
    I am working on a GUI in XNA 4.0 at the moment. (Before you point out that there are many GUIs already in existance, this is as much a learning exercise as a practical project). As you may know, controls and dialogs in Windows actually consist of a number of system-level windows. For instance, a dialog box may consist of a window for the whole dialog, a child window for the client area, another window (barely showing) for the frame, and so on. This makes detecting mouse hits and doing clipping relatively easy. I'd like to design my XNA GUI along the same lines, but using overlapping Textures instead of windows obviously. My question (yes, there's actually a question in this drivel) is: am I at risk of adversely affecting game performance and/or running low in resources if I get too nuts with the creating of many small textures? I haven't been able to find much information on how resource-tight the XNA environment actually is. I grew up in the days of 64K ram so I'm used to obsessing about resources and optimization. Anyway, any feedback appreciated.

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  • Function for building an isosurface (a sphere cut by planes)

    - by GameDevEnthusiast
    I want to build an octree over a quarter of a sphere (for debugging and testing). The octree generator relies on the AIsosurface interface to compute the density and normal at any given point in space. For example, for a full sphere the corresponding code is: // returns <0 if the point is inside the solid virtual float GetDensity( float _x, float _y, float _z ) const override { Float3 P = Float3_Set( _x, _y, _z ); Float3 v = Float3_Subtract( P, m_origin ); float l = Float3_LengthSquared( v ); float d = Float_Sqrt(l) - m_radius; return d; } // estimates the gradient at the given point virtual Float3 GetNormal( float _x, float _y, float _z ) const override { Float3 P = Float3_Set( _x, _y, _z ); float d = this->AIsosurface::GetDensity( P ); float Nx = this->GetDensity( _x + 0.001f, _y, _z ) - d; float Ny = this->GetDensity( _x, _y + 0.001f, _z ) - d; float Nz = this->GetDensity( _x, _y, _z + 0.001f ) - d; Float3 N = Float3_Normalized( Float3_Set( Nx, Ny, Nz ) ); return N; } What is a nice and fast way to compute those values when the shape is bounded by a low number of half-spaces?

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  • Determining the health of a Cisco switch port?

    - by ewwhite
    I've been chasing a packet-loss and network stability issue for a handful of end-users on an internal network for the past few days... These issues surfaced recently, however, the location was struck by lightning six weeks ago. I was seeing 5-10% packet loss between a stack of four Cisco 2960's and several PC's and phones on the other side of a 77-meter run. The PC's were run inline with the phones over a trunked link. We were seeing dropped calls and interruptions in client-server applications and Microsoft Exchange connectivity. I tried the usual troubleshooting steps remotely, having a local technician do the following during breaks in user and production activity: change cables between the wall jack and device. change patch cables between the patch panel and switch port(s). try different switch ports within the 2960 stack. change end-user devices with known-good equipment (new phones, different PC's). clear switch port interface counters and monitor incrementing errors closely. (Pastebin output of sh int) Pored over the device logs and Observium RRD graphs. No link up/down issues from the switch side. change power strips on the end-user side. test cable runs from the Cisco 2960 using test cable-diagnostics tdr int Gi4/0/9 (clean)* test cable runs with a Tripp-Lite cable tester. (clean) run diagnostics on the switch stack members. (clean) In the end, it took three changes of switch ports to find a stable solution. The only logical conclusion is that a few Cisco 2960 switch ports are bad or flaky... Not dead, but not consistent in behavior either. I'm not used to seeing individual ports die in this manner. What else can I test or check to determine if these devices are bad? Is it common for single ports to have problems, rather than a contiguous bank of ports? BTW - show cable-diagnostics tdr int Gi4/0/14 is very cool... Interface Speed Local pair Pair length Remote pair Pair status --------- ----- ---------- ------------------ ----------- -------------------- Gi4/0/14 1000M Pair A 79 +/- 0 meters Pair B Normal Pair B 75 +/- 0 meters Pair A Normal Pair C 77 +/- 0 meters Pair D Normal Pair D 79 +/- 0 meters Pair C Normal

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  • Is my Cisco switch port bad?

    - by ewwhite
    I've been chasing a packet-loss and network stability issue for a handful of end-users on an internal network for the past few days... These issues surfaced last week, however the location was struck by lightning six weeks ago. I was seeing 5-10% packet loss between a stack of four Cisco 2960's and several PC's and phones on the other side of a 77-meter run. The PC's were run inline with the phones over a trunked link (switchport configuration pastebin). We were seeing dropped calls and interruptions in client-server applications and Microsoft Exchange connectivity. I tried the usual troubleshooting steps remotely, having a local technician do the following during breaks in user and production activity: change cables between the wall jack and device. change patch cables between the patch panel and switch port(s). try different switch ports within the 2960 stack. change end-user devices with known-good equipment (new phones, different PC's). clear switch port interface counters and monitor incrementing errors closely. (Pastebin output of sh int) Pored over the device logs and Observium RRD graphs. No link up/down issues from the switch side. change power strips on the end-user side. test cable runs from the Cisco 2960 using test cable-diagnostics tdr int Gi4/0/9 (clean)* test cable runs with a Tripp-Lite cable tester. (clean) run diagnostics on the switch stack members. (clean) In the end, it took three changes of switch ports to find a stable solution. The only logical conclusion is that a few Cisco 2960 switch ports are bad or flaky... Not dead, but not consistent in behavior either. I'm not used to seeing individual ports die in this manner. What else can I test or check to determine if these devices are bad? Is it common for single ports to have problems, rather than a contiguous bank of ports? BTW - show cable-diagnostics tdr int Gi4/0/14 is very cool... Interface Speed Local pair Pair length Remote pair Pair status --------- ----- ---------- ------------------ ----------- -------------------- Gi4/0/14 1000M Pair A 79 +/- 0 meters Pair B Normal Pair B 75 +/- 0 meters Pair A Normal Pair C 77 +/- 0 meters Pair D Normal Pair D 79 +/- 0 meters Pair C Normal

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  • How to install missing Sound Drivers in Ubuntu?

    - by Sakamoto Kazuma
    I seem to be missing drivers for my Gateway laptop MA7. I have looked in System-Admin-Hardware Drivers, but it does not show up in there.There are also no devices listed in Sound-Hardware. I'm guessing at this point that I don't have the driver installed. However, I get the following output: admin@machine001:~$ cat /proc/asound/cards 0 [Intel ]: HDA-Intel - HDA Intel HDA Intel at 0xd8240000 irq 22 admin@machine001:~$ And my lspci shows: 00:00.0 Host bridge: Intel Corporation Mobile 945GM/PM/GMS, 943/940GML and 945GT Express Memory Controller Hub (rev 03) 00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03) 00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03) 00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 02) 00:1c.0 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 1 (rev 02) 00:1c.1 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 2 (rev 02) 00:1d.0 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #1 (rev 02) 00:1d.1 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #2 (rev 02) 00:1d.2 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #3 (rev 02) 00:1d.3 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #4 (rev 02) 00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2 EHCI Controller (rev 02) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev e2) 00:1f.0 ISA bridge: Intel Corporation 82801GBM (ICH7-M) LPC Interface Bridge (rev 02) 00:1f.1 IDE interface: Intel Corporation 82801G (ICH7 Family) IDE Controller (rev 02) 00:1f.2 SATA controller: Intel Corporation 82801GBM/GHM (ICH7 Family) SATA AHCI Controller (rev 02) 00:1f.3 SMBus: Intel Corporation 82801G (ICH7 Family) SMBus Controller (rev 02) 02:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8038 PCI-E Fast Ethernet Controller (rev 14) 03:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG [Golan] Network Connection (rev 02) 04:09.0 CardBus bridge: Texas Instruments PCIxx12 Cardbus Controller 04:09.1 FireWire (IEEE 1394): Texas Instruments PCIxx12 OHCI Compliant IEEE 1394 Host Controller 04:09.2 Mass storage controller: Texas Instruments 5-in-1 Multimedia Card Reader (SD/MMC/MS/MS PRO/xD) I have also checked alsamixer, and nothing is muted. No headphones plugged into headphone jack either. So the question now is, how do I get sound to work on my laptop? It doesn't work for any application.

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  • Using JSON.NET for dynamic JSON parsing

