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  • Dependency Properties

    - by developer
    Hi All, Can anybody explain me what a dependency property is in WPF and what is its use. I know there are a lot of tutorials on google for it, but they teach how to create a dependency property. I am confused as to where I would use it. I mean will I use it in XAML? If anybody could explain me in simple terms, that would be great.

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  • Create folder for todays date

    - by Ram
    Hi, I have a folder named as 2010. In this I want a folder for each month like "Jan10", "Feb10"....."Dec10" In each month folder I want to create folder for "Todays date" I have create a shortcut for that 2010 folder with Target as C:\WINDOWS\explorer.exe /n, /e, /select, F:\2010 I want a functionality that will execute when I click the shortcut for f:\2010 icon. Any pointer would be great help.

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  • Should I focus on java or on C#

    - by Daniel
    My friend started his computer engineering studies this semester, and wants to know if he should focus on Java or C#? While I am more on the Java side of life, I don't know what to answer him unbiased, so If you can give some unbiased statements on this, this would be great.

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  • using std::freopen to redirect stderr c++

    - by chriscisco
    So I want to redirect all stderr to a file, which is also being used by my logger for the entire time the application (game) is running. The follow redirect it away from the console, but it never appears in my file, and using fclose after the game loop is over doesnt actually do anything, where it would normally would. freopen(Logger::logFile.c_str(),"a",stderr); Any help would be great on how to get stderr to output to the text file, in a game loop.

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  • how can a __global__ function RETURN a value or BREAK out like C/C++ does

    - by user1684726
    Recently i've been doing string comparing jobs on CUDA, and i wonder how can a global function return a value when it finds the exact string that i'm looking for. I mean, i need the global function which contains a great amout of threads to find a certain string among a big big string-pool simultaneously, and i hope that once the exact string is caught, the global funtion can stop all the threads and return back to the main funtion, and tells me "he did it"! B.T.W., I'm using CUDA C .How could i possibly achieve that, waiting for help.

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  • when was RAII added to C++

    - by Magnus
    I recently learned about the wonderful memory management technique of RAII, which seems so much cleaner than the new/delete headache I learned in school years ago (I haven't looked at much C++ during the intervening years). I'm trying to track down when this great technique was added to C++. Was it always there and I just missed the memo? What's the oldest version of the C++ standard which supports RAII?

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  • Why are scrollbars appearing on my site on mobile devices?

    - by kcgolden
    I'm trying to make a small project site that's responsive using twitter-bootstrap and ember.js. It looks great on desktop and mostly scales to mobile devices except for one thing: x and y scrollbars appear on my android phone for the page. I don't know if this is the case on iPhone because I don't have one available at the moment. My site is here Can anyone see anything obvious in the inspector?

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  • PC: Quick Freeze, then BSOD, then forced reboot, then freezes again

    - by cr0z3r
    Lately I have been experiencing a weird issue. My PC will hang for a second and then BSOD - it stays there, so I have to reboot. Once Windows starts again and I'm logged in, after 1-10min it freezes again, this time without BSOD. RECAP: 1 second freeze BSOD, hangs there I have to force-reboot Once PC rebooted, I log back into Windows second freeze between a 1-10min range, no BSOD (alternatively, I get a freeze with a constant sound/noise, no BSOD) I contacted my PC provider, who told me my graphics-card might be flawed (Quadro 4000), so I used a Quadro 2000 that they lend me. The issue still occurred. The issue now seemed to belong to a flawed RAM module. Following my provider's steps, I removed all but the first from the left column and kept using my PC for a week or so without any issues. I then added the bottom-right module, and so on, until all modules were back inside - I had no problems. Now it seemed that a simple take-out-put-back-in of the RAM modules had fixed the issue. However, after a few months, the issue was back. I redid all the RAM-swapping I had done before, and concluded that the lower-right module was flawed. My provider changed it for another, and everything was great until now. My PC froze again for barely a second, hanged on a BSOD, I rebooted it, logged-in to Windows to get a freeze (without BSOD or reboot) 40 seconds later. Something worth noting, is that every time I reboot after the BSOD, it is something within Chrome that freezes my PC (e.g. this time I clicked the "restore" button as Chrome mentioned it had exited unexpectedly - from the previous freeze obviously - and it instantly froze). Finally, the Event Viewer lists 2 critical events in the past hour as "ID: 41, Type: Kernel-Power". PC-Specs: http://i.imgur.com/VZpbr.jpg Previous Dump-files: https://dl.dropbox.com/u/716600/DumpFiles_08_2012.zip I would like to thank anybody in advance for your help. You're great. UPDATE 1: I realized that I did not mention an awkward fact about this issue. After I have gotten the 1-sec freeze followed by a BSOD, after I rebooted because the BSOD hanged, and after I logged back in to get another (this time, eternal) freeze and rebooted once again, the PC does not boot back up. The power-light is on, but my monitor says "no signal", as if the PC wouldn't really be turned on. This truly seems a like a power-related issue, doesn't it? UPDATE 2: I just got a freeze, but without BSOD. My screen froze (while on Chrome, which is starting to seem suspicious to me) with an ongoing sound/noise. I had to force-reboot my PC. I would say this is a graphics-card issue, but this issue also happened when I was using the Quadro 2000 from my provider. UPDATE 3: I just got a BSOD while trying to render something (quite heavy, actually) in 3ds Max 2012. I left the BSOD "running", as it said it was writing dump files to disk. However, the percentage number stayed at 0, so after 15 minutes I force-rebooted. I then used the software WhoCrashed (thank you Dave) which reported the following from the C:\Windows\Memory.dmp file: On Thu 22.11.2012 22:13:45 GMT your computer crashed crash dump file: C:\Windows\memory.dmp uptime: 01:05:27 This was probably caused by the following module: Unknown () Bugcheck code: 0x124 (0x0, 0xFFFFFA80275AC028, 0xF200001F, 0x100B2) Error: WHEA_UNCORRECTABLE_ERROR Bug check description: This bug check indicates that a fatal hardware error has occurred. This bug check uses the error data that is provided by the Windows Hardware Error Architecture (WHEA). This is likely to be caused by a hardware problem problem. This problem might be caused by a thermal issue. A third party driver was identified as the probable root cause of this system error. It is suggested you look for an update for the following driver: Unknown . Google query: Unknown WHEA_UNCORRECTABLE_ERROR

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  • Using Upstart to manage Unicorn w/ rbenv + bundler binstubs w/ ruby-local-exec shebang

    - by codykrieger
    Alright, this is melting my brain. It might have something to do with the fact that I don't understand Upstart as well as I should. Sorry in advance for the long question. I'm trying to use Upstart to manage a Rails app's Unicorn master process. Here is my current /etc/init/app.conf: description "app" start on runlevel [2] stop on runlevel [016] console owner # expect daemon script APP_ROOT=/home/deploy/app PATH=/home/deploy/.rbenv/shims:/home/deploy/.rbenv/bin:$PATH $APP_ROOT/bin/unicorn -c $APP_ROOT/config/unicorn.rb -E production # >> /tmp/upstart.log 2>&1 end script # respawn That works just fine - the Unicorns start up great. What's not great is that the PID detected is not of the Unicorn master, it's of an sh process. That in and of itself isn't so bad, either - if I wasn't using the automagical Unicorn zero-downtime deployment strategy. Because shortly after I send -USR2 to my Unicorn master, a new master spawns up, and the old one dies...and so does the sh process. So Upstart thinks my job has died, and I can no longer restart it with restart or stop it with stop if I want. I've played around with the config file, trying to add -D to the Unicorn line (like this: $APP_ROOT/bin/unicorn -c $APP_ROOT/config/unicorn.rb -E production -D) to daemonize Unicorn, and I added the expect daemon line, but that didn't work either. I've tried expect fork as well. Various combinations of all of those things can cause start and stop to hang, and then Upstart gets really confused about the state of the job. Then I have to restart the machine to fix it. I think Upstart is having problems detecting when/if Unicorn is forking because I'm using rbenv + the ruby-local-exec shebang in my $APP_ROOT/bin/unicorn script. Here it is: #!/usr/bin/env ruby-local-exec # # This file was generated by Bundler. # # The application 'unicorn' is installed as part of a gem, and # this file is here to facilitate running it. # require 'pathname' ENV['BUNDLE_GEMFILE'] ||= File.expand_path("../../Gemfile", Pathname.new(__FILE__).realpath) require 'rubygems' require 'bundler/setup' load Gem.bin_path('unicorn', 'unicorn') Additionally, the ruby-local-exec script looks like this: #!/usr/bin/env bash # # `ruby-local-exec` is a drop-in replacement for the standard Ruby # shebang line: # # #!/usr/bin/env ruby-local-exec # # Use it for scripts inside a project with an `.rbenv-version` # file. When you run the scripts, they'll use the project-specified # Ruby version, regardless of what directory they're run from. Useful # for e.g. running project tasks in cron scripts without needing to # `cd` into the project first. set -e export RBENV_DIR="${1%/*}" exec ruby "$@" So there's an exec in there that I'm worried about. It fires up a Ruby process, which fires up Unicorn, which may or may not daemonize itself, which all happens from an sh process in the first place...which makes me seriously doubt the ability of Upstart to track all of this nonsense. Is what I'm trying to do even possible? From what I understand, the expect stanza in Upstart can only be told (via daemon or fork) to expect a maximum of two forks.