    - by Rick Strahl
    With the release of ASP.NET Web API as part of .NET 4.5 and MVC 4.0, JSON.NET has effectively pushed out the .NET native serializers to become the default serializer for Web API. JSON.NET is vastly more flexible than the built in DataContractJsonSerializer or the older JavaScript serializer. The DataContractSerializer in particular has been very problematic in the past because it can't deal with untyped objects for serialization - like values of type object, or anonymous types which are quite common these days. The JavaScript Serializer that came before it actually does support non-typed objects for serialization but it can't do anything with untyped data coming in from JavaScript and it's overall model of extensibility was pretty limited (JavaScript Serializer is what MVC uses for JSON responses). JSON.NET provides a robust JSON serializer that has both high level and low level components, supports binary JSON, JSON contracts, Xml to JSON conversion, LINQ to JSON and many, many more features than either of the built in serializers. ASP.NET Web API now uses JSON.NET as its default serializer and is now pulled in as a NuGet dependency into Web API projects, which is great. Dynamic JSON Parsing One of the features that I think is getting ever more important is the ability to serialize and deserialize arbitrary JSON content dynamically - that is without mapping the JSON captured directly into a .NET type as DataContractSerializer or the JavaScript Serializers do. Sometimes it isn't possible to map types due to the differences in languages (think collections, dictionaries etc), and other times you simply don't have the structures in place or don't want to create them to actually import the data. If this topic sounds familiar - you're right! I wrote about dynamic JSON parsing a few months back before JSON.NET was added to Web API and when Web API and the System.Net HttpClient libraries included the System.Json classes like JsonObject and JsonArray. With the inclusion of JSON.NET in Web API these classes are now obsolete and didn't ship with Web API or the client libraries. I re-linked my original post to this one. In this post I'll discus JToken, JObject and JArray which are the dynamic JSON objects that make it very easy to create and retrieve JSON content on the fly without underlying types. Why Dynamic JSON? So, why Dynamic JSON parsing rather than strongly typed parsing? Since applications are interacting more and more with third party services it becomes ever more important to have easy access to those services with easy JSON parsing. Sometimes it just makes lot of sense to pull just a small amount of data out of large JSON document received from a service, because the third party service isn't directly related to your application's logic most of the time - and it makes little sense to map the entire service structure in your application. For example, recently I worked with the Google Maps Places API to return information about businesses close to me (or rather the app's) location. The Google API returns a ton of information that my application had no interest in - all I needed was few values out of the data. Dynamic JSON parsing makes it possible to map this data, without having to map the entire API to a C# data structure. Instead I could pull out the three or four values I needed from the API and directly store it on my business entities that needed to receive the data - no need to map the entire Maps API structure. Getting JSON.NET The easiest way to use JSON.NET is to grab it via NuGet and add it as a reference to your project. You can add it to your project with: PM> Install-Package Newtonsoft.Json From the Package Manager Console or by using Manage NuGet Packages in your project References. As mentioned if you're using ASP.NET Web API or MVC 4 JSON.NET will be automatically added to your project. Alternately you can also go to the CodePlex site and download the latest version including source code: http://json.codeplex.com/ Creating JSON on the fly with JObject and JArray Let's start with creating some JSON on the fly. It's super easy to create a dynamic object structure with any of the JToken derived JSON.NET objects. The most common JToken derived classes you are likely to use are JObject and JArray. JToken implements IDynamicMetaProvider and so uses the dynamic  keyword extensively to make it intuitive to create object structures and turn them into JSON via dynamic object syntax. Here's an example of creating a music album structure with child songs using JObject for the base object and songs and JArray for the actual collection of songs:[TestMethod] public void JObjectOutputTest() { // strong typed instance var jsonObject = new JObject(); // you can explicitly add values here using class interface jsonObject.Add("Entered", DateTime.Now); // or cast to dynamic to dynamically add/read properties dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; album.Artist = "AC/DC"; album.YearReleased = 1976; album.Songs = new JArray() as dynamic; dynamic song = new JObject(); song.SongName = "Dirty Deeds Done Dirt Cheap"; song.SongLength = "4:11"; album.Songs.Add(song); song = new JObject(); song.SongName = "Love at First Feel"; song.SongLength = "3:10"; album.Songs.Add(song); Console.WriteLine(album.ToString()); } This produces a complete JSON structure: { "Entered": "2012-08-18T13:26:37.7137482-10:00", "AlbumName": "Dirty Deeds Done Dirt Cheap", "Artist": "AC/DC", "YearReleased": 1976, "Songs": [ { "SongName": "Dirty Deeds Done Dirt Cheap", "SongLength": "4:11" }, { "SongName": "Love at First Feel", "SongLength": "3:10" } ] } Notice that JSON.NET does a nice job formatting the JSON, so it's easy to read and paste into blog posts :-). JSON.NET includes a bunch of configuration options that control how JSON is generated. Typically the defaults are just fine, but you can override with the JsonSettings object for most operations. The important thing about this code is that there's no explicit type used for holding the values to serialize to JSON. Rather the JSON.NET objects are the containers that receive the data as I build up my JSON structure dynamically, simply by adding properties. This means this code can be entirely driven at runtime without compile time restraints of structure for the JSON output. Here I use JObject to create a album 'object' and immediately cast it to dynamic. JObject() is kind of similar in behavior to ExpandoObject in that it allows you to add properties by simply assigning to them. Internally, JObject values are stored in pseudo collections of key value pairs that are exposed as properties through the IDynamicMetaObject interface exposed in JSON.NET's JToken base class. For objects the syntax is very clean - you add simple typed values as properties. For objects and arrays you have to explicitly create new JObject or JArray, cast them to dynamic and then add properties and items to them. Always remember though these values are dynamic - which means no Intellisense and no compiler type checking. It's up to you to ensure that the names and values you create are accessed consistently and without typos in your code. Note that you can also access the JObject instance directly (not as dynamic) and get access to the underlying JObject type. This means you can assign properties by string, which can be useful for fully data driven JSON generation from other structures. Below you can see both styles of access next to each other:// strong type instance var jsonObject = new JObject(); // you can explicitly add values here jsonObject.Add("Entered", DateTime.Now); // expando style instance you can just 'use' properties dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; JContainer (the base class for JObject and JArray) is a collection so you can also iterate over the properties at runtime easily:foreach (var item in jsonObject) { Console.WriteLine(item.Key + " " + item.Value.ToString()); } The functionality of the JSON objects are very similar to .NET's ExpandObject and if you used it before, you're already familiar with how the dynamic interfaces to the JSON objects works. Importing JSON with JObject.Parse() and JArray.Parse() The JValue structure supports importing JSON via the Parse() and Load() methods which can read JSON data from a string or various streams respectively. Essentially JValue includes the core JSON parsing to turn a JSON string into a collection of JsonValue objects that can be then referenced using familiar dynamic object syntax. Here's a simple example:public void JValueParsingTest() { var jsonString = @"{""Name"":""Rick"",""Company"":""West Wind"", ""Entered"":""2012-03-16T00:03:33.245-10:00""}"; dynamic json = JValue.Parse(jsonString); // values require casting string name = json.Name; string company = json.Company; DateTime entered = json.Entered; Assert.AreEqual(name, "Rick"); Assert.AreEqual(company, "West Wind"); } The JSON string represents an object with three properties which is parsed into a JObject class and cast to dynamic. Once cast to dynamic I can then go ahead and access the object using familiar object syntax. Note that the actual values - json.Name, json.Company, json.Entered - are actually of type JToken and I have to cast them to their appropriate types first before I can do type comparisons as in the Asserts at the end of the test method. This is required because of the way that dynamic types work which can't determine the type based on the method signature of the Assert.AreEqual(object,object) method. I have to either assign the dynamic value to a variable as I did above, or explicitly cast ( (string) json.Name) in the actual method call. The JSON structure can be much more complex than this simple example. Here's another example of an array of albums serialized to JSON and then parsed through with JsonValue():[TestMethod] public void JsonArrayParsingTest() { var jsonString = @"[ { ""Id"": ""b3ec4e5c"", ""AlbumName"": ""Dirty Deeds Done Dirt Cheap"", ""Artist"": ""AC/DC"", ""YearReleased"": 1976, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/61kTaH-uZBL._AA115_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/…ASIN=B00008BXJ4"", ""Songs"": [ { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Dirty Deeds Done Dirt Cheap"", ""SongLength"": ""4:11"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Love at First Feel"", ""SongLength"": ""3:10"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Big Balls"", ""SongLength"": ""2:38"" } ] }, { ""Id"": ""7b919432"", ""AlbumName"": ""End of the Silence"", ""Artist"": ""Henry Rollins Band"", ""YearReleased"": 1992, ""Entered"": ""2012-03-16T00:13:12.2800521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/51FO3rb1tuL._SL160_AA160_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/End-Silence-Rollins-Band/dp/B0000040OX/ref=sr_1_5?ie=UTF8&qid=1302232195&sr=8-5"", ""Songs"": [ { ""AlbumId"": ""7b919432"", ""SongName"": ""Low Self Opinion"", ""SongLength"": ""5:24"" }, { ""AlbumId"": ""7b919432"", ""SongName"": ""Grip"", ""SongLength"": ""4:51"" } ] } ]"; JArray jsonVal = JArray.Parse(jsonString) as JArray; dynamic albums = jsonVal; foreach (dynamic album in albums) { Console.WriteLine(album.AlbumName + " (" + album.YearReleased.ToString() + ")"); foreach (dynamic song in album.Songs) { Console.WriteLine("\t" + song.SongName); } } Console.WriteLine(albums[0].AlbumName); Console.WriteLine(albums[0].Songs[1].SongName); } JObject and JArray in ASP.NET Web API Of course these types also work in ASP.NET Web API controller methods. If you want you can accept parameters using these object or return them back to the server. The following contrived example receives dynamic JSON input, and then creates a new dynamic JSON object and returns it based on data from the first:[HttpPost] public JObject PostAlbumJObject(JObject jAlbum) { // dynamic input from inbound JSON dynamic album = jAlbum; // create a new JSON object to write out dynamic newAlbum = new JObject(); // Create properties on the new instance // with values from the first newAlbum.AlbumName = album.AlbumName + " New"; newAlbum.NewProperty = "something new"; newAlbum.Songs = new JArray(); foreach (dynamic song in album.Songs) { song.SongName = song.SongName + " New"; newAlbum.Songs.Add(song); } return newAlbum; } The raw POST request to the server looks something like this: POST http://localhost/aspnetwebapi/samples/PostAlbumJObject HTTP/1.1User-Agent: FiddlerContent-type: application/jsonHost: localhostContent-Length: 88 {AlbumName: "Dirty Deeds",Songs:[ { SongName: "Problem Child"},{ SongName: "Squealer"}]} and the output that comes back looks like this: {  "AlbumName": "Dirty Deeds New",  "NewProperty": "something new",  "Songs": [    {      "SongName": "Problem Child New"    },    {      "SongName": "Squealer New"    }  ]} The original values are echoed back with something extra appended to demonstrate that we're working with a new object. When you receive or return a JObject, JValue, JToken or JArray instance in a Web API method, Web API ignores normal content negotiation and assumes your content is going to be received and returned as JSON, so effectively the parameter and result type explicitly determines the input and output format which is nice. Dynamic to Strong Type Mapping You can also map JObject and JArray instances to a strongly typed object, so you can mix dynamic and static typing in the same piece of code. Using the 2 Album jsonString shown earlier, the code below takes an array of albums and picks out only a single album and casts that album to a static Album instance.[TestMethod] public void JsonParseToStrongTypeTest() { JArray albums = JArray.Parse(jsonString) as JArray; // pick out one album JObject jalbum = albums[0] as JObject; // Copy to a static Album instance Album album = jalbum.ToObject<Album>(); Assert.IsNotNull(album); Assert.AreEqual(album.AlbumName,jalbum.Value<string>("AlbumName")); Assert.IsTrue(album.Songs.Count > 0); } This is pretty damn useful for the scenario I mentioned earlier - you can read a large chunk of JSON and dynamically walk the property hierarchy down to the item you want to access, and then either access the specific item dynamically (as shown earlier) or map a part of the JSON to a strongly typed object. That's very powerful if you think about it - it leaves you in total control to decide what's dynamic and what's static. Strongly typed JSON Parsing With all this talk of dynamic let's not forget that JSON.NET of course also does strongly typed serialization which is drop dead easy. Here's a simple example on how to serialize and deserialize an object with JSON.NET:[TestMethod] public void StronglyTypedSerializationTest() { // Demonstrate deserialization from a raw string var album = new Album() { AlbumName = "Dirty Deeds Done Dirt Cheap", Artist = "AC/DC", Entered = DateTime.Now, YearReleased = 1976, Songs = new List<Song>() { new Song() { SongName = "Dirty Deeds Done Dirt Cheap", SongLength = "4:11" }, new Song() { SongName = "Love at First Feel", SongLength = "3:10" } } }; // serialize to string string json2 = JsonConvert.SerializeObject(album,Formatting.Indented); Console.WriteLine(json2); // make sure we can serialize back var album2 = JsonConvert.DeserializeObject<Album>(json2); Assert.IsNotNull(album2); Assert.IsTrue(album2.AlbumName == "Dirty Deeds Done Dirt Cheap"); Assert.IsTrue(album2.Songs.Count == 2); } JsonConvert is a high level static class that wraps lower level functionality, but you can also use the JsonSerializer class, which allows you to serialize/parse to and from streams. It's a little more work, but gives you a bit more control. The functionality available is easy to discover with Intellisense, and that's good because there's not a lot in the way of documentation that's actually useful. Summary JSON.NET is a pretty complete JSON implementation with lots of different choices for JSON parsing from dynamic parsing to static serialization, to complex querying of JSON objects using LINQ. It's good to see this open source library getting integrated into .NET, and pushing out the old and tired stock .NET parsers so that we finally have a bit more flexibility - and extensibility - in our JSON parsing. Good to go! Resources Sample Test Project http://json.codeplex.com/© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  Web Api  AJAX   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Using jQuery to Insert a New Database Record

    - by Stephen Walther
    The goal of this blog entry is to explore the easiest way of inserting a new record into a database using jQuery and .NET. I’m going to explore two approaches: using Generic Handlers and using a WCF service (In a future blog entry I’ll take a look at OData and WCF Data Services). Create the ASP.NET Project I’ll start by creating a new empty ASP.NET application with Visual Studio 2010. Select the menu option File, New Project and select the ASP.NET Empty Web Application project template. Setup the Database and Data Model I’ll use my standard MoviesDB.mdf movies database. This database contains one table named Movies that looks like this: I’ll use the ADO.NET Entity Framework to represent my database data: Select the menu option Project, Add New Item and select the ADO.NET Entity Data Model project item. Name the data model MoviesDB.edmx and click the Add button. In the Choose Model Contents step, select Generate from database and click the Next button. In the Choose Your Data Connection step, leave all of the defaults and click the Next button. In the Choose Your Data Objects step, select the Movies table and click the Finish button. Unfortunately, Visual Studio 2010 cannot spell movie correctly :) You need to click on Movy and change the name of the class to Movie. In the Properties window, change the Entity Set Name to Movies. Using a Generic Handler In this section, we’ll use jQuery with an ASP.NET generic handler to insert a new record into the database. A generic handler is similar to an ASP.NET page, but it does not have any of the overhead. It consists of one method named ProcessRequest(). Select the menu option Project, Add New Item and select the Generic Handler project item. Name your new generic handler InsertMovie.ashx and click the Add button. Modify your handler so it looks like Listing 1: Listing 1 – InsertMovie.ashx using System.Web; namespace WebApplication1 { /// <summary> /// Inserts a new movie into the database /// </summary> public class InsertMovie : IHttpHandler { private MoviesDBEntities _dataContext = new MoviesDBEntities(); public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; // Extract form fields var title = context.Request["title"]; var director = context.Request["director"]; // Create movie to insert var movieToInsert = new Movie { Title = title, Director = director }; // Save new movie to DB _dataContext.AddToMovies(movieToInsert); _dataContext.SaveChanges(); // Return success context.Response.Write("success"); } public bool IsReusable { get { return true; } } } } In Listing 1, the ProcessRequest() method is used to retrieve a title and director from form parameters. Next, a new Movie is created with the form values. Finally, the new movie is saved to the database and the string “success” is returned. Using jQuery with the Generic Handler We can call the InsertMovie.ashx generic handler from jQuery by using the standard jQuery post() method. The following HTML page illustrates how you can retrieve form field values and post the values to the generic handler: Listing 2 – Default.htm <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Add Movie</title> <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> </head> <body> <form> <label>Title:</label> <input name="title" /> <br /> <label>Director:</label> <input name="director" /> </form> <button id="btnAdd">Add Movie</button> <script type="text/javascript"> $("#btnAdd").click(function () { $.post("InsertMovie.ashx", $("form").serialize(), insertCallback); }); function insertCallback(result) { if (result == "success") { alert("Movie added!"); } else { alert("Could not add movie!"); } } </script> </body> </html>     When you open the page in Listing 2 in a web browser, you get a simple HTML form: Notice that the page in Listing 2 includes the jQuery library. The jQuery library is included with the following SCRIPT tag: <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> The jQuery library is included on the Microsoft Ajax CDN so you can always easily include the jQuery library in your applications. You can learn more about the CDN at this website: http://www.asp.net/ajaxLibrary/cdn.ashx When you click the Add Movie button, the jQuery post() method is called to post the form data to the InsertMovie.ashx generic handler. Notice that the form values are serialized into a URL encoded string by calling the jQuery serialize() method. The serialize() method uses the name attribute of form fields and not the id attribute. Notes on this Approach This is a very low-level approach to interacting with .NET through jQuery – but it is simple and it works! And, you don’t need to use any JavaScript libraries in addition to the jQuery library to use this approach. The signature for the jQuery post() callback method looks like this: callback(data, textStatus, XmlHttpRequest) The second parameter, textStatus, returns the HTTP status code from the server. I tried returning different status codes from the generic handler with an eye towards implementing server validation by returning a status code such as 400 Bad Request when validation fails (see http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html ). I finally figured out that the callback is not invoked when the textStatus has any value other than “success”. Using a WCF Service As an alternative to posting to a generic handler, you can create a WCF service. You create a new WCF service by selecting the menu option Project, Add New Item and selecting the Ajax-enabled WCF Service project item. Name your WCF service InsertMovie.svc and click the Add button. Modify the WCF service so that it looks like Listing 3: Listing 3 – InsertMovie.svc using System.ServiceModel; using System.ServiceModel.Activation; namespace WebApplication1 { [ServiceBehavior(IncludeExceptionDetailInFaults=true)] [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class MovieService { private MoviesDBEntities _dataContext = new MoviesDBEntities(); [OperationContract] public bool Insert(string title, string director) { // Create movie to insert var movieToInsert = new Movie { Title = title, Director = director }; // Save new movie to DB _dataContext.AddToMovies(movieToInsert); _dataContext.SaveChanges(); // Return movie (with primary key) return true; } } }   The WCF service in Listing 3 uses the Entity Framework to insert a record into the Movies database table. The service always returns the value true. Notice that the service in Listing 3 includes the following attribute: [ServiceBehavior(IncludeExceptionDetailInFaults=true)] You need to include this attribute if you want to get detailed error information back to the client. When you are building an application, you should always include this attribute. When you are ready to release your application, you should remove this attribute for security reasons. Using jQuery with the WCF Service Calling a WCF service from jQuery requires a little more work than calling a generic handler from jQuery. Here are some good blog posts on some of the issues with using jQuery with WCF: http://encosia.com/2008/06/05/3-mistakes-to-avoid-when-using-jquery-with-aspnet-ajax/ http://encosia.com/2008/03/27/using-jquery-to-consume-aspnet-json-web-services/ http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp-net-ajax-1-0-mitigates-these-attacks.aspx http://www.west-wind.com/Weblog/posts/896411.aspx http://www.west-wind.com/weblog/posts/324917.aspx http://professionalaspnet.com/archive/tags/WCF/default.aspx The primary requirement when calling WCF from jQuery is that the request use JSON: The request must include a content-type:application/json header. Any parameters included with the request must be JSON encoded. Unfortunately, jQuery does not include a method for serializing JSON (Although, oddly, jQuery does include a parseJSON() method for deserializing JSON). Therefore, we need to use an additional library to handle the JSON serialization. The page in Listing 4 illustrates how you can call a WCF service from jQuery. Listing 4 – Default2.aspx <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Add Movie</title> <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/json2.js" type="text/javascript"></script> </head> <body> <form> <label>Title:</label> <input id="title" /> <br /> <label>Director:</label> <input id="director" /> </form> <button id="btnAdd">Add Movie</button> <script type="text/javascript"> $("#btnAdd").click(function () { // Convert the form into an object var data = { title: $("#title").val(), director: $("#director").val() }; // JSONify the data data = JSON.stringify(data); // Post it $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", url: "MovieService.svc/Insert", data: data, dataType: "json", success: insertCallback }); }); function insertCallback(result) { // unwrap result result = result["d"]; if (result === true) { alert("Movie added!"); } else { alert("Could not add movie!"); } } </script> </body> </html> There are several things to notice about Listing 4. First, notice that the page includes both the jQuery library and Douglas Crockford’s JSON2 library: <script src="Scripts/json2.js" type="text/javascript"></script> You need to include the JSON2 library to serialize the form values into JSON. You can download the JSON2 library from the following location: http://www.json.org/js.html When you click the button to submit the form, the form data is converted into a JavaScript object: // Convert the form into an object var data = { title: $("#title").val(), director: $("#director").val() }; Next, the data is serialized into JSON using the JSON2 library: // JSONify the data var data = JSON.stringify(data); Finally, the form data is posted to the WCF service by calling the jQuery ajax() method: // Post it $.ajax({   type: "POST",   contentType: "application/json; charset=utf-8",   url: "MovieService.svc/Insert",   data: data,   dataType: "json",   success: insertCallback }); You can’t use the standard jQuery post() method because you must set the content-type of the request to be application/json. Otherwise, the WCF service will reject the request for security reasons. For details, see the Scott Guthrie blog post: http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp-net-ajax-1-0-mitigates-these-attacks.aspx The insertCallback() method is called when the WCF service returns a response. This method looks like this: function insertCallback(result) {   // unwrap result   result = result["d"];   if (result === true) {       alert("Movie added!");   } else {     alert("Could not add movie!");   } } When we called the jQuery ajax() method, we set the dataType to JSON. That causes the jQuery ajax() method to deserialize the response from the WCF service from JSON into a JavaScript object automatically. The following value is passed to the insertCallback method: {"d":true} For security reasons, a WCF service always returns a response with a “d” wrapper. The following line of code removes the “d” wrapper: // unwrap result result = result["d"]; To learn more about the “d” wrapper, I recommend that you read the following blog posts: http://encosia.com/2009/02/10/a-breaking-change-between-versions-of-aspnet-ajax/ http://encosia.com/2009/06/29/never-worry-about-asp-net-ajaxs-d-again/ Summary In this blog entry, I explored two methods of inserting a database record using jQuery and .NET. First, we created a generic handler and called the handler from jQuery. This is a very low-level approach. However, it is a simple approach that works. Next, we looked at how you can call a WCF service using jQuery. This approach required a little more work because you need to serialize objects into JSON. We used the JSON2 library to perform the serialization. In the next blog post, I want to explore how you can use jQuery with OData and WCF Data Services.

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  • Where does ASP.NET Web API Fit?