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  • Performance issues when using SSD for a developer notebook (WAMP/LAMP stack)?

    - by András Szepesházi
    I'm a web application developer using my notebook as a standalone development environment (WAMP stack). I just switched from a Core2-duo Vista 32 bit notebook with 2Gb RAM and SATA HDD, to an i5-2520M Win7 64 bit with 4Gb RAM and 128 GB SDD (Corsair P3 128). My initial experience was what I expected, fast boot, quick load of all the applications (Eclipse takes now 5 seconds as opposed to 30s on my old notebook), overall great experience. Then I started to build up my development stack, both as LAMP (using VirtualBox with a debian guest) and WAMP (windows native apache + mysql + php). I wanted to compare those two. This still all worked great out, then I started to pull in my projects to these stacks. And here came the nasty surprise, one of those projects produced a lot worse response times than on my old notebook (that was true for both the VirtualBox and WAMP stack). Apache, php and mysql configurations were practically identical in all environments. I started to do a lot of benchmarking and profiling, and here is what I've found: All general benchmarks (Performance Test 7.0, HDTune Pro, wPrime2 and some more) gave a big advantage to the new notebook. Nothing surprising here. Disc specific tests showed that read/write operations peaked around 380M/160M for the SSD, and all the different sized block operations also performed very well. Started apache performance benchmarking with Apache Benchmark for a small static html file (10 concurrent threads, 500 iterations). Old notebook: min 47ms, median 111ms, max 156ms New WAMP stack: min 71ms, median 135ms, max 296ms New LAMP stack (in VirtualBox): min 6ms, median 46ms, max 175ms Right here I don't get why the native WAMP stack performed so bad, but at least the LAMP environment brought the expected speed. Apache performance measurement for non-cached php content. The php runs a loop of 1000 and generates sha1(uniqid()) inisde. Again, 10 concurrent threads, 500 iterations were used for the benchmark. Old notebook: min 0ms, median 39ms, max 218ms New WAMP stack: min 20ms, median 61ms, max 186ms New LAMP stack (in VirtualBox): min 124ms, median 704ms, max 2463ms What the hell? The new LAMP performed miserably, and even the new native WAMP was outperformed by the old notebook. php + mysql test. The test consists of connecting to a database and reading a single record form a table using INNER JOIN on 3 more (indexed) tables, repeated 100 times within a loop. Databases were identical. 10 concurrent threads, 100 iterations were used for the benchmark. Old notebook: min 1201ms, median 1734ms, max 3728ms New WAMP stack: min 367ms, median 675ms, max 1893ms New LAMP stack (in VirtualBox): min 1410ms, median 3659ms, max 5045ms And the same test with concurrency set to 1 (instead of 10): Old notebook: min 1201ms, median 1261ms, max 1357ms New WAMP stack: min 399ms, median 483ms, max 539ms New LAMP stack (in VirtualBox): min 285ms, median 348ms, max 444ms Strictly for my purposes, as I'm using a self contained development environment (= low concurrency) I could be satisfied with the second test's result. Though I have no idea why the VirtualBox environment performed so bad with higher concurrency. Finally I performed a test of including many php files. The application that I mentioned at the beginning, the one that was performing so bad, has a heavy bootstrap, loads hundreds of small library and configuration files while initializing. So this test does nothing else just includes about 100 files. Concurrency set to 1, 100 iterations: Old notebook: min 140ms, median 168ms, max 406ms New WAMP stack: min 434ms, median 488ms, max 604ms New LAMP stack (in VirtualBox): min 413ms, median 1040ms, max 1921ms Even if I consider that VirtualBox reached those files via shared folders, and that slows things down a bit, I still don't see how could the old notebook outperform so heavily both new configurations. And I think this is the real root of the slow performance, as the application uses even more includes, and the whole bootstrap will occur several times within a page request (for each ajax call, for example). To sum it up, here I am with a brand new high-performance notebook that loads the same page in 20 seconds, that my old notebook can do in 5-7 seconds. Needless to say, I'm not a very happy person right now. Why do you think I experience these poor performance values? What are my options to remedy this situation?

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  • Set up lnux box for hosting a-z

    - by microchasm
    I am in the process of reinstalling the OS on a machine that will be used to host a couple of apps for our business. The apps will be local only; access from external clients will be via vpn only. The prior setup used a hosting control panel (Plesk) for most of the admin, and I was looking at using another similar piece of software for the reinstall - but I figured I should finally learn how it all works. I can do most of the things the software would do for me, but am unclear on the symbiosis of it all. This is all an attempt to further distance myself from the land of Configuration Programmer/Programmer, if at all possible. I can't find a full walkthrough anywhere for what I'm looking for, so I thought I'd put up this question, and if people can help me on the way I will edit this with the answers, and document my progress/pitfalls. Hopefully someday this will help someone down the line. The details: CentOS 5.5 x86_64 httpd: Apache/2.2.3 mysql: 5.0.77 (to be upgraded) php: 5.1 (to be upgraded) The requirements: SECURITY!! Secure file transfer Secure client access (SSL Certs and CA) Secure data storage Virtualhosts/multiple subdomains Local email would be nice, but not critical The Steps: Download latest CentOS DVD-iso (torrent worked great for me). Install CentOS: While going through the install, I checked the Server Components option thinking I was going to be using another Plesk-like admin. In hindsight, considering I've decided to try to go my own way, this probably wasn't the best idea. Basic config: Setup users, networking/ip address etc. Yum update/upgrade. Upgrade PHP: To upgrade PHP to the latest version, I had to look to another repo outside CentOS. IUS looks great and I'm happy I found it! cd /tmp #wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/x86_64/epel-release-1-1.ius.el5.noarch.rpm #rpm -Uvh epel-release-1-1.ius.el5.noarch.rpm #wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/x86_64/ius-release-1-4.ius.el5.noarch.rpm #rpm -Uvh ius-release-1-4.ius.el5.noarch.rpm yum list | grep -w \.ius\. [will list all packages available in the IUS repo] rpm -qa | grep php [will list installed packages needed to be removed. the installed packages need to be removed before you can install the IUS packages otherwise there will be conflicts] #yum shell >remove php-gd php-cli php-odbc php-mbstring php-pdo php php-xml php-common php-ldap php-mysql php-imap Setting up Remove Process >install php53 php53-mcrypt php53-mysql php53-cli php53-common php53-ldap php53-imap php53-devel >transaction solve >transaction run Leaving Shell #php -v PHP 5.3.2 (cli) (built: Apr 6 2010 18:13:45) This process removes the old version of PHP and installs the latest. To upgrade mysql: Pretty much the same process as above with PHP #/etc/init.d/mysqld stop [OK] rpm -qa | grep mysql [installed mysql packages] #yum shell >remove mysql mysql-server Setting up Remove Process >install mysql51 mysql51-server mysql51-devel >transaction solve >transaction run Leaving Shell #service mysqld start [OK] #mysql -v Server version: 5.1.42-ius Distributed by The IUS Community Project The above upgrade instructions courtesy of IUS wiki: http://wiki.iuscommunity.org/Doc/ClientUsageGuide Create a chroot jail to hold sftp user via rssh. This will force SCP/SFTP and will circumvent traditional FTP server setup. #cd /tmp #wget http://dag.wieers.com/rpm/packages/rssh/rssh-2.3.2-1.2.el5.rf.x86_64.rpm #rpm -ivh rssh-2.3.2-1.2.el5.rf.x86_64.rpm #useradd -m -d /home/dev -s /usr/bin/rssh dev #passwd dev Edit /etc/rssh.conf to grant access to SFTP to rssh users. #vi /etc/rssh.conf Uncomment line allowscp This allows me to connect to the machine via SFTP protocol in Transmit (my FTP program of choice; I'm sure it's similar with other FTP apps). Above instructions for SFTP appropriated (with appreciation!) from http://www.cyberciti.biz/tips/linux-unix-restrict-shell-access-with-rssh.html And this is where I'm at. I will keep editing this as I make progress. Any tips on how to Configure virtual interfaces/ip based virtual hosts for SSL, setting up a CA, or anything else would be appreciated.

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  • MacBook Pro 10.6 losing dns service, network connection still functional if you know the ip address.