    - by Rick Strahl
    With the pending release of ASP.NET MVC 4 and the new ASP.NET Web API, there has been a lot of discussion of where the new Web API technology fits in the ASP.NET Web stack. There are a lot of choices to build HTTP based applications available now on the stack - we've come a long way from when WebForms and Http Handlers/Modules where the only real options. Today we have WebForms, MVC, ASP.NET Web Pages, ASP.NET AJAX, WCF REST and now Web API as well as the core ASP.NET runtime to choose to build HTTP content with. Web API definitely squarely addresses the 'API' aspect - building consumable services - rather than HTML content, but even to that end there are a lot of choices you have today. So where does Web API fit, and when doesn't it? But before we get into that discussion, let's talk about what a Web API is and why we should care. What's a Web API? HTTP 'APIs' (Microsoft's new terminology for a service I guess)  are becoming increasingly more important with the rise of the many devices in use today. Most mobile devices like phones and tablets run Apps that are using data retrieved from the Web over HTTP. Desktop applications are also moving in this direction with more and more online content and synching moving into even traditional desktop applications. The pending Windows 8 release promises an app like platform for both the desktop and other devices, that also emphasizes consuming data from the Cloud. Likewise many Web browser hosted applications these days are relying on rich client functionality to create and manipulate the browser user interface, using AJAX rather than server generated HTML data to load up the user interface with data. These mobile or rich Web applications use their HTTP connection to return data rather than HTML markup in the form of JSON or XML typically. But an API can also serve other kinds of data, like images or other binary files, or even text data and HTML (although that's less common). A Web API is what feeds rich applications with data. ASP.NET Web API aims to service this particular segment of Web development by providing easy semantics to route and handle incoming requests and an easy to use platform to serve HTTP data in just about any content format you choose to create and serve from the server. But .NET already has various HTTP Platforms The .NET stack already includes a number of technologies that provide the ability to create HTTP service back ends, and it has done so since the very beginnings of the .NET platform. From raw HTTP Handlers and Modules in the core ASP.NET runtime, to high level platforms like ASP.NET MVC, Web Forms, ASP.NET AJAX and the WCF REST engine (which technically is not ASP.NET, but can integrate with it), you've always been able to handle just about any kind of HTTP request and response with ASP.NET. The beauty of the raw ASP.NET platform is that it provides you everything you need to build just about any type of HTTP application you can dream up from low level APIs/custom engines to high level HTML generation engine. ASP.NET as a core platform clearly has stood the test of time 10+ years later and all other frameworks like Web API are built on top of this ASP.NET core. However, although it's possible to create Web APIs / Services using any of the existing out of box .NET technologies, none of them have been a really nice fit for building arbitrary HTTP based APIs. Sure, you can use an HttpHandler to create just about anything, but you have to build a lot of plumbing to build something more complex like a comprehensive API that serves a variety of requests, handles multiple output formats and can easily pass data up to the server in a variety of ways. Likewise you can use ASP.NET MVC to handle routing and creating content in various formats fairly easily, but it doesn't provide a great way to automatically negotiate content types and serve various content formats directly (it's possible to do with some plumbing code of your own but not built in). Prior to Web API, Microsoft's main push for HTTP services has been WCF REST, which was always an awkward technology that had a severe personality conflict, not being clear on whether it wanted to be part of WCF or purely a separate technology. In the end it didn't do either WCF compatibility or WCF agnostic pure HTTP operation very well, which made for a very developer-unfriendly environment. Personally I didn't like any of the implementations at the time, so much so that I ended up building my own HTTP service engine (as part of the West Wind Web Toolkit), as have a few other third party tools that provided much better integration and ease of use. With the release of Web API for the first time I feel that I can finally use the tools in the box and not have to worry about creating and maintaining my own toolkit as Web API addresses just about all the features I implemented on my own and much more. ASP.NET Web API provides a better HTTP Experience ASP.NET Web API differentiates itself from the previous Microsoft in-box HTTP service solutions in that it was built from the ground up around the HTTP protocol and its messaging semantics. Unlike WCF REST or ASP.NET AJAX with ASMX, it’s a brand new platform rather than bolted on technology that is supposed to work in the context of an existing framework. The strength of the new ASP.NET Web API is that it combines the best features of the platforms that came before it, to provide a comprehensive and very usable HTTP platform. Because it's based on ASP.NET and borrows a lot of concepts from ASP.NET MVC, Web API should be immediately familiar and comfortable to most ASP.NET developers. Here are some of the features that Web API provides that I like: Strong Support for URL Routing to produce clean URLs using familiar MVC style routing semantics Content Negotiation based on Accept headers for request and response serialization Support for a host of supported output formats including JSON, XML, ATOM Strong default support for REST semantics but they are optional Easily extensible Formatter support to add new input/output types Deep support for more advanced HTTP features via HttpResponseMessage and HttpRequestMessage classes and strongly typed Enums to describe many HTTP operations Convention based design that drives you into doing the right thing for HTTP Services Very extensible, based on MVC like extensibility model of Formatters and Filters Self-hostable in non-Web applications  Testable using testing concepts similar to MVC Web API is meant to handle any kind of HTTP input and produce output and status codes using the full spectrum of HTTP functionality available in a straight forward and flexible manner. Looking at the list above you can see that a lot of functionality is very similar to ASP.NET MVC, so many ASP.NET developers should feel quite comfortable with the concepts of Web API. The Routing and core infrastructure of Web API are very similar to how MVC works providing many of the benefits of MVC, but with focus on HTTP access and manipulation in Controller methods rather than HTML generation in MVC. There’s much improved support for content negotiation based on HTTP Accept headers with the framework capable of detecting automatically what content the client is sending and requesting and serving the appropriate data format in return. This seems like such a little and obvious thing, but it's really important. Today's service backends often are used by multiple clients/applications and being able to choose the right data format for what fits best for the client is very important. While previous solutions were able to accomplish this using a variety of mixed features of WCF and ASP.NET, Web API combines all this functionality into a single robust server side HTTP framework that intrinsically understands the HTTP semantics and subtly drives you in the right direction for most operations. And when you need to customize or do something that is not built in, there are lots of hooks and overrides for most behaviors, and even many low level hook points that allow you to plug in custom functionality with relatively little effort. No Brainers for Web API There are a few scenarios that are a slam dunk for Web API. If your primary focus of an application or even a part of an application is some sort of API then Web API makes great sense. HTTP ServicesIf you're building a comprehensive HTTP API that is to be consumed over the Web, Web API is a perfect fit. You can isolate the logic in Web API and build your application as a service breaking out the logic into controllers as needed. Because the primary interface is the service there's no confusion of what should go where (MVC or API). Perfect fit. Primary AJAX BackendsIf you're building rich client Web applications that are relying heavily on AJAX callbacks to serve its data, Web API is also a slam dunk. Again because much if not most of the business logic will probably end up in your Web API service logic, there's no confusion over where logic should go and there's no duplication. In Single Page Applications (SPA), typically there's very little HTML based logic served other than bringing up a shell UI and then filling the data from the server with AJAX which means the business logic required for data retrieval and data acceptance and validation too lives in the Web API. Perfect fit. Generic HTTP EndpointsAnother good fit are generic HTTP endpoints that to serve data or handle 'utility' type functionality in typical Web applications. If you need to implement an image server, or an upload handler in the past I'd implement that as an HTTP handler. With Web API you now have a well defined place where you can implement these types of generic 'services' in a location that can easily add endpoints (via Controller methods) or separated out as more full featured APIs. Granted this could be done with MVC as well, but Web API seems a clearer and more well defined place to store generic application services. This is one thing I used to do a lot of in my own libraries and Web API addresses this nicely. Great fit. Mixed HTML and AJAX Applications: Not a clear Choice  For all the commonality that Web API and MVC share they are fundamentally different platforms that are independent of each other. A lot of people have asked when does it make sense to use MVC vs. Web API when you're dealing with typical Web application that creates HTML and also uses AJAX functionality for rich functionality. While it's easy to say that all 'service'/AJAX logic should go into a Web API and all HTML related generation into MVC, that can often result in a lot of code duplication. Also MVC supports JSON and XML result data fairly easily as well so there's some confusion where that 'trigger point' is of when you should switch to Web API vs. just implementing functionality as part of MVC controllers. Ultimately there's a tradeoff between isolation of functionality and duplication. A good rule of thumb I think works is that if a large chunk of the application's functionality serves data Web API is a good choice, but if you have a couple of small AJAX requests to serve data to a grid or autocomplete box it'd be overkill to separate out that logic into a separate Web API controller. Web API does add overhead to your application (it's yet another framework that sits on top of core ASP.NET) so it should be worth it .Keep in mind that MVC can generate HTML and JSON/XML and just about any other content easily and that functionality is not going away, so just because you Web API is there it doesn't mean you have to use it. Web API is not a full replacement for MVC obviously either since there's not the same level of support to feed HTML from Web API controllers (although you can host a RazorEngine easily enough if you really want to go that route) so if you're HTML is part of your API or application in general MVC is still a better choice either alone or in combination with Web API. I suspect (and hope) that in the future Web API's functionality will merge even closer with MVC so that you might even be able to mix functionality of both into single Controllers so that you don't have to make any trade offs, but at the moment that's not the case. Some Issues To think about Web API is similar to MVC but not the Same Although Web API looks a lot like MVC it's not the same and some common functionality of MVC behaves differently in Web API. For example, the way single POST variables are handled is different than MVC and doesn't lend itself particularly well to some AJAX scenarios with POST data. Code Duplication I already touched on this in the Mixed HTML and Web API section, but if you build an MVC application that also exposes a Web API it's quite likely that you end up duplicating a bunch of code and - potentially - infrastructure. You may have to create authentication logic both for an HTML application and for the Web API which might need something different altogether. More often than not though the same logic is used, and there's no easy way to share. If you implement an MVC ActionFilter and you want that same functionality in your Web API you'll end up creating the filter twice. AJAX Data or AJAX HTML On a recent post's comments, David made some really good points regarding the commonality of MVC and Web API's and its place. One comment that caught my eye was a little more generic, regarding data services vs. HTML services. David says: I see a lot of merit in the combination of Knockout.js, client side templates and view models, calling Web API for a responsive UI, but sometimes late at night that still leaves me wondering why I would no longer be using some of the nice tooling and features that have evolved in MVC ;-) You know what - I can totally relate to that. On the last Web based mobile app I worked on, we decided to serve HTML partials to the client via AJAX for many (but not all!) things, rather than sending down raw data to inject into the DOM on the client via templating or direct manipulation. While there are definitely more bytes on the wire, with this, the overhead ended up being actually fairly small if you keep the 'data' requests small and atomic. Performance was often made up by the lack of client side rendering of HTML. Server rendered HTML for AJAX templating gives so much better infrastructure support without having to screw around with 20 mismatched client libraries. Especially with MVC and partials it's pretty easy to break out your HTML logic into very small, atomic chunks, so it's actually easy to create small rendering islands that can be used via composition on the server, or via AJAX calls to small, tight partials that return HTML to the client. Although this is often frowned upon as to 'heavy', it worked really well in terms of developer effort as well as providing surprisingly good performance on devices. There's still plenty of jQuery and AJAX logic happening on the client but it's more manageable in small doses rather than trying to do the entire UI composition with JavaScript and/or 'not-quite-there-yet' template engines that are very difficult to debug. This is not an issue directly related to Web API of course, but something to think about especially for AJAX or SPA style applications. Summary Web API is a great new addition to the ASP.NET platform and it addresses a serious need for consolidation of a lot of half-baked HTTP service API technologies that came before it. Web API feels 'right', and hits the right combination of usability and flexibility at least for me and it's a good fit for true API scenarios. However, just because a new platform is available it doesn't meant that other tools or tech that came before it should be discarded or even upgraded to the new platform. There's nothing wrong with continuing to use MVC controller methods to handle API tasks if that's what your app is running now - there's very little to be gained by upgrading to Web API just because. But going forward Web API clearly is the way to go, when building HTTP data interfaces and it's good to see that Microsoft got this one right - it was sorely needed! Resources ASP.NET Web API AspConf Ask the Experts Session (first 5 minutes) © Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Setting up and using Bing Translate API Service for Machine Translation