    - by Vincent
    MacBook pro connected to a wireless network (not sure about wired) I lose DNS. I still have a functioning connection and as long as I know the ip address of the website, server... for example skype works, ssh name@ipaddress, .... Things can be working properly and then just quit, Once I was im via skype and lost dns skype continued to work. This has happened in multiple locations on private and public networks. What does not work/fix it: Resetting router changing dns server on computer or router connecting to another network removing the airport interface and adding it back flushing dns The only solution seems to be a restart. A solution to this would be great, but any ideas of this to try would be great. Even a sure way to reproduce this would be useful. Maybe related question: But this is most definitely not true for me. "if I refresh enough -- 3 to 4 times --, it will usually pull up the site. " Here are some tests from terminal. Basically this confirms dns in not functioning vmd17:~ vmd$ ping google.com ping: cannot resolve google.com: Unknown host Trace route to google dns, This works vmd17:~ vmd$ /usr/sbin/traceroute -n -w 2 -q 2 -m 30 8.8.8.8 traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 52 byte packets 1 192.168.1.1 5.195 ms 2.519 ms 2 67.172.136.1 31.881 ms 9.177 ms 3 68.85.107.121 12.168 ms 10.003 ms 4 68.86.103.41 12.021 ms 9.594 ms 5 68.86.91.1 16.712 ms 12.837 ms 6 68.86.86.210 29.951 ms 25.826 ms 7 68.86.87.218 29.554 ms 42.894 ms 8 75.149.231.70 68.271 ms 68.362 ms 9 72.14.233.77 141.178 ms 72.14.233.85 82.553 ms 10 72.14.238.243 83.381 ms 82.811 ms 11 72.14.232.213 194.387 ms 72.14.232.215 84.837 ms 12 209.85.253.145 100.294 ms * 13 8.8.8.8 101.689 ms 89.694 ms 208.67.222.22 is the ip address of opendns dns server vmd17:~ vmd$ dig @208.67.222.222 8.8.8.8 ; <<>> DiG 9.6.0-APPLE-P2 <<>> @208.67.222.222 8.8.8.8 ; (1 server found) ;; global options: +cmd ;; connection timed out; no servers could be reached vmd17:~ vmd$ dig @208.67.222.222 gogle.com vmd17:~ vmd$ dig @208.67.222.222 google.com ; <<>> DiG 9.6.0-APPLE-P2 <<>> @208.67.222.222 google.com ; (1 server found) ;; global options: +cmd ;; connection timed out; no servers could be reached vmd17:~ vmd$ dig @8.8.8.8 google.com ; <<>> DiG 9.6.0-APPLE-P2 <<>> @8.8.8.8 google.com ; (1 server found) ;; global options: +cmd ;; connection timed out; no servers could be reached

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  • Hardware recommendations / parts list for a modern, quiet ZFS NAS box - 2011-Feb edition [closed]

    - by dandv
    I want to build some really reliable storage for my data, and it seems that ZFS is the only filesystem at the moment that does live checksumming. That rules out DroboPro, so I'm looking to building a quiet ZFS NAS that would start with 4 2TB or larger hard drives. I'd like this system to be very reliable and relatively future-proof for 2-3 years, so I'm willing to invest some $$$ and buy higher end components. I did see questions here and on other forums about low-cost servers, but I'm not looking for those. I'd be super happy to go for an off-the-shelf solution, but I haven't found one that's quiet. I started doing the research (summarized on my wiki), but I realized that it just gets too complicated for what I know as a software dude, and I'm entering the analysis paralysis area. At this point, I'm basically looking for a parts list for a configuration that will work (and is modern), and I know there are folks around here who are way more competent than me. I've built computers and am comfortable assembling one and messing with *nix; I can follow guides; I just want to end the decision process for the hardware and software configuration. What I've researched so far (not that these are very modern components): Case: I think I've settled on the Antec Twelve Hundred case because it cools well, is quiet, and simply has 12 bays that allow elastic mounting. The SilverStone Raven is its counter-candidate, but I find its construction quite odd. For the PSU, I'm torn between Antec CP-850 and Nexus RX-8500, but I did this research more than a year ago. The Nexus has a very uniform power profile, and I'd rather not have the Antec spin up and down based on load. On the other hand, I'm not sure how often my file server will draw more than 400W under use. For the hard drives, I've read that WD Black drives are actually WD RE3 with a software setting changed. I'd also like to buy different drive types, not just 4 WDs. Recommendations? Right now I have a 2TB Hitachi Deskstar 7K300. For the motherboard, CPU and RAM I have no idea, other than the RAM must be ECC. I already asked a question here about ECC RAM, but I was misguided and was looking for a motherboard that would support USB 3.0 as well. I've learned to go with eSATA, or worry about USB later. Then there's the (liquid) cooling, Wi-Fi card, and FreeBSD vs. OpenSolaris Express. Lastly, I'm wondering if I can make this PC into a media server by adding a Blu-ray drive and a good sound card. But support for Blu-Ray is spotty on Linux, and I don't know if Windows 7 on VirtualBox would get sufficient hardware access to output HDMI or SPDIFF signals. (Running OpenSolaris virtualized is not an option because of the reliability risk.) Then there are HDCP concerns. Suggestions on that would be appreciated as well, but I don't want us to get sidetracked. A specific shopping list on the core components would be great, so I can start ordering, and in the meantime educate myself with regards to the other issues. Finally, I think this could become a great FAQ for those technically inclined to build their own ZFS server, but confused by the dizzying array of options out there, and I promise to compile the results and share my experience building and benchmarking the server.

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  • Asus P8P67 Rev. 3.1 Motherboard issues powering on and saving settings

    - by Scott
    Edit: New Information Have some updated information from the old question below: So basically my issue right now is somewhat similar, but I've been able to rule out a couple of things. I don't think this has anything to do with light on the motherboard. No matter what lights are on/off on the motherboard when the computer is off, they don't affect this issue. The main power LED on the Mobo is always lit when the power supply is turned on, and that's what matters anyway. Even when the main power LED is on, the PC will NOT boot up the first time I hit the power switch. I have to go reset the power supply (make all lights turn off on the Mobo and back on), and THEN hit the power switch. Then everything boots up. Also, the BIOS settings are reset every time this happens. Asus Tech Support told me to try jumping the power with something metal to try and rule out that it's a problem with the connectors getting power, or if it's a problem with the case power switch pins - haven't done that yet though. Any ideas? This is a lot simpler than it was before when I thought it had to do with certain LED indicators for RAM, EPU, etc. Original Question So I built my new desktop just about 3 weeks ago. I've been having a few issues which I think are all related to my motherboard, an Asus P8P67 Revision 3.1, but I'm not 100% sure as this is really the first from-scratch build I've ever done. I've posted these questions on the Asus forums, Asus Tech Support, and the Corsair forums as well as I thought it might have something to do with my power supply at one point. None of these avenues have solved my issue until now completely, so I thought I'd come here to see what you guys think. Here's what's happening: My computer is off, and I go to power it on. I press the power switch on the case (Antec Nine Hundred), and nothing seems to happen. Upon further inspection, I see that what this actually does is simply turn on the EPU LED on my motherboard, but doesn't actually boot anything up. I then have to go and flip the main power switch on the power supply off and back on. What this does is turn off all lights on the Motherboard after a few seconds, and turn them all back on (including the EPU LED that was off before I hit the power switch the first time). Now, hitting the power switch works. The machine boots up fine, and starts going through the boot up process. As a side note: My Motherboard is set to "Force BIOS", and every single time I change this to do the opposite, the next time my computer boots up that change reverts itself. I think this may be due to the fact that I am doing the hard reset on the power supply each time, but I'm not sure. I had thought that the Motherboard would keep its BIOS settings unless you did something to the Mobo itself - so this may be a related issue, or something else completely. That's basically it. Once it's on, it's on. It works fine, recognizes all of my hardware, and runs great. All fans/lights in the case work great, and I'm getting standard readings. The next time I go to shut the computer down however, I can expect the same exact process getting it up and running, including being forced to go into BIOS and exit again before I can load Windows. Another side note: If I power on my computer using the power switch DIRECTLY after shutting it down, it powers right back on (I think this is because the EPU LED light doesn't have time to turn off). It looks as if as long as the EPU LED is lit up on the motherboard before I hit the power switch on the case, the thing will boot up fine (although this doesn't explain the "Force BIOS" issue, at least it's something). Any ideas? Thanks guys. P.S. - System Specs Asus P8P67 Rev. 3.1 Motherboard Intel Core i7 2600K Processor 16GB (4x4GB) G-Skill 1600 RAM NVIDIA EVGA GTX 570 Video Card Crucial 128GB SSD HD Corsair 850W Power Supply Seagate 2TB HDD

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  • AWS Load balancer connection reset

    - by joshmmo
    I have an ELB set up with two instances. The issue I have with it is that when I do not add www. to it, the ELB just hangs. This is some info I get when I spider with wget: Spider mode enabled. Check if remote file exists. --2013-06-20 13:40:54-- http://learning.example.com/ Resolving learning.example.com... 54.xxx.x.x53, 50.xx.xxx.x71 Connecting to learning.example.com|54.xxx.x.x53|:80... connected. HTTP request sent, awaiting response... No data received. Retrying. when I add www. it works great. I have a GoDaddy SSL cert that I added to the listener section that covers 3 domains, www.learning.example.com, files.learning.example.com and learning.example.com. These are my listener settings: - HTTP 80 HTTPS 443 N/A N/A - SSL 443 SSL 443 Change canvasNew (Change) My EC2 instances are running apache2 on Ubuntu 12.04. I will be happy to post my vhosts file if needed. However, when I ran the server with the domains pointing to just one EC2 instance things worked fine. How can I fix this issue for learning.example.com? Why does www work just fine? A second question would be what is the difference between instance protocol and load balancer protocol? EDIT: Here are the dig results for learning.example.com from yesterday. I changed the DNS entry to point to one instance to make sure it was the elb. When I switch it back I will do it for www.learning.example.com ; <<>> DiG 9.9.1-P2 <<>> learning.example.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20210 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;learning.example.com. IN A ;; ANSWER SECTION: learning.example.com. 2559 IN CNAME canvas-22222222222.us-west-1.elb.amazonaws.com. canvas-22222222222.us-west-1.elb.amazonaws.com. 60 IN A 54.xxx.x.x53 canvas-22222222222.us-west-1.elb.amazonaws.com. 60 IN A 50.xx.xxx.x71 ;; Query time: 83 msec ;; SERVER: 10.x.xx.20#53(10.x.xx.20) ;; WHEN: Thu Jun 20 13:40:47 2013 ;; MSG SIZE rcvd: 137 EDIT 2: Here is some more info that might be helpful. Port Configuration: 80 (HTTP) forwarding to 443 (HTTPS) Backend Authentication: Disabled Stickiness: Disabled(edit) 443 (SSL, Certificate: canvasNew) forwarding to 443 (SSL) Backend Authentication: Disabled So I switched everything to one EC2 IP address to bypass the elb to make sure things are working. It's running great. www and the non-www url work perfectly fine. Its only when I switch things to the ELB that learning.example.com hangs and www.learning.example.com works. Hopefully you can get some ideas flowing.

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  • batch file to deploy files

    - by Martin Michalak
    hi I have created batch file which pulls info from *.txt file and deploy code from the source to destination: SET Source=%1 if exist %Source% ( ECHO Source for WEB exists ) else ( ECHO Wrong build%Source% doesn't exist GOTO Menu ) SET Server=%2 SET AppPool=%3 SET Destination=%4 SET Folder=%5 SET ENV=%6 SET AppName=%7 SET Envlog=%8 ECHO Deployment of WEB > %Envlog% %Date% %Time% echo. @ECHO Stopping App Pools @ECHO Stopping App Pools >> %Envlog% %Date% %Time% D:\ICTTools\PSEXEC.EXE -d \\%Server% cmd.exe /c c:\windows\system32\inetsrv\appcmd STOP apppool /apppool.name:%AppPool% echo. @ECHO App Pools will be stopped in the background @ECHO App Pools will be stopped in the background >> %Envlog% %Date% %Time% Pause echo. IF EXIST "%Destination%" ( ECHO Deleting %AppName% %Folder% RMDIR %Destination% /s /q ECHO Destination Folder %Folder% Deleted ECHO Destination Folder %Folder% Deleted >> %Envlog% %Date% %Time% ) else ( ECHO Destination Folder %Destination% does not exist, please check ECHO Destination Folder %Destination% does not exist, please check >> %Envlog% %Date% %Time% Pause ) echo. @ECHO Starting Robocopy for %AppName% @ECHO Starting Robocopy for %AppName% >> %Envlog% %Date% %Time% echo. START /WAIT /MIN ROBOCOPY.EXE %Source% %Destination% *.* /S /NP /R:3 /W:5 /LOG:"Logs\Robo%AppName%%ENV%.log" D:\Tools\Windiff\windiff.exe %Source% %Destination% echo. @ECHO Finished with Robocopy @ECHO Finished with Robocopy >> %Envlog% %Date% %Time% echo. @ECHO Checking if App pools stopped: @ECHO Checking if App pools stopped: >> %Envlog% %Date% %Time% D:\ICTTools\PSEXEC.EXE \\%Server% c:\windows\system32\inetsrv\appcmd LIST apppool /apppool.name:%AppPool% @echo off set /p ask=All app pools stopped? (y/n) if %ask%==y (echo Great, please continue with deployemnt) else echo Before continuing please check why app pools did not stop @echo App pools stopped?: %ask% >> %Envlog% %Date% %Time% DEL %Source%\web.config echo. @ECHO Production Config check if exist "%Destination%\%ENV%-Web.config" ( echo. ECHO The Application production configuration file does exist. ECHO The Application production configuration file does exist. >> %Envlog% %Date% %Time% COPY %Destination%\%ENV%-Web.config web.config echo. ECHO Production %ENV%-Web.config has been renamed to web.config ECHO Production %ENV%-Web.config has been renamed to web.config >> %Envlog% %Date% %Time% ) else ( ECHO The Application production configuration file is missing in Production %AppName% ECHO The Application production configuration file is missing in Production %AppName% >> %Envlog% %Date% %Time% explorer %Destination% Pause ) echo. @ECHO Confirm that configs were renamed correclty, if yes please hit any key to START APP Pools @ECHO Confirm that configs were renamed correclty, if yes please hit any key to START APP Pools >> %Envlog% %Date% %Time% Pause echo. @ECHO Start %AppName% Application Pool >> %Envlog% %Date% %Time% D:\ICTTools\PSEXEC.EXE \\%Server% c:\windows\system32\inetsrv\appcmd START apppool /apppool.name:%AppPool% @echo off set /p ask=All app pools started? (y/n) if %ask%==y (echo Great, please continue with deployemnt) else echo Before continuing please check why app pools did not start @echo App pools started?: %ask% >> %Envlog% %Date% %Time% Pause echo. @ECHO Build Version for %AppName% @ECHO Build Version for %AppName% >> %Envlog% %Date% %Time% type %Destination%\buildinfo.xml echo. ECHO ............................................... @ECHO ...........Deployment Compelted................ @ECHO ...........Deployment Compelted................>> %Envlog% %Date% %Time% ECHO ............................................... here are my issues: Lets say I am running code for 3 servers, then for each instance: For all three servers I am performing destination folder delete even so destination folder is always the same, the code should only delete it in the 1st instance (when code is deployed to first server) then I would prefer if script would check if the code from the source and destination is the same and if it is it should delete the folder or not. Then based on 1: a) deleting web.config and renaming should only happen if code in destination is new b) Robocopy should not override files if they are the same I think there is /Xo option to do that any idea how to achieve that? :)

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  • Set up lnux box for hosting a-z [apache mysql php ssl]

    - by microchasm
    I am in the process of reinstalling the OS on a machine that will be used to host a couple of apps for our business. The apps will be local only; access from external clients will be via vpn only. The prior setup used a hosting control panel (Plesk) for most of the admin, and I was looking at using another similar piece of software for the reinstall - but I figured I should finally learn how it all works. I can do most of the things the software would do for me, but am unclear on the symbiosis of it all. This is all an attempt to further distance myself from the land of Configuration Programmer/Programmer, if at all possible. I can't find a full walkthrough anywhere for what I'm looking for, so I thought I'd put up this question, and if people can help me on the way I will edit this with the answers, and document my progress/pitfalls. Hopefully someday this will help someone down the line. The details: CentOS 5.5 x86_64 httpd: Apache/2.2.3 mysql: 5.0.77 (to be upgraded) php: 5.1 (to be upgraded) The requirements: SECURITY!! Secure file transfer Secure client access (SSL Certs and CA) Secure data storage Virtualhosts/multiple subdomains Local email would be nice, but not critical The Steps: Download latest CentOS DVD-iso (torrent worked great for me). Install CentOS: While going through the install, I checked the Server Components option thinking I was going to be using another Plesk-like admin. In hindsight, considering I've decided to try to go my own way, this probably wasn't the best idea. Basic config: Setup users, networking/ip address etc. Yum update/upgrade. Upgrade PHP: To upgrade PHP to the latest version, I had to look to another repo outside CentOS. IUS looks great and I'm happy I found it! cd /tmp #wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/x86_64/epel-release-1-1.ius.el5.noarch.rpm #rpm -Uvh epel-release-1-1.ius.el5.noarch.rpm #wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/x86_64/ius-release-1-4.ius.el5.noarch.rpm #rpm -Uvh ius-release-1-4.ius.el5.noarch.rpm yum list | grep -w \.ius\. [will list all packages available in the IUS repo] rpm -qa | grep php [will list installed packages needed to be removed. the installed packages need to be removed before you can install the IUS packages otherwise there will be conflicts] #yum shell >remove php-gd php-cli php-odbc php-mbstring php-pdo php php-xml php-common php-ldap php-mysql php-imap Setting up Remove Process >install php53 php53-mcrypt php53-mysql php53-cli php53-common php53-ldap php53-imap php53-devel >transaction solve >transaction run Leaving Shell #php -v PHP 5.3.2 (cli) (built: Apr 6 2010 18:13:45) This process removes the old version of PHP and installs the latest. To upgrade mysql: Pretty much the same process as above with PHP #/etc/init.d/mysqld stop [OK] rpm -qa | grep mysql [installed mysql packages] #yum shell >remove mysql mysql-server Setting up Remove Process >install mysql51 mysql51-server mysql51-devel >transaction solve >transaction run Leaving Shell #service mysqld start [OK] #mysql -v Server version: 5.1.42-ius Distributed by The IUS Community Project And this is where I'm at. I will keep editing this as I make progress. Any tips on how to Configure Virtualhosts for SSL, setting up a CA, setting up SFTP with openSSH, or anything else would be appreciated.