    - by Rick Strahl
    Last week I spent quite a bit of time trying to set up the Bing Translate API service. I can honestly say this was one of the most screwed up developer experiences I've had in a long while - specifically related to the byzantine sign up process that Microsoft has in place. Not only is it nearly impossible to find decent documentation on the required signup process, some of the links in the docs are just plain wrong, and some of the account pages you need to access the actual account information once signed up are not linked anywhere from the administration UI. To make things even harder is the fact that the APIs changed a while back, with a completely new authentication scheme that's described and not directly linked documentation topic also made for a very frustrating search experience. It's a bummer that this is the case too, because the actual API itself is easy to use and works very well - fast and reasonably accurate (as accurate as you can expect machine translation to be). But the sign up process is a pain in the ass doubtlessly leaving many people giving up in frustration. In this post I'll try to hit all the points needed to set up to use the Bing Translate API in one place since such a document seems to be missing from Microsoft. Hopefully the API folks at Microsoft will get their shit together and actually provide this sort of info on their site… Signing Up The first step required is to create a Windows Azure MarketPlace account. Go to: https://datamarket.azure.com/ Sign in with your Windows Live Id If you don't have an account you will be taken to a registration page which you have to fill out. Follow the links and complete the registration. Once you're signed in you can start adding services. Click on the Data Link on the main page Select Microsoft Translator from the list This adds the Microsoft Bing Translator to your services. Pricing The page shows the pricing matrix and the free service which provides 2 megabytes for translations a month for free. Prices go up steeply from there. Pricing is determined by actual bytes of the result translations used. Max translations are 1000 characters so at minimum this means you get around 2000 translations a month for free. However most translations are probable much less so you can expect larger number of translations to go through. For testing or low volume translations this should be just fine. Once signed up there are no further instructions and you're left in limbo on the MS site. Register your Application Once you've created the Data association with Translator the next step is registering your application. To do this you need to access your developer account. Go to https://datamarket.azure.com/developer/applications/register Provide a ClientId, which is effectively the unique string identifier for your application (not your customer id!) Provide your name The client secret was auto-created and this becomes your 'password' For the redirect url provide any https url: https://microsoft.com works Give this application a description of your choice so you can identify it in the list of apps Now, once you've registered your application, keep track of the ClientId and ClientSecret - those are the two keys you need to authenticate before you can call the Translate API. Oddly the applications page is hidden from the Azure Portal UI. I couldn't find a direct link from anywhere on the site back to this page where I can examine my developer application keys. To find them you can go to: https://datamarket.azure.com/developer/applications You can come back here to look at your registered applications and pick up the ClientID and ClientSecret. Fun eh? But we're now ready to actually call the API and do some translating. Using the Bing Translate API The good news is that after this signup hell, using the API is pretty straightforward. To use the translation API you'll need to actually use two services: You need to call an authentication API service first, before you can call the actual translator API. These two APIs live on different domains, and the authentication API returns JSON data while the translator service returns XML. So much for consistency. Authentication The first step is authentication. The service uses oAuth authentication with a  bearer token that has to be passed to the translator API. The authentication call retrieves the oAuth token that you can then use with the translate API call. The bearer token has a short 10 minute life time, so while you can cache it for successive calls, the token can't be cached for long periods. This means for Web backend requests you typically will have to authenticate each time unless you build a more elaborate caching scheme that takes the timeout into account (perhaps using the ASP.NET Cache object). For low volume operations you can probably get away with simply calling the auth API for every translation you do. To call the Authentication API use code like this:/// /// Retrieves an oAuth authentication token to be used on the translate /// API request. The result string needs to be passed as a bearer token /// to the translate API. /// /// You can find client ID and Secret (or register a new one) at: /// https://datamarket.azure.com/developer/applications/ /// /// The client ID of your application /// The client secret or password /// public string GetBingAuthToken(string clientId = null, string clientSecret = null) { string authBaseUrl = https://datamarket.accesscontrol.windows.net/v2/OAuth2-13; if (string.IsNullOrEmpty(clientId) || string.IsNullOrEmpty(clientSecret)) { ErrorMessage = Resources.Resources.Client_Id_and_Client_Secret_must_be_provided; return null; } var postData = string.Format("grant_type=client_credentials&client_id={0}" + "&client_secret={1}" + "&scope=http://api.microsofttranslator.com", HttpUtility.UrlEncode(clientId), HttpUtility.UrlEncode(clientSecret)); // POST Auth data to the oauth API string res, token; try { var web = new WebClient(); web.Encoding = Encoding.UTF8; res = web.UploadString(authBaseUrl, postData); } catch (Exception ex) { ErrorMessage = ex.GetBaseException().Message; return null; } var ser = new JavaScriptSerializer(); var auth = ser.Deserialize<BingAuth>(res); if (auth == null) return null; token = auth.access_token; return token; } private class BingAuth { public string token_type { get; set; } public string access_token { get; set; } } This code basically takes the client id and secret and posts it at the oAuth endpoint which returns a JSON string. Here I use the JavaScript serializer to deserialize the JSON into a custom object I created just for deserialization. You can also use JSON.NET and dynamic deserialization if you are already using JSON.NET in your app in which case you don't need the extra type. In my library that houses this component I don't, so I just rely on the built in serializer. The auth method returns a long base64 encoded string which can be used as a bearer token in the translate API call. Translation Once you have the authentication token you can use it to pass to the translate API. The auth token is passed as an Authorization header and the value is prefixed with a 'Bearer ' prefix for the string. Here's what the simple Translate API call looks like:/// /// Uses the Bing API service to perform translation /// Bing can translate up to 1000 characters. /// /// Requires that you provide a CLientId and ClientSecret /// or set the configuration values for these two. /// /// More info on setup: /// http://www.west-wind.com/weblog/ /// /// Text to translate /// Two letter culture name /// Two letter culture name /// Pass an access token retrieved with GetBingAuthToken. /// If not passed the default keys from .config file are used if any /// public string TranslateBing(string text, string fromCulture, string toCulture, string accessToken = null) { string serviceUrl = "http://api.microsofttranslator.com/V2/Http.svc/Translate"; if (accessToken == null) { accessToken = GetBingAuthToken(); if (accessToken == null) return null; } string res; try { var web = new WebClient(); web.Headers.Add("Authorization", "Bearer " + accessToken); string ct = "text/plain"; string postData = string.Format("?text={0}&from={1}&to={2}&contentType={3}", HttpUtility.UrlEncode(text), fromCulture, toCulture, HttpUtility.UrlEncode(ct)); web.Encoding = Encoding.UTF8; res = web.DownloadString(serviceUrl + postData); } catch (Exception e) { ErrorMessage = e.GetBaseException().Message; return null; } // result is a single XML Element fragment var doc = new XmlDocument(); doc.LoadXml(res); return doc.DocumentElement.InnerText; } The first of this code deals with ensuring the auth token exists. You can either pass the token into the method manually or let the method automatically retrieve the auth code on its own. In my case I'm using this inside of a Web application and in that situation I simply need to re-authenticate every time as there's no convenient way to manage the lifetime of the auth cookie. The auth token is added as an Authorization HTTP header prefixed with 'Bearer ' and attached to the request. The text to translate, the from and to language codes and a result format are passed on the query string of this HTTP GET request against the Translate API. The translate API returns an XML string which contains a single element with the translated string. Using the Wrapper Methods It should be pretty obvious how to use these two methods but here are a couple of test methods that demonstrate the two usage scenarios:[TestMethod] public void TranslateBingWithAuthTest() { var translate = new TranslationServices(); string clientId = DbResourceConfiguration.Current.BingClientId; string clientSecret = DbResourceConfiguration.Current.BingClientSecret; string auth = translate.GetBingAuthToken(clientId, clientSecret); Assert.IsNotNull(auth); string text = translate.TranslateBing("Hello World we're back home!", "en", "de",auth); Assert.IsNotNull(text, translate.ErrorMessage); Console.WriteLine(text); } [TestMethod] public void TranslateBingIntegratedTest() { var translate = new TranslationServices(); string text = translate.TranslateBing("Hello World we're back home!","en","de"); Assert.IsNotNull(text, translate.ErrorMessage); Console.WriteLine(text); } Other API Methods The Translate API has a number of methods available and this one is the simplest one but probably also the most common one that translates a single string. You can find additional methods for this API here: http://msdn.microsoft.com/en-us/library/ff512419.aspx Soap and AJAX APIs are also available and documented on MSDN: http://msdn.microsoft.com/en-us/library/dd576287.aspx These links will be your starting points for calling other methods in this API. Dual Interface I've talked about my database driven localization provider here in the past, and it's for this tool that I added the Bing localization support. Basically I have a localization administration form that allows me to translate individual strings right out of the UI, using both Google and Bing APIs: As you can see in this example, the results from Google and Bing can vary quite a bit - in this case Google is stumped while Bing actually generated a valid translation. At other times it's the other way around - it's pretty useful to see multiple translations at the same time. Here I can choose from one of the values and driectly embed them into the translated text field. Lost in Translation There you have it. As I mentioned using the API once you have all the bureaucratic crap out of the way calling the APIs is fairly straight forward and reasonably fast, even if you have to call the Auth API for every call. Hopefully this post will help out a few of you trying to navigate the Microsoft bureaucracy, at least until next time Microsoft upends everything and introduces new ways to sign up again. Until then - happy translating… Related Posts Translation method Source on Github Translating with Google Translate without Google API Keys Creating a data-driven ASP.NET Resource Provider© Rick Strahl, West Wind Technologies, 2005-2013Posted in Localization  ASP.NET  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Built-in GZip/Deflate Compression on IIS 7.x