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  • Log transport and aggregation at scale

    - by markdrayton
    How're you analysing log files from UNIX/Linux machines? We run several hundred servers which all generate their own log files, either directly or through syslog. I'm looking for a decent solution to aggregate these and pick out important events. This problem breaks down into 3 components: 1) Message transport The classic way is to use syslog to log messages to a remote host. This works fine for applications that log into syslog but less useful for apps that write to a local file. Solutions for this might include having the application log into a FIFO connected to a program to send the message using syslog, or by writing something that will grep the local files and send the output to the central syslog host. However, if we go to the trouble of writing tools to get messages into syslog would we be better replacing the whole lot with something like Facebook's Scribe which offers more flexibility and reliability than syslog? 2) Message aggregation Log entries seem to fall into one of two types: per-host and per-service. Per-host messages are those which occur on one machine; think disk failures or suspicious logins. Per-service messages occur on most or all of the hosts running a service. For instance, we want to know when Apache finds an SSI error but we don't want the same error from 100 machines. In all cases we only want to see one of each type of message: we don't want 10 messages saying the same disk has failed, and we don't want a message each time a broken SSI is hit. One approach to solving this is to aggregate multiple messages of the same type into one on each host, send the messages to a central server and then aggregate messages of the same kind into one overall event. SER can do this but it's awkward to use. Even after a couple of days of fiddling I had only rudimentary aggregations working and had to constantly look up the logic SER uses to correlate events. It's powerful but tricky stuff: I need something which my colleagues can pick up and use in the shortest possible time. SER rules don't meet that requirement. 3) Generating alerts How do we tell our admins when something interesting happens? Mail the group inbox? Inject into Nagios? So, how're you solving this problem? I don't expect an answer on a plate; I can work out the details myself but some high-level discussion on what is surely a common problem would be great. At the moment we're using a mishmash of cron jobs, syslog and who knows what else to find events. This isn't extensible, maintainable or flexible and as such we miss a lot of stuff we shouldn't. Updated: we're already using Nagios for monitoring which is great for detected down hosts/testing services/etc but less useful for scraping log files. I know there are log plugins for Nagios but I'm interested in something more scalable and hierarchical than per-host alerts.

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  • Cablemodem (SBG6580) firewall denying some outbound traffic? Why? Not configured [migrated]

    - by lairdb
    I finally got around to turning the syslog on for my cablemodem (Motorola Surfboard SBG6580) and I'm seeing about the expected amount of inbound attackage being blocked... 2014-05-30 21:59:02 Local0.Alert 192.168.111.1 May 31 04:58:56 2014 SYSLOG[0]: [Host 192.168.111.1] UDP 12.230.209.198,4500 --> 66.27.xx.xx,61459 DENY:Firewall interface [IP Fragmented Packet] attack 2014-05-30 21:59:02 Local0.Alert 192.168.111.1 May 31 04:58:56 2014 SYSLOG[0]: [Host 192.168.111.1] TCP 17.172.232.109,5223 --> 66.27.xx.xx,53814 DENY:Firewall interface access request 2014-05-30 21:59:02 Local0.Alert 192.168.111.1 May 31 04:58:57 2014 SYSLOG[0]: [Host 192.168.111.1] UDP 12.230.209.198,443 --> 66.27.xx.xx,53385 DENY: Firewall interface [IP Fragmented Packet] attack 2014-05-30 21:59:02 Local0.Alert 192.168.111.1 May 31 04:58:57 2014 SYSLOG[0]: [Host 192.168.111.1] UDP 12.230.209.198,4500 --> 66.27.xx.xx,61459 DENY:Firewall interface [IP Fragmented Packet] attack 2014-05-30 21:59:10 Local0.Alert 192.168.111.1 May 31 04:59:04 2014 SYSLOG[0]: [Host 192.168.111.1] UDP 12.230.209.198,443 --> 66.27.xx.xx,59960 DENY: Firewall interface [IP Fragmented Packet] attack 2014-05-30 21:59:10 Local0.Alert 192.168.111.1 May 31 04:59:04 2014 SYSLOG[0]: [Host 192.168.111.1] UDP 12.230.209.198,4500 --> 66.27.xx.xx,61459 DENY:Firewall interface [IP Fragmented Packet] attack ...and that's great. (Sad, but great.) But I'm also seeing a HUGE amount of what appears to be denied outbound connectivity: 2014-05-30 16:30:10 Local0.Alert 192.168.111.1 May 30 23:30:04 2014 SYSLOG[0]: [Host 192.168.111.1] TCP 192.168.111.100,58969 --> 38.81.66.127,443 DENY: Inbound or outbound access request 2014-05-30 16:30:10 Local0.Alert 192.168.111.1 May 30 23:30:04 2014 SYSLOG[0]: [Host 192.168.111.1] TCP 192.168.111.100,58969 --> 38.81.66.127,443 DENY: Inbound or outbound access request 2014-05-30 16:30:10 Local0.Alert 192.168.111.1 May 30 23:30:04 2014 SYSLOG[0]: [Host 192.168.111.1] TCP 192.168.111.100,58965 --> 162.222.41.13,443 DENY: Inbound or outbound access request 2014-05-30 16:30:10 Local0.Alert 192.168.111.1 May 30 23:30:04 2014 SYSLOG[0]: [Host 192.168.111.1] TCP 192.168.111.100,58965 --> 162.222.41.13,443 DENY: Inbound or outbound access request 2014-05-30 16:30:10 Local0.Alert 192.168.111.1 May 30 23:30:04 2014 SYSLOG[0]: [Host 192.168.111.1] TCP 192.168.111.100,58964 --> 38.81.66.179,443 DENY: Inbound or outbound access request 2014-05-30 16:30:10 Local0.Alert 192.168.111.1 May 30 23:30:04 2014 SYSLOG[0]: [Host 192.168.111.1] TCP 192.168.111.100,58964 --> 38.81.66.179,443 DENY: Inbound or outbound access request ...and Spot checking suggests that it's all legitimate traffic (Opening connections to CrashPlan, etc.), I have no restrictions configured in the modem; I don't see why it should be blocking anything. Am I misreading the log entry, and it's not actually being denied? (Seems unlikely.) Is the ISP (TWC) pushing deny tables that are not exposed in the UI? (Tinfoil hat too tight.) I'm confused. (The good news, such as it is, is that AFAIK I'm not experiencing any actual issues... but maybe I am; tough to tell.) Thanks.

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  • How To Start Your Own Professional Blog with WordPress

    - by Matthew Guay
    Would you like to start your own blog or website?  With a free WordPress  account, it’s free and easy to get started creating your own professional quality blog site. This is the first part in a series on how to create your own professional quality blog site. No, we’re not talking about some cheapo looking blog from Blogger or something on Facebook, but creating a quality blog you can be proud of and present to millions of readers online. WordPress is one of the most popular blogging platforms, powering hundreds of high-profile websites and blogs around the world.  It’s both powerful and easy to use, which makes it great whether you’re just starting out or are a blogging pro.  To start out with your blogging project WordPress is completely free, and you can use the online interface or install the WordPress software on your own server and blog from there. Getting Started You can start a blog in just a few minutes.  Head over to WordPress.com and click Sign up now on the right-hand side of the main page. Enter a username and password, check that you agree with the legal terms, select the “Gimme a blog” bullet, and click Next. WordPress may inform you that your username is already taken, simply choose a new one and try again. Next, choose a domain for your blog.  This will be the address for your site, and cannot be changed, so be sure to choose exactly what you want.  If you’d prefer your address to be yourname.com instead of yourname.wordpress.com, you can add your own domain for a fee after your blog is setup…but we’ll cover that later. Once you click signup, you will be sent a confirmation email.  While you wait for the email to arrive you can go ahead and enter in your name and a short bio about yourself. When you receive your confirmation email, click the link.  Congratulations; you now have your own blog! You can view your new blog immediately, though the default theme isn’t very interesting without your content and pictures. Back on the page you opened from the email, click Login to access your blog’s administration page and to start adding stuff to your blog.  You can also access your blog’s admin page anytime by from yourname.wordpress.com/admin, substituting your own blog name for yourname. Enter your username and password, then click Log in to get started. Adding Content to your WordPress.com Blog When you sign in to your WordPress blog, you’ll first see the WordPress Admin page.  Here you can see recent posts and comments, and you can see stats of how many people have visited your site.  You can also access all of your blog tools and settings right from this page. To add a new post to your blog, click the Posts link on the left, then click “Add New” either on the left menu or on the top of the Edit Posts page.  Or, if you want to edit the default first post, hover over it and select Edit. Or click the New Posts button on the top of the page.  This menu bar is always visible whenever you’re logged in, so it’s an easy way to add a post. The editor lets you easily write anything you want in a Microsoft Word-style editor.  You can format your text, add lists, links, quotes, and more.  When you’re ready to share your content with the world, click Publish on the right side. To add pictures or other files, click the picture icon beside “Upload/Insert”.  Your free blog account can store up to 3Gb of pictures and documents which will definitely give you a good start. Click Select Files, and then choose the pictures or documents you want to add to your post. When the pictures have uploaded, you can add a caption and choose how to position the picture.  When you’re finished, select “Insert into Post”.   Or, if you want to add a video, click the video button.  You have to add a paid upgrade to upload videos directly, but you can add YouTube and other online videos for free. Click the “From URL” tab, and then paste the link to the YouTube video and click Insert into post. If you’re a code geek, click the HTML tab in the editor and edit the HTML of your blog post the geeky way. Once you’ve added all your content and edited it the way you want, click the Publish button on the right of the editor.  Or, you can click Preview to make sure it looks right, and then click Publish. Here’s our blog with the new blog post containing a picture and video.  While you’re getting to know you’re way around the controls in WordPress, the Preview feature will be your best friend while you try to organize the content to your liking.   Conclusion It only takes a couple minutes to get started blogging at WordPress.com. Whether you want to write about your daily life, share pictures of your children, or review the latest books and gadgets, WordPress.com is a great place to get started for free.  But we’ve only covered a small portion of the WordPress features…but this should get you started. Check back for more WordPress and blogging coverage coming up soon! Links Signup for a free WordPress.com account Similar Articles Productive Geek Tips Add Social Bookmarking (Digg This!) Links to your Wordpress BlogHow-To Geek SoftwareProtecting Your WordPress Admin Panel From Hackers With .htaccessMake a Backup Copy of your Production Wordpress Blog on UbuntuLinux QuickTip: Downloading and Un-tarring in One Step TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Awe inspiring, inter-galactic theme (Win 7) Case Study – How to Optimize Popular Wordpress Sites Restore Hidden Updates in Windows 7 & Vista Iceland an Insurance Job? Find Downloads and Add-ins for Outlook Recycle !

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  • An Introduction to ASP.NET Web API

    - by Rick Strahl
    Microsoft recently released ASP.NET MVC 4.0 and .NET 4.5 and along with it, the brand spanking new ASP.NET Web API. Web API is an exciting new addition to the ASP.NET stack that provides a new, well-designed HTTP framework for creating REST and AJAX APIs (API is Microsoft’s new jargon for a service, in case you’re wondering). Although Web API ships and installs with ASP.NET MVC 4, you can use Web API functionality in any ASP.NET project, including WebForms, WebPages and MVC or just a Web API by itself. And you can also self-host Web API in your own applications from Console, Desktop or Service applications. If you're interested in a high level overview on what ASP.NET Web API is and how it fits into the ASP.NET stack you can check out my previous post: Where does ASP.NET Web API fit? In the following article, I'll focus on a practical, by example introduction to ASP.NET Web API. All the code discussed in this article is available in GitHub: https://github.com/RickStrahl/AspNetWebApiArticle [republished from my Code Magazine Article and updated for RTM release of ASP.NET Web API] Getting Started To start I’ll create a new empty ASP.NET application to demonstrate that Web API can work with any kind of ASP.NET project. Although you can create a new project based on the ASP.NET MVC/Web API template to quickly get up and running, I’ll take you through the manual setup process, because one common use case is to add Web API functionality to an existing ASP.NET application. This process describes the steps needed to hook up Web API to any ASP.NET 4.0 application. Start by creating an ASP.NET Empty Project. Then create a new folder in the project called Controllers. Add a Web API Controller Class Once you have any kind of ASP.NET project open, you can add a Web API Controller class to it. Web API Controllers are very similar to MVC Controller classes, but they work in any kind of project. Add a new item to this folder by using the Add New Item option in Visual Studio and choose Web API Controller Class, as shown in Figure 1. Figure 1: This is how you create a new Controller Class in Visual Studio   Make sure that the name of the controller class includes Controller at the end of it, which is required in order for Web API routing to find it. Here, the name for the class is AlbumApiController. For this example, I’ll use a Music Album model to demonstrate basic behavior of Web API. The model consists of albums and related songs where an album has properties like Name, Artist and YearReleased and a list of songs with a SongName and SongLength as well as an AlbumId that links it to the album. You can find the code for the model (and the rest of these samples) on Github. To add the file manually, create a new folder called Model, and add a new class Album.cs and copy the code into it. There’s a static AlbumData class with a static CreateSampleAlbumData() method that creates a short list of albums on a static .Current that I’ll use for the examples. Before we look at what goes into the controller class though, let’s hook up routing so we can access this new controller. Hooking up Routing in Global.asax To start, I need to perform the one required configuration task in order for Web API to work: I need to configure routing to the controller. Like MVC, Web API uses routing to provide clean, extension-less URLs to controller methods. Using an extension method to ASP.NET’s static RouteTable class, you can use the MapHttpRoute() (in the System.Web.Http namespace) method to hook-up the routing during Application_Start in global.asax.cs shown in Listing 1.using System; using System.Web.Routing; using System.Web.Http; namespace AspNetWebApi { public class Global : System.Web.HttpApplication { protected void Application_Start(object sender, EventArgs e) { RouteTable.Routes.MapHttpRoute( name: "AlbumVerbs", routeTemplate: "albums/{title}", defaults: new { symbol = RouteParameter.Optional, controller="AlbumApi" } ); } } } This route configures Web API to direct URLs that start with an albums folder to the AlbumApiController class. Routing in ASP.NET is used to create extensionless URLs and allows you to map segments of the URL to specific Route Value parameters. A route parameter, with a name inside curly brackets like {name}, is mapped to parameters on the controller methods. Route parameters can be optional, and there are two special route parameters – controller and action – that determine the controller to call and the method to activate respectively. HTTP Verb Routing Routing in Web API can route requests by HTTP Verb in addition to standard {controller},{action} routing. For the first examples, I use HTTP Verb routing, as shown Listing 1. Notice that the route I’ve defined does not include an {action} route value or action value in the defaults. Rather, Web API can use the HTTP Verb in this route to determine the method to call the controller, and a GET request maps to any method that starts with Get. So methods called Get() or GetAlbums() are matched by a GET request and a POST request maps to a Post() or PostAlbum(). Web API matches a method by name and parameter signature to match a route, query string or POST values. In lieu of the method name, the [HttpGet,HttpPost,HttpPut,HttpDelete, etc] attributes can also be used to designate the accepted verbs explicitly if you don’t want to follow the verb naming conventions. Although HTTP Verb routing is a good practice for REST style resource APIs, it’s not required and you can still use more traditional routes with an explicit {action} route parameter. When {action} is supplied, the HTTP verb routing is ignored. I’ll talk more about alternate routes later. When you’re finished with initial creation of files, your project should look like Figure 2.   Figure 2: The initial project has the new API Controller Album model   Creating a small Album Model Now it’s time to create some controller methods to serve data. For these examples, I’ll use a very simple Album and Songs model to play with, as shown in Listing 2. public class Song { public string AlbumId { get; set; } [Required, StringLength(80)] public string SongName { get; set; } [StringLength(5)] public string SongLength { get; set; } } public class Album { public string Id { get; set; } [Required, StringLength(80)] public string AlbumName { get; set; } [StringLength(80)] public string Artist { get; set; } public int YearReleased { get; set; } public DateTime Entered { get; set; } [StringLength(150)] public string AlbumImageUrl { get; set; } [StringLength(200)] public string AmazonUrl { get; set; } public virtual List<Song> Songs { get; set; } public Album() { Songs = new List<Song>(); Entered = DateTime.Now; // Poor man's unique Id off GUID hash Id = Guid.NewGuid().GetHashCode().ToString("x"); } public void AddSong(string songName, string songLength = null) { this.Songs.Add(new Song() { AlbumId = this.Id, SongName = songName, SongLength = songLength }); } } Once the model has been created, I also added an AlbumData class that generates some static data in memory that is loaded onto a static .Current member. The signature of this class looks like this and that's what I'll access to retrieve the base data:public static class AlbumData { // sample data - static list public static List<Album> Current = CreateSampleAlbumData(); /// <summary> /// Create some sample data /// </summary> /// <returns></returns> public static List<Album> CreateSampleAlbumData() { … }} You can check out the full code for the data generation online. Creating an AlbumApiController Web API shares many concepts of ASP.NET MVC, and the implementation of your API logic is done by implementing a subclass of the System.Web.Http.ApiController class. Each public method in the implemented controller is a potential endpoint for the HTTP API, as long as a matching route can be found to invoke it. The class name you create should end in Controller, which is how Web API matches the controller route value to figure out which class to invoke. Inside the controller you can implement methods that take standard .NET input parameters and return .NET values as results. Web API’s binding tries to match POST data, route values, form values or query string values to your parameters. Because the controller is configured for HTTP Verb based routing (no {action} parameter in the route), any methods that start with Getxxxx() are called by an HTTP GET operation. You can have multiple methods that match each HTTP Verb as long as the parameter signatures are different and can be matched by Web API. In Listing 3, I create an AlbumApiController with two methods to retrieve a list of albums and a single album by its title .public class AlbumApiController : ApiController { public IEnumerable<Album> GetAlbums() { var albums = AlbumData.Current.OrderBy(alb => alb.Artist); return albums; } public Album GetAlbum(string title) { var album = AlbumData.Current .SingleOrDefault(alb => alb.AlbumName.Contains(title)); return album; }} To access the first two requests, you can use the following URLs in your browser: http://localhost/aspnetWebApi/albumshttp://localhost/aspnetWebApi/albums/Dirty%20Deeds Note that you’re not specifying the actions of GetAlbum or GetAlbums in these URLs. Instead Web API’s routing uses HTTP GET verb to route to these methods that start with Getxxx() with the first mapping to the parameterless GetAlbums() method and the latter to the GetAlbum(title) method that receives the title parameter mapped as optional in the route. Content Negotiation When you access any of the URLs above from a browser, you get either an XML or JSON result returned back. The album list result for Chrome 17 and Internet Explorer 9 is shown Figure 3. Figure 3: Web API responses can vary depending on the browser used, demonstrating Content Negotiation in action as these two browsers send different HTTP Accept headers.   