    - by Rick Strahl
    IIS 7 improves internal compression functionality dramatically making it much easier than previous versions to take advantage of compression that’s built-in to the Web server. IIS 7 also supports dynamic compression which allows automatic compression of content created in your own applications (ASP.NET or otherwise!). The scheme is based on content-type sniffing and so it works with any kind of Web application framework. While static compression on IIS 7 is super easy to set up and turned on by default for most text content (text/*, which includes HTML and CSS, as well as for JavaScript, Atom, XAML, XML), setting up dynamic compression is a bit more involved, mostly because the various default compression settings are set in multiple places down the IIS –> ASP.NET hierarchy. Let’s take a look at each of the two approaches available: Static Compression Compresses static content from the hard disk. IIS can cache this content by compressing the file once and storing the compressed file on disk and serving the compressed alias whenever static content is requested and it hasn’t changed. The overhead for this is minimal and should be aggressively enabled. Dynamic Compression Works against application generated output from applications like your ASP.NET apps. Unlike static content, dynamic content must be compressed every time a page that requests it regenerates its content. As such dynamic compression has a much bigger impact than static caching. How Compression is configured Compression in IIS 7.x  is configured with two .config file elements in the <system.WebServer> space. The elements can be set anywhere in the IIS/ASP.NET configuration pipeline all the way from ApplicationHost.config down to the local web.config file. The following is from the the default setting in ApplicationHost.config (in the %windir%\System32\inetsrv\config forlder) on IIS 7.5 with a couple of small adjustments (added json output and enabled dynamic compression): <?xml version="1.0" encoding="UTF-8"?> <configuration> <system.webServer> <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files"> <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> <dynamicTypes> <add mimeType="text/*" enabled="true" /> <add mimeType="message/*" enabled="true" /> <add mimeType="application/x-javascript" enabled="true" /> <add mimeType="application/json" enabled="true" /> <add mimeType="*/*" enabled="false" /> </dynamicTypes> <staticTypes> <add mimeType="text/*" enabled="true" /> <add mimeType="message/*" enabled="true" /> <add mimeType="application/x-javascript" enabled="true" /> <add mimeType="application/atom+xml" enabled="true" /> <add mimeType="application/xaml+xml" enabled="true" /> <add mimeType="*/*" enabled="false" /> </staticTypes> </httpCompression> <urlCompression doStaticCompression="true" doDynamicCompression="true" /> </system.webServer> </configuration> You can find documentation on the httpCompression and urlCompression keys here respectively: http://msdn.microsoft.com/en-us/library/ms690689%28v=vs.90%29.aspx http://msdn.microsoft.com/en-us/library/aa347437%28v=vs.90%29.aspx The httpCompression Element – What and How to compress Basically httpCompression configures what types to compress and how to compress them. It specifies the DLL that handles gzip encoding and the types of documents that are to be compressed. Types are set up based on mime-types which looks at returned Content-Type headers in HTTP responses. For example, I added the application/json to mime type to my dynamic compression types above to allow that content to be compressed as well since I have quite a bit of AJAX content that gets sent to the client. The UrlCompression Element – Enables and Disables Compression The urlCompression element is a quick way to turn compression on and off. By default static compression is enabled server wide, and dynamic compression is disabled server wide. This might be a bit confusing because the httpCompression element also has a doDynamicCompression attribute which is set to true by default, but the urlCompression attribute by the same name actually overrides it. The urlCompression element only has three attributes: doStaticCompression, doDynamicCompression and dynamicCompressionBeforeCache. The doCompression attributes are the final determining factor whether compression is enabled, so it’s a good idea to be explcit! The default for doDynamicCompression='false”, but doStaticCompression="true"! Static Compression is enabled by Default, Dynamic Compression is not Because static compression is very efficient in IIS 7 it’s enabled by default server wide and there probably is no reason to ever change that setting. Dynamic compression however, since it’s more resource intensive, is turned off by default. If you want to enable dynamic compression there are a few quirks you have to deal with, namely that enabling it in ApplicationHost.config doesn’t work. Setting: <urlCompression doDynamicCompression="true" /> in applicationhost.config appears to have no effect and I had to move this element into my local web.config to make dynamic compression work. This is actually a smart choice because you’re not likely to want dynamic compression in every application on a server. Rather dynamic compression should be applied selectively where it makes sense. However, nowhere is it documented that the setting in applicationhost.config doesn’t work (or more likely is overridden somewhere and disabled lower in the configuration hierarchy). So: remember to set doDynamicCompression=”true” in web.config!!! How Static Compression works Static compression works against static content loaded from files on disk. Because this content is static and not bound to change frequently – such as .js, .css and static HTML content – it’s fairly easy for IIS to compress and then cache the compressed content. The way this works is that IIS compresses the files into a special folder on the server’s hard disk and then reads the content from this location if already compressed content is requested and the underlying file resource has not changed. The semantics of serving an already compressed file are very efficient – IIS still checks for file changes, but otherwise just serves the already compressed file from the compression folder. The compression folder is located at: %windir%\inetpub\temp\IIS Temporary Compressed Files\ApplicationPool\ If you look into the subfolders you’ll find compressed files: These files are pre-compressed and IIS serves them directly to the client until the underlying files are changed. As I mentioned before – static compression is on by default and there’s very little reason to turn that functionality off as it is efficient and just works out of the box. The one tweak you might want to do is to set the compression level to maximum. Since IIS only compresses content very infrequently it would make sense to apply maximum compression. You can do this with the staticCompressionLevel setting on the scheme element: <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> Other than that the default settings are probably just fine. Dynamic Compression – not so fast! By default dynamic compression is disabled and that’s actually quite sensible – you should use dynamic compression very carefully and think about what content you want to compress. In most applications it wouldn’t make sense to compress *all* generated content as it would generate a significant amount of overhead. Scott Fortsyth has a great post that details some of the performance numbers and how much impact dynamic compression has. Depending on how busy your server is you can play around with compression and see what impact it has on your server’s performance. There are also a few settings you can tweak to minimize the overhead of dynamic compression. Specifically the httpCompression key has a couple of CPU related keys that can help minimize the impact of Dynamic Compression on a busy server: dynamicCompressionDisableCpuUsage dynamicCompressionEnableCpuUsage By default these are set to 90 and 50 which means that when the CPU hits 90% compression will be disabled until CPU utilization drops back down to 50%. Again this is actually quite sensible as it utilizes CPU power from compression when available and falling off when the threshold has been hit. It’s a good way some of that extra CPU power on your big servers to use when utilization is low. Again these settings are something you likely have to play with. I would probably set the upper limit a little lower than 90% maybe around 70% to make this a feature that kicks in only if there’s lots of power to spare. I’m not really sure how accurate these CPU readings that IIS uses are as Cpu usage on Web Servers can spike drastically even during low loads. Don’t trust settings – do some load testing or monitor your server in a live environment to see what values make sense for your environment. Finally for dynamic compression I tend to add one Mime type for JSON data, since a lot of my applications send large chunks of JSON data over the wire. You can do that with the application/json content type: <add mimeType="application/json" enabled="true" /> What about Deflate Compression? The default compression is GZip. The documentation hints that you can use a different compression scheme and mentions Deflate compression. And sure enough you can change the compression settings to: <scheme name="deflate" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> to get deflate style compression. The deflate algorithm produces slightly more compact output so I tend to prefer it over GZip but more HTTP clients (other than browsers) support GZip than Deflate so be careful with this option if you build Web APIs. I also had some issues with the above value actually being applied right away. Changing the scheme in applicationhost.config didn’t show up on the site  right away. It required me to do a full IISReset to get that change to show up before I saw the change over to deflate compressed content. Content was slightly more compressed with deflate – not sure if it’s worth the slightly less common compression type, but the option at least is available. IIS 7 finally makes GZip Easy In summary IIS 7 makes GZip easy finally, even if the configuration settings are a bit obtuse and the documentation is seriously lacking. But once you know the basic settings I’ve described here and the fact that you can override all of this in your local web.config it’s pretty straight forward to configure GZip support and tweak it exactly to your needs. Static compression is a total no brainer as it adds very little overhead compared to direct static file serving and provides solid compression. Dynamic Compression is a little more tricky as it does add some overhead to servers, so it probably will require some tweaking to get the right balance of CPU load vs. compression ratios. Looking at large sites like Amazon, Yahoo, NewEgg etc. – they all use Related Content Code based ASP.NET GZip Caveats HttpWebRequest and GZip Responses © Rick Strahl, West Wind Technologies, 2005-2011Posted in IIS7   ASP.NET  

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  • Enterprise Process Maps: A Process Picture worth a Million Words