Notice that the results are not the same: Chrome returns an XML response and IE9 returns a JSON response. Whoa, what’s going on here? Shouldn’t we see the same result in both browsers? Actually, no. Web API determines what type of content to return based on Accept headers. HTTP clients, like browsers, use Accept headers to specify what kind of content they’d like to see returned. Browsers generally ask for HTML first, followed by a few additional content types. Chrome (and most other major browsers) ask for: Accept: text/html, application/xhtml+xml,application/xml; q=0.9,*/*;q=0.8 IE9 asks for: Accept: text/html, application/xhtml+xml, */* Note that Chrome’s Accept header includes application/xml, which Web API finds in its list of supported media types and returns an XML response. IE9 does not include an Accept header type that works on Web API by default, and so it returns the default format, which is JSON. This is an important and very useful feature that was missing from any previous Microsoft REST tools: Web API automatically switches output formats based on HTTP Accept headers. Nowhere in the server code above do you have to explicitly specify the output format. Rather, Web API determines what format the client is requesting based on the Accept headers and automatically returns the result based on the available formatters. This means that a single method can handle both XML and JSON results.. Using this simple approach makes it very easy to create a single controller method that can return JSON, XML, ATOM or even OData feeds by providing the appropriate Accept header from the client. By default you don’t have to worry about the output format in your code. Note that you can still specify an explicit output format if you choose, either globally by overriding the installed formatters, or individually by returning a lower level HttpResponseMessage instance and setting the formatter explicitly. More on that in a minute. Along the same lines, any content sent to the server via POST/PUT is parsed by Web API based on the HTTP Content-type of the data sent. The same formats allowed for output are also allowed on input. Again, you don’t have to do anything in your code – Web API automatically performs the deserialization from the content. Accessing Web API JSON Data with jQuery A very common scenario for Web API endpoints is to retrieve data for AJAX calls from the Web browser. Because JSON is the default format for Web API, it’s easy to access data from the server using jQuery and its getJSON() method. This example receives the albums array from GetAlbums() and databinds it into the page using knockout.js.$.getJSON("albums/", function (albums) { // make knockout template visible $(".album").show(); // create view object and attach array var view = { albums: albums }; ko.applyBindings(view); }); Figure 4 shows this and the next example’s HTML output. You can check out the complete HTML and script code at http://goo.gl/Ix33C (.html) and http://goo.gl/tETlg (.js). Figu Figure 4: The Album Display sample uses JSON data loaded from Web API.   The result from the getJSON() call is a JavaScript object of the server result, which comes back as a JavaScript array. In the code, I use knockout.js to bind this array into the UI, which as you can see, requires very little code, instead using knockout’s data-bind attributes to bind server data to the UI. Of course, this is just one way to use the data – it’s entirely up to you to decide what to do with the data in your client code. Along the same lines, I can retrieve a single album to display when the user clicks on an album. The response returns the album information and a child array with all the songs. The code to do this is very similar to the last example where we pulled the albums array:$(".albumlink").live("click", function () { var id = $(this).data("id"); // title $.getJSON("albums/" + id, function (album) { ko.applyBindings(album, $("#divAlbumDialog")[0]); $("#divAlbumDialog").show(); }); }); Here the URL looks like this: /albums/Dirty%20Deeds, where the title is the ID captured from the clicked element’s data ID attribute. Explicitly Overriding Output Format When Web API automatically converts output using content negotiation, it does so by matching Accept header media types to the GlobalConfiguration.Configuration.Formatters and the SupportedMediaTypes of each individual formatter. You can add and remove formatters to globally affect what formats are available and it’s easy to create and plug in custom formatters.The example project includes a JSONP formatter that can be plugged in to provide JSONP support for requests that have a callback= querystring parameter. Adding, removing or replacing formatters is a global option you can use to manipulate content. It’s beyond the scope of this introduction to show how it works, but you can review the sample code or check out my blog entry on the subject (http://goo.gl/UAzaR). If automatic processing is not desirable in a particular Controller method, you can override the response output explicitly by returning an HttpResponseMessage instance. HttpResponseMessage is similar to ActionResult in ASP.NET MVC in that it’s a common way to return an abstract result message that contains content. HttpResponseMessage s parsed by the Web API framework using standard interfaces to retrieve the response data, status code, headers and so on[MS2] . Web API turns every response – including those Controller methods that return static results – into HttpResponseMessage instances. Explicitly returning an HttpResponseMessage instance gives you full control over the output and lets you mostly bypass WebAPI’s post-processing of the HTTP response on your behalf. HttpResponseMessage allows you to customize the response in great detail. Web API’s attention to detail in the HTTP spec really shows; many HTTP options are exposed as properties and enumerations with detailed IntelliSense comments. Even if you’re new to building REST-based interfaces, the API guides you in the right direction for returning valid responses and response codes. For example, assume that I always want to return JSON from the GetAlbums() controller method and ignore the default media type content negotiation. To do this, I can adjust the output format and headers as shown in Listing 4.public HttpResponseMessage GetAlbums() { var albums = AlbumData.Current.OrderBy(alb => alb.Artist); // Create a new HttpResponse with Json Formatter explicitly var resp = new HttpResponseMessage(HttpStatusCode.OK); resp.Content = new ObjectContent<IEnumerable<Album>>( albums, new JsonMediaTypeFormatter()); // Get Default Formatter based on Content Negotiation //var resp = Request.CreateResponse<IEnumerable<Album>>(HttpStatusCode.OK, albums); resp.Headers.ConnectionClose = true; resp.Headers.CacheControl = new CacheControlHeaderValue(); resp.Headers.CacheControl.Public = true; return resp; } This example returns the same IEnumerable<Album> value, but it wraps the response into an HttpResponseMessage so you can control the entire HTTP message result including the headers, formatter and status code. In Listing 4, I explicitly specify the formatter using the JsonMediaTypeFormatter to always force the content to JSON.  If you prefer to use the default content negotiation with HttpResponseMessage results, you can create the Response instance using the Request.CreateResponse method:var resp = Request.CreateResponse<IEnumerable<Album>>(HttpStatusCode.OK, albums); This provides you an HttpResponse object that's pre-configured with the default formatter based on Content Negotiation. Once you have an HttpResponse object you can easily control most HTTP aspects on this object. What's sweet here is that there are many more detailed properties on HttpResponse than the core ASP.NET Response object, with most options being explicitly configurable with enumerations that make it easy to pick the right headers and response codes from a list of valid codes. It makes HTTP features available much more discoverable even for non-hardcore REST/HTTP geeks. Non-Serialized Results The output returned doesn’t have to be a serialized value but can also be raw data, like strings, binary data or streams. You can use the HttpResponseMessage.Content object to set a number of common Content classes. Listing 5 shows how to return a binary image using the ByteArrayContent class from a Controller method. [HttpGet] public HttpResponseMessage AlbumArt(string title) { var album = AlbumData.Current.FirstOrDefault(abl => abl.AlbumName.StartsWith(title)); if (album == null) { var resp = Request.CreateResponse<ApiMessageError>( HttpStatusCode.NotFound, new ApiMessageError("Album not found")); return resp; } // kinda silly - we would normally serve this directly // but hey - it's a demo. var http = new WebClient(); var imageData = http.DownloadData(album.AlbumImageUrl); // create response and return var result = new HttpResponseMessage(HttpStatusCode.OK); result.Content = new ByteArrayContent(imageData); result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg"); return result; } The image retrieval from Amazon is contrived, but it shows how to return binary data using ByteArrayContent. It also demonstrates that you can easily return multiple types of content from a single controller method, which is actually quite common. If an error occurs - such as a resource can’t be found or a validation error – you can return an error response to the client that’s very specific to the error. In GetAlbumArt(), if the album can’t be found, we want to return a 404 Not Found status (and realistically no error, as it’s an image). Note that if you are not using HTTP Verb-based routing or not accessing a method that starts with Get/Post etc., you have to specify one or more HTTP Verb attributes on the method explicitly. Here, I used the [HttpGet] attribute to serve the image. Another option to handle the error could be to return a fixed placeholder image if no album could be matched or the album doesn’t have an image. When returning an error code, you can also return a strongly typed response to the client. For example, you can set the 404 status code and also return a custom error object (ApiMessageError is a class I defined) like this:return Request.CreateResponse<ApiMessageError>( HttpStatusCode.NotFound, new ApiMessageError("Album not found") );   If the album can be found, the image will be returned. The image is downloaded into a byte[] array, and then assigned to the result’s Content property. I created a new ByteArrayContent instance and assigned the image’s bytes and the content type so that it displays properly in the browser. There are other content classes available: StringContent, StreamContent, ByteArrayContent, MultipartContent, and ObjectContent are at your disposal to return just about any kind of content. You can create your own Content classes if you frequently return custom types and handle the default formatter assignments that should be used to send the data out . Although HttpResponseMessage results require more code than returning a plain .NET value from a method, it allows much more control over the actual HTTP processing than automatic processing. It also makes it much easier to test your controller methods as you get a response object that you can check for specific status codes and output messages rather than just a result value. Routing Again Ok, let’s get back to the image example. Using the original routing we have setup using HTTP Verb routing there's no good way to serve the image. In order to return my album art image I’d like to use a URL like this: http://localhost/aspnetWebApi/albums/Dirty%20Deeds/image In order to create a URL like this, I have to create a new Controller because my earlier routes pointed to the AlbumApiController using HTTP Verb routing. HTTP Verb based routing is great for representing a single set of resources such as albums. You can map operations like add, delete, update and read easily using HTTP Verbs. But you cannot mix action based routing into a an HTTP Verb routing controller - you can only map HTTP Verbs and each method has to be unique based on parameter signature. You can't have multiple GET operations to methods with the same signature. So GetImage(string id) and GetAlbum(string title) are in conflict in an HTTP GET routing scenario. In fact, I was unable to make the above Image URL work with any combination of HTTP Verb plus Custom routing using the single Albums controller. There are number of ways around this, but all involve additional controllers.  Personally, I think it’s easier to use explicit Action routing and then add custom routes if you need to simplify your URLs further. So in order to accommodate some of the other examples, I created another controller – AlbumRpcApiController – to handle all requests that are explicitly routed via actions (/albums/rpc/AlbumArt) or are custom routed with explicit routes defined in the HttpConfiguration. I added the AlbumArt() method to this new AlbumRpcApiController class. For the image URL to work with the new AlbumRpcApiController, you need a custom route placed before the default route from Listing 1.RouteTable.Routes.MapHttpRoute( name: "AlbumRpcApiAction", routeTemplate: "albums/rpc/{action}/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumRpcApi", action = "GetAblums" } ); Now I can use either of the following URLs to access the image: Custom route: (/albums/rpc/{title}/image)http://localhost/aspnetWebApi/albums/PowerAge/image Action route: (/albums/rpc/action/{title})http://localhost/aspnetWebAPI/albums/rpc/albumart/PowerAge Sending Data to the Server To send data to the server and add a new album, you can use an HTTP POST operation. Since I’m using HTTP Verb-based routing in the original AlbumApiController, I can implement a method called PostAlbum()to accept a new album from the client. Listing 6 shows the Web API code to add a new album.public HttpResponseMessage PostAlbum(Album album) { if (!this.ModelState.IsValid) { // my custom error class var error = new ApiMessageError() { message = "Model is invalid" }; // add errors into our client error model for client foreach (var prop in ModelState.Values) { var modelError = prop.Errors.FirstOrDefault(); if (!string.IsNullOrEmpty(modelError.ErrorMessage)) error.errors.Add(modelError.ErrorMessage); else error.errors.Add(modelError.Exception.Message); } return Request.CreateResponse<ApiMessageError>(HttpStatusCode.Conflict, error); } // update song id which isn't provided foreach (var song in album.Songs) song.AlbumId = album.Id; // see if album exists already var matchedAlbum = AlbumData.Current .SingleOrDefault(alb => alb.Id == album.Id || alb.AlbumName == album.AlbumName); if (matchedAlbum == null) AlbumData.Current.Add(album); else matchedAlbum = album; // return a string to show that the value got here var resp = Request.CreateResponse(HttpStatusCode.OK, string.Empty); resp.Content = new StringContent(album.AlbumName + " " + album.Entered.ToString(), Encoding.UTF8, "text/plain"); return resp; } The PostAlbum() method receives an album parameter, which is automatically deserialized from the POST buffer the client sent. The data passed from the client can be either XML or JSON. Web API automatically figures out what format it needs to deserialize based on the content type and binds the content to the album object. Web API uses model binding to bind the request content to the parameter(s) of controller methods. Like MVC you can check the model by looking at ModelState.IsValid. If it’s not valid, you can run through the ModelState.Values collection and check each binding for errors. Here I collect the error messages into a string array that gets passed back to the client via the result ApiErrorMessage object. When a binding error occurs, you’ll want to return an HTTP error response and it’s best to do that with an HttpResponseMessage result. In Listing 6, I used a custom error class that holds a message and an array of detailed error messages for each binding error. I used this object as the content to return to the client along with my Conflict HTTP Status Code response. If binding succeeds, the example returns a string with the name and date entered to demonstrate that you captured the data. Normally, a method like this should return a Boolean or no response at all (HttpStatusCode.NoConent). The sample uses a simple static list to hold albums, so once you’ve added the album using the Post operation, you can hit the /albums/ URL to see that the new album was added. The client jQuery code to call the POST operation from the client with jQuery is shown in Listing 7. var id = new Date().getTime().toString(); var album = { "Id": id, "AlbumName": "Power Age", "Artist": "AC/DC", "YearReleased": 1977, "Entered": "2002-03-11T18:24:43.5580794-10:00", "AlbumImageUrl": http://ecx.images-amazon.com/images/…, "AmazonUrl": http://www.amazon.com/…, "Songs": [ { "SongName": "Rock 'n Roll Damnation", "SongLength": 3.12}, { "SongName": "Downpayment Blues", "SongLength": 4.22 }, { "SongName": "Riff Raff", "SongLength": 2.42 } ] } $.ajax( { url: "albums/", type: "POST", contentType: "application/json", data: JSON.stringify(album), processData: false, beforeSend: function (xhr) { // not required since JSON is default output xhr.setRequestHeader("Accept", "application/json"); }, success: function (result) { // reload list of albums page.loadAlbums(); }, error: function (xhr, status, p3, p4) { var err = "Error"; if (xhr.responseText && xhr.responseText[0] == "{") err = JSON.parse(xhr.responseText).message; alert(err); } }); The code in Listing 7 creates an album object in JavaScript to match the structure of the .NET Album class. This object is passed to the $.ajax() function to send to the server as POST. The data is turned into JSON and the content type set to application/json so that the server knows what to convert when deserializing in the Album instance. The jQuery code hooks up success and failure events. Success returns the result data, which is a string that’s echoed back with an alert box. If an error occurs, jQuery returns the XHR instance and status code. You can check the XHR to see if a JSON object is embedded and if it is, you can extract it by de-serializing it and accessing the .message property. REST standards suggest that updates to existing resources should use PUT operations. REST standards aside, I’m not a big fan of separating out inserts and updates so I tend to have a single method that handles both. But if you want to follow REST suggestions, you can create a PUT method that handles updates by forwarding the PUT operation to the POST method:public HttpResponseMessage PutAlbum(Album album) { return PostAlbum(album); } To make the corresponding $.ajax() call, all you have to change from Listing 7 is the type: from POST to PUT. Model Binding with UrlEncoded POST Variables In the example in Listing 7 I used JSON objects to post a serialized object to a server method that accepted an strongly typed object with the same structure, which is a common way to send data to the server. However, Web API supports a number of different ways that data can be received by server methods. For example, another common way is to use plain UrlEncoded POST  values to send to the server. Web API supports Model Binding that works similar (but not the same) as MVC's model binding where POST variables are mapped to properties of object parameters of the target method. This is actually quite common for AJAX calls that want to avoid serialization and the potential requirement of a JSON parser on older browsers. For example, using jQUery you might use the $.post() method to send a new album to the server (albeit one without songs) using code like the following:$.post("albums/",{AlbumName: "Dirty Deeds", YearReleased: 1976 … },albumPostCallback); Although the code looks very similar to the client code we used before passing JSON, here the data passed is URL encoded values (AlbumName=Dirty+Deeds&YearReleased=1976 etc.). Web API then takes this POST data and maps each of the POST values to the properties of the Album object in the method's parameter. Although the client code is different the server can both handle the JSON object, or the UrlEncoded POST values. Dynamic Access to POST Data There are also a few options available to dynamically access POST data, if you know what type of data you're dealing with. If you have POST UrlEncoded values, you can dynamically using a FormsDataCollection:[HttpPost] public string PostAlbum(FormDataCollection form) { return string.Format("{0} - released {1}", form.Get("AlbumName"),form.Get("RearReleased")); } The FormDataCollection is a very simple object, that essentially provides the same functionality as Request.Form[] in ASP.NET. Request.Form[] still works if you're running hosted in an ASP.NET application. However as a general rule, while ASP.NET's functionality is always available when running Web API hosted inside of an  ASP.NET application, using the built in classes specific to Web API makes it possible to run Web API applications in a self hosted environment outside of ASP.NET. If your client is sending JSON to your server, and you don't want to map the JSON to a strongly typed object because you only want to retrieve a few simple values, you can also accept a JObject parameter in your API methods:[HttpPost] public string PostAlbum(JObject jsonData) { dynamic json = jsonData; JObject jalbum = json.Album; JObject juser = json.User; string token = json.UserToken; var album = jalbum.ToObject<Album>(); var user = juser.ToObject<User>(); return String.Format("{0} {1} {2}", album.AlbumName, user.Name, token); } There quite a few options available to you to receive data with Web API, which gives you more choices for the right tool for the job. Unfortunately one shortcoming of Web API is that POST data is always mapped to a single parameter. This means you can't pass multiple POST parameters to methods that receive POST data. It's possible to accept multiple parameters, but only one can map to the POST content - the others have to come from the query string or route values. I have a couple of Blog POSTs that explain what works and what doesn't here: Passing multiple POST parameters to Web API Controller Methods Mapping UrlEncoded POST Values in ASP.NET Web API   Handling Delete Operations Finally, to round out the server API code of the album example we've been discussin, here’s the DELETE verb controller method that allows removal of an album by its title:public HttpResponseMessage DeleteAlbum(string title) { var matchedAlbum = AlbumData.Current.Where(alb => alb.AlbumName == title) .SingleOrDefault(); if (matchedAlbum == null) return new HttpResponseMessage(HttpStatusCode.NotFound); AlbumData.Current.Remove(matchedAlbum); return new HttpResponseMessage(HttpStatusCode.NoContent); } To