    - by raul.goycoolea
    p { margin-bottom: 0.08in; }h1 { margin-top: 0.33in; margin-bottom: 0in; color: rgb(54, 95, 145); page-break-inside: avoid; }h1.western { font-family: "Cambria",serif; font-size: 14pt; }h1.cjk { font-family: "DejaVu Sans"; font-size: 14pt; }h1.ctl { font-size: 14pt; } Getting Started with Business Transformations A well-known proverb states that "A picture is worth a thousand words." In relation to Business Process Management (BPM), a credible analyst might have a few questions. What if the picture was taken from some particular angle, like directly overhead? What if it was taken from only an inch away or a mile away? What if the photographer did not focus the camera correctly? Does the value of the picture depend on who is looking at it? Enterprise Process Maps are analogous in this sense of relative value. Every BPM project (holistic BPM kick-off, enterprise system implementation, Service-oriented Architecture, business process transformation, corporate performance management, etc.) should be begin with a clear understanding of the business environment, from the biggest picture representations down to the lowest level required or desired for the particular project type, scope and objectives. The Enterprise Process Map serves as an entry point for the process architecture and is defined: the single highest level of process mapping for an organization. It is constructed and evaluated during the Strategy Phase of the Business Process Management Lifecycle. (see Figure 1) Fig. 1: Business Process Management Lifecycle Many organizations view such maps as visual abstractions, constructed for the single purpose of process categorization. This, in turn, results in a lesser focus on the inherent intricacies of the Enterprise Process view, which are explored in the course of this paper. With the main focus of a large scale process documentation effort usually underlying an ERP or other system implementation, it is common for the work to be driven by the desire to "get to the details," and to the type of modeling that will derive near-term tangible results. For instance, a project in American Pharmaceutical Company X is driven by the Director of IT. With 120+ systems in place, and a lack of standardized processes across the United States, he and the VP of IT have decided to embark on a long-term ERP implementation. At the forethought of both are questions, such as: How does my application architecture map to the business? What are each application's functionalities, and where do the business processes utilize them? Where can we retire legacy systems? Well-developed BPM methodologies prescribe numerous model types to capture such information and allow for thorough analysis in these areas. Process to application maps, Event Driven Process Chains, etc. provide this level of detail and facilitate the completion of such project-specific questions. These models and such analysis are appropriately carried out at a relatively low level of process detail. (see figure 2) Fig. 2: The Level Concept, Generic Process HierarchySome of the questions remaining are ones of documentation longevity, the continuation of BPM practice in the organization, process governance and ownership, process transparency and clarity in business process objectives and strategy. The Level Concept in Brief Figure 2 shows a generic, four-level process hierarchy depicting the breakdown of a "Process Area" into progressively more detailed process classifications. The number of levels and the names of these levels are flexible, and can be fit to the standards of the organization's chosen terminology or any other chosen reference model that makes logical sense for both short and long term process description. It is at Level 1 (in this case the Process Area level), that the Enterprise Process Map is created. This map and its contained objects become the foundation for a top-down approach to subsequent mapping, object relationship development, and analysis of the organization's processes and its supporting infrastructure. Additionally, this picture serves as a communication device, at an executive level, describing the design of the business in its service to a customer. It seems, then, imperative that the process development effort, and this map, start off on the right foot. Figuring out just what that right foot is, however, is critical and trend-setting in an evolving organization. Key Considerations Enterprise Process Maps are usually not as living and breathing as other process maps. Just as it would be an extremely difficult task to change the foundation of the Sears Tower or a city plan for the entire city of Chicago, the Enterprise Process view of an organization usually remains unchanged once developed (unless, of course, an organization is at a stage where it is capable of true, high-level process innovation). Regardless, the Enterprise Process map is a key first step, and one that must be taken in a precise way. What makes this groundwork solid depends on not only the materials used to construct it (process areas), but also the layout plan and knowledge base of what will be built (the entire process architecture). It seems reasonable that care and consideration are required to create this critical high level map... but what are the important factors? Does the process modeler need to worry about how many process areas there are? About who is looking at it? Should he only use the color pink because it's his boss' favorite color? Interestingly, and perhaps surprisingly, these are all valid considerations that may just require a bit of structure. Below are Three Key Factors to consider when building an Enterprise Process Map: Company Strategic Focus Process Categorization: Customer is Core End-to-end versus Functional Processes Company Strategic Focus As mentioned above, the Enterprise Process Map is created during the Strategy Phase of the Business Process Management Lifecycle. From Oracle Business Process Management methodology for business transformation, it is apparent that business processes exist for the purpose of achieving the strategic objectives of an organization. In a prescribed, top-down approach to process development, it must be ensured that each process fulfills its objectives, and in an aggregated manner, drives fulfillment of the strategic objectives of the company, whether for particular business segments or in a broader sense. This is a crucial point, as the strategic messages of the company must therefore resound in its process maps, in particular one that spans the processes of the complete business: the Enterprise Process Map. One simple example from Company X is shown below (see figure 3). Fig. 3: Company X Enterprise Process Map In reviewing Company X's Enterprise Process Map, one can immediately begin to understand the general strategic mindset of the organization. It shows that Company X is focused on its customers, defining 10 of its process areas belonging to customer-focused categories. Additionally, the organization views these end-customer-oriented process areas as part of customer-fulfilling value chains, while support process areas do not provide as much contiguous value. However, by including both support and strategic process categorizations, it becomes apparent that all processes are considered vital to the success of the customer-oriented focus processes. Below is an example from Company Y (see figure 4). Fig. 4: Company Y Enterprise Process Map Company Y, although also a customer-oriented company, sends a differently focused message with its depiction of the Enterprise Process Map. Along the top of the map is the company's product tree, overarching the process areas, which when executed deliver the products themselves. This indicates one strategic objective of excellence in product quality. Additionally, the view represents a less linear value chain, with strong overlaps of the various process areas. Marketing and quality management are seen as a key support processes, as they span the process lifecycle. Often, companies may incorporate graphics, logos and symbols representing customers and suppliers, and other objects to truly send the strategic message to the business. Other times, Enterprise Process Maps may show high level of responsibility to organizational units, or the application types that support the process areas. It is possible that hundreds of formats and focuses can be applied to an Enterprise Process Map. What is of vital importance, however, is which formats and focuses are chosen to truly represent the direction of the company, and serve as a driver for focusing the business on the strategic objectives set forth in that right. Process Categorization: Customer is Core In the previous two examples, processes were grouped using differing categories and techniques. Company X showed one support and three customer process categorizations using encompassing chevron objects; Customer Y achieved a less distinct categorization using a gradual color scheme. Either way, and in general, modeling of the process areas becomes even more valuable and easily understood within the context of business categorization, be it strategic or otherwise. But how one categorizes their processes is typically more complex than simply choosing object shapes and colors. Previously, it was stated that the ideal is a prescribed top-down approach to developing processes, to make certain linkages all the way back up to corporate strategy. But what about external influences? What forces push and pull corporate strategy? Industry maturity, product lifecycle, market profitability, competition, etc. can all drive the critical success factors of a particular business segment, or the company as a whole, in addition to previous corporate strategy. This may seem to be turning into a discussion of theory, but that is far from the case. In fact, in years of recent study and evolution of the way businesses operate, cross-industry and across the globe, one invariable has surfaced with such strength to make it undeniable in the game plan of any strategy fit for survival. That constant is the customer. Many of a company's critical success factors, in any business segment, relate to the customer: customer retention, satisfaction, loyalty, etc. Businesses serve customers, and so do a business's processes, mapped or unmapped. The most effective way to categorize processes is in a manner that visualizes convergence to what is core for a company. It is the value chain, beginning with the customer in mind, and ending with the fulfillment of that customer, that becomes the core or the centerpiece of the Enterprise Process Map. (See figure 5) Fig. 5: Company Z Enterprise Process Map Company Z has what may be viewed as several different perspectives or "cuts" baked into their Enterprise Process Map. It has divided its processes into three main categories (top, middle, and bottom) of Management Processes, the Core Value Chain and Supporting Processes. The Core category begins with Corporate Marketing (which contains the activities of beginning to engage customers) and ends with Customer Service Management. Within the value chain, this company has divided into the focus areas of their two primary business lines, Foods and Beverages. Does this mean that areas, such as Strategy, Information Management or Project Management are not as important as those in the Core category? No! In some cases, though, depending on the organization's understanding of high-level BPM concepts, use of category names, such as "Core," "Management" or "Support," can be a touchy subject. What is important to understand, is that no matter the nomenclature chosen, the Core processes are those that drive directly to customer value, Support processes are those which make the Core processes possible to execute, and Management Processes are those which steer and influence the Core. Some common terms for these three basic categorizations are Core, Customer Fulfillment, Customer Relationship Management, Governing, Controlling, Enabling, Support, etc. End-to-end versus Functional Processes Every high and low level of process: function, task, activity, process/work step (whatever an organization calls it), should add value to the flow of business in an organization. Suppose that within the process "Deliver package," there is a documented task titled "Stop for ice cream." It doesn't take a process expert to deduce the room for improvement. Though stopping for ice cream may create gain for the one person performing it, it likely benefits neither the organization nor, more importantly, the customer. In most cases, "Stop for ice cream" wouldn't make it past the first pass of To-Be process development. What would make the cut, however, would be a flow of tasks that, each having their own value add, build up to greater and greater levels of process objective. In this case, those tasks would combine to achieve a status of "package delivered." Figure 3 shows a simple example: Just as the package can only be delivered (outcome of the process) without first being retrieved, loaded, and the travel destination reached (outcomes of the process steps), some higher level of process "Play Practical Joke" (e.g., main process or process area) cannot be completed until a package is delivered. It seems that isolated or functionally separated processes, such as "Deliver Package" (shown in Figure 6), are necessary, but are always part of a bigger value chain. Each of these individual processes must be analyzed within the context of that value chain in order to ensure successful end-to-end process performance. For example, this company's "Create Joke Package" process could be operating flawlessly and efficiently, but if a joke is never developed, it cannot be created, so the end-to-end process breaks. Fig. 6: End to End Process Construction That being recognized, it is clear that processes must be viewed as end-to-end, customer-to-customer, and in the context of company strategy. But as can also be seen from the previous example, these vital end-to-end processes cannot be built without the functionally oriented building blocks. Without one, the other cannot be had, or at least not in a complete and organized fashion. As it turns out, but not discussed in depth here, the process modeling effort, BPM organizational development, and comprehensive coverage cannot be fully realized without a semi-functional, process-oriented approach. Then, an Enterprise Process Map should be concerned with both views, the building blocks, and access points to the business-critical end-to-end processes, which they construct. Without the functional building blocks, all streams of work needed for any business transformation would be lost mess of process disorganization. End-to-end views are essential for utilization in optimization in context, understanding customer impacts, base-lining all project phases and aligning objectives. Including both views on an Enterprise Process Map allows management to understand the functional orientation of the company's processes, while still providing access to end-to-end processes, which are most valuable to them. (See figures 7 and 8). Fig. 7: Simplified Enterprise Process Map with end-to-end Access Point The above examples show two unique ways to achieve a successful Enterprise Process Map. The first example is a simple map that shows a high level set of process areas and a separate section with the end-to-end processes of concern for the organization. This particular map is filtered to show just one vital end-to-end process for a project-specific focus. Fig. 8: Detailed Enterprise Process Map showing connected Functional Processes The second example shows a more complex arrangement and categorization of functional processes (the names of each process area has been removed). The end-to-end perspective is achieved at this level through the connections (interfaces at lower levels) between these functional process areas. An important point to note is that the organization of these two views of the Enterprise Process Map is dependent, in large part, on the orientation of its audience, and the complexity of the landscape at the highest level. If both are not apparent, the Enterprise Process Map is missing an opportunity to serve as a holistic, high-level view. Conclusion In the world of BPM, and specifically regarding Enterprise Process Maps, a picture can be worth as many words as the thought and effort that is put into it. Enterprise Process Maps alone cannot change an organization, but they serve more purposes than initially meet the eye, and therefore must be designed in a way that enables a BPM mindset, business process understanding and business transformation efforts. Every Enterprise Process Map will and should be different when looking across organizations. Its design will be driven by company strategy, a level of customer focus, and functional versus end-to-end orientations. This high-level description of the considerations of the Enterprise Process Maps is not a prescriptive "how to" guide. However, a company attempting to create one may not have the practical BPM experience to truly explore its options or impacts to the coming work of business process transformation. The biggest takeaway is that process modeling, at all levels, is a science and an art, and art is open to interpretation. It is critical that the modeler of the highest level of process mapping be a cognoscente of the message he is delivering and the factors at hand. Without sufficient focus on the design of the Enterprise Process Map, an entire BPM effort may suffer. For additional information please check: Oracle Business Process Management.

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  • CLSF & CLK 2013 Trip Report by Jeff Liu

    - by jamesmorris
    This is a contributed post from Jeff Liu, lead XFS developer for the Oracle mainline Linux kernel team. Recently, I attended both the China Linux Storage and Filesystem workshop (CLSF), and the China Linux Kernel conference (CLK), which were held in Shanghai. Here are the highlights for both events. CLSF - 17th October XFS update (led by Jeff Liu) XFS keeps rapid progress with a lot of changes, especially focused on the infrastructure/performance improvements as well as  new feature development.  This can be reflected with a sample statistics among XFS/Ext4+JBD2/Btrfs via: # git diff --stat --minimal -C -M v3.7..v3.12-rc4 -- fs/xfs|fs/ext4+fs/jbd2|fs/btrfs XFS: 141 files changed, 27598 insertions(+), 19113 deletions(-) Ext4+JBD2: 39 files changed, 10487 insertions(+), 5454 deletions(-) Btrfs: 70 files changed, 19875 insertions(+), 8130 deletions(-) What made up those changes in XFS? Self-describing metadata(CRC32c). This is a new feature and it contributed about 70% code changes, it can be enabled via `mkfs.xfs -m crc=1 /dev/xxx` for v5 superblock. Transaction log space reservation improvements. With this change, we can calculate the log space reservation at mount time rather than runtime to reduce the the CPU overhead. User namespace support. So both XFS and USERNS can be enabled on kernel configuration begin from Linux 3.10. Thanks Dwight Engen's efforts for this thing. Split project/group quota inodes. Originally, project quota can not be enabled with group quota at the same time because they were share the same quota file inode, now it works but only for v5 super block. i.e, CRC enabled. CONFIG_XFS_WARN, an new lightweight runtime debugger which can be deployed in production environment. Readahead log object recovery, this change can speed up the log replay progress significantly. Speculative preallocation inode tracking, clearing and throttling. The main purpose is to deal with inodes with post-EOF space due to speculative preallocation, support improved quota management to free up a significant amount of unwritten space when at or near EDQUOT. It support backgroup scanning which occurs on a longish interval(5 mins by default, tunable), and on-demand scanning/trimming via ioctl(2). Bitter arguments ensued from this session, especially for the comparison between Ext4 and Btrfs in different areas, I have to spent a whole morning of the 1st day answering those questions. We basically agreed on XFS is the best choice in Linux nowadays because: Stable, XFS has a good record in stability in the past 10 years. Fengguang Wu who lead the 0-day kernel test project also said that he has observed less error than other filesystems in the past 1+ years, I own it to the XFS upstream code reviewer, they always performing serious code review as well as testing. Good performance for large/small files, XFS does not works very well for small files has already been an old story for years. Best choice (maybe) for distributed PB filesystems. e.g, Ceph recommends delopy OSD daemon on XFS because Ext4 has limited xattr size. Best choice for large storage (>16TB). Ext4 does not support a single file more than around 15.95TB. Scalability, any objection to XFS is best in this point? :) XFS is better to deal with transaction concurrency than Ext4, why? The maximum size of the log in XFS is 2038MB compare to 128MB in Ext4. Misc. Ext4 is widely used and it has been proved fast/stable in various loads and scenarios, XFS just need more customers, and Btrfs is still on the road to be a manhood. Ceph Introduction (Led by Li Wang) This a hot topic.  Li gave us a nice introduction about the design as well as their current works. Actually, Ceph client has been included in Linux kernel since 2.6.34 and supported by Openstack since Folsom but it seems that it has not yet been widely deployment in production environment. Their major work is focus on the inline data support to separate the metadata and data storage, reduce the file access time, i.e, a file access need communication twice, fetch the metadata from MDS and then get data from OSD, and also, the small file access is limited by the network latency. The solution is, for the small files they would like to store the data at metadata so that when accessing a small file, the metadata server can push both metadata and data to the client at the same time. In this way, they can reduce the overhead of calculating the data offset and save the communication to OSD. For this feature, they have only run some small scale testing but really saw noticeable improvements. Test environment: Intel 2 CPU 12 Core, 64GB RAM, Ubuntu 12.04, Ceph 0.56.6 with 200GB SATA disk, 15 OSD, 1 MDS, 1 MON. The sequence read performance for 1K size files improved about 50%. I have asked Li and Zheng Yan (the core developer of Ceph, who also worked on Btrfs) whether Ceph is really stable and can be deployed at production environment for large scale PB level storage, but they can not give a positive answer, looks Ceph even does not spread over Dreamhost (subject to confirmation). From Li, they only deployed Ceph for a small scale storage(32 nodes) although they'd like to try 6000 nodes in the future. Improve Linux swap for Flash storage (led by Shaohua Li) Because of high density, low power and low price, flash storage (SSD) is a good candidate to partially replace DRAM. A quick answer for this is using SSD as swap. But Linux swap is designed for slow hard disk storage, so there are a lot of challenges to efficiently use SSD for swap. SWAPOUT swap_map scan swap_map is the in-memory data structure to track swap disk usage, but it is a slow linear scan. It will become a bottleneck while finding many adjacent pages in the use of SSD. Shaohua Li have changed it to a cluster(128K) list, resulting in O(1) algorithm. However, this apporoach needs restrictive cluster alignment and only enabled for SSD. IO pattern In most cases, the swap io is in interleaved pattern because of mutiple reclaimers or a free cluster is shared by all reclaimers. Even though block layer can merge interleaved IO to some extent, but we cannot count on it completely. Hence the per-cpu cluster is added base on the previous change, it can help reclaimer do sequential IO and the block layer will be easier to merge IO. TLB flush: If we're reclaiming one active page, we should first move the page from active lru list to inactive lru list, and then reclaim the page from inactive lru to swap it out. During the process, we need to clear PTE twice: first is 'A'(ACCESS) bit, second is 'P'(PRESENT) bit. Processors need to send lots of ipi which make the TLB flush really expensive. Some works have been done to improve this, including rework smp_call_functiom_many() or remove the first TLB flush in x86, but there still have some arguments here and only parts of works have been pushed to mainline. SWAPIN: Page fault does iodepth=1 sync io, but it's a little waste if only issue a page size's IO. The obvious solution is doing swap readahead. But the current in-kernel swap readahead is arbitary(always 8 pages), and it always doesn't perform well for both random and sequential access workload. Shaohua introduced a new flag for madvise(MADV_WILLNEED) to do swap prefetch, so the changes happen in userspace API and leave the in-kernel readahead unchanged(but I think some improvement can also be done here). SWAP discard As we know, discard is important for SSD write throughout, but the current swap discard implementation is synchronous. He changed it to async discard which allow discard and write run in the same time. Meanwhile, the unit of discard is also optimized to cluster. Misc: lock contention For many concurrent swapout and swapin , the lock contention such as anon_vma or swap_lock is high, so he changed the swap_lock to a per-swap lock. But there still have some lock contention in very high speed SSD because of swapcache address_space lock. Zproject (led by Bob Liu) Bob gave us a very nice introduction about the current memory compression status. Now there are 3 projects(zswap/zram/zcache) which all aim at smooth swap IO storm and promote performance, but they all have their own pros and cons. ZSWAP It is implemented based on frontswap API and it uses a dynamic allocater named Zbud to allocate free pages. Zbud means pairs of zpages are "buddied" and it can only store at most two compressed pages in one page frame, so the max compress ratio is 50%. Each page frame is lru-linked and can do shink in memory pressure. If the compressed memory pool reach its limitation, shink or reclaim happens. It decompress the page frame into two new allocated pages and then write them to real swap device, but it can fail when allocating the two pages. ZRAM Acts as a compressed ramdisk and used as swap device, and it use zsmalloc as its allocator which has high density but may have fragmentation issues. Besides, page reclaim is hard since it will need more pages to uncompress and free just one page. ZRAM is preferred by embedded system which may not have any real swap device. Now both ZRAM and ZSWAP are in driver/staging tree, and in the mm community there are some disscussions of merging ZRAM into ZSWAP or viceversa, but no agreement yet. ZCACHE Handles file page compression but it is removed out of staging recently. From industry (led by Tang Jie, LSI) An LSI engineer introduced several new produces to us. The first is raid5/6 cards that it use full stripe writes to improve performance. The 2nd one he introduced is SandForce flash controller, who can understand data file types (data entropy) to reduce write amplification (WA) for nearly all writes. It's called DuraWrite and typical WA is 0.5. What's more, if enable its Dynamic Logical Capacity function module, the controller can do data compression which is transparent to upper layer. LSI testing shows that with this virtual capacity enables 1x TB drive can support up to 2x TB capacity, but the application must monitor free flash space to maintain optimal performance and to guard against free flash space exhaustion. He said the most useful application is for datebase. Another thing I think it's worth to mention is that a NV-DRAM memory in NMR/Raptor which is directly exposed to host system. Applications can directly access the NV-DRAM via a memory address - using standard system call mmap(). He said that it is very useful for database logging now. This kind of NVM produces are beginning to appear in recent years, and it is said that Samsung is building a research center in China for related produces. IMHO, NVM will bring an effect to current os layer especially on file system, e.g. its journaling may need to redesign to fully utilize these nonvolatile memory. OCFS2 (led by Canquan Shen) Without a doubt, HuaWei is the biggest contributor to OCFS2 in the past two years. They have posted 46 upstream patches and 39 patches have been merged. Their current project is based on 32/64 nodes cluster, but they also tried 128 nodes at the experimental stage. The major work they are working is to support ATS (atomic test and set), it can be works with DLM at the same time. Looks this idea is inspired by the vmware VMFS locking, i.e, http://blogs.vmware.com/vsphere/2012/05/vmfs-locking-uncovered.html CLK - 18th October 2013 Improving Linux Development with Better Tools (Andi Kleen) This talk focused on how to find/solve bugs along with the Linux complexity growing. Generally, we can do this with the following kind of tools: Static code checkers tools. e.g, sparse, smatch, coccinelle, clang checker, checkpatch, gcc -W/LTO, stanse. This can help check a lot of things, simple mistakes, complex problems, but the challenges are: some are very slow, false positives, may need a concentrated effort to get false positives down. Especially, no static checker I found can follow indirect calls (“OO in C”, common in kernel): struct foo_ops { int (*do_foo)(struct foo *obj); } foo->do_foo(foo); Dynamic runtime checkers, e.g, thread checkers, kmemcheck, lockdep. Ideally all kernel code would come with a test suite, then someone could run all the dynamic checkers. Fuzzers/test suites. e.g, Trinity is a great tool, it finds many bugs, but needs manual model for each syscall. Modern fuzzers around using automatic feedback, but notfor kernel yet: http://taviso.decsystem.org/making_software_dumber.pdf Debuggers/Tracers to understand code, e.g, ftrace, can dump on events/oops/custom triggers, but still too much overhead in many cases to run always during debug. Tools to read/understand source, e.g, grep/cscope work great for many cases, but do not understand indirect pointers (OO in C model used in kernel), give us all “do_foo” instances: struct foo_ops { int (*do_foo)(struct foo *obj); } = { .do_foo = my_foo }; foo>do_foo(foo); That would be great to have a cscope like tool that understands this based on types/initializers XFS: The High Performance Enterprise File System (Jeff Liu) [slides] I gave a talk for introducing the disk layout, unique features, as well as the recent changes.   The slides include some charts to reflect the performances between XFS/Btrfs/Ext4 for small files. About a dozen users raised their hands when I asking who has experienced with XFS. I remembered that when I asked the same question in LinuxCon/Japan, only 3 people raised their hands, but they are Chris Mason, Ric Wheeler, and another attendee. The attendee questions were mainly focused on stability, and comparison with other file systems. Linux Containers (Feng Gao) The speaker introduced us that the purpose for those kind of namespaces, include mount/UTS/IPC/Network/Pid/User, as well as the system API/ABI. For the userspace tools, He mainly focus on the Libvirt LXC rather than us(LXC). Libvirt LXC is another userspace container management tool, implemented as one type of libvirt driver, it can manage containers, create namespace, create private filesystem layout for container, Create devices for container and setup resources controller via cgroup. In this talk, Feng also mentioned another two possible new namespaces in the future, the 1st is the audit, but not sure if it should be assigned to user namespace or not. Another is about syslog, but the question is do we really need it? In-memory Compression (Bob Liu) Same as CLSF, a nice introduction that I have already mentioned above. Misc There were some other talks related to ACPI based memory hotplug, smart wake-affinity in scheduler etc., but my head is not big enough to record all those things. -- Jeff Liu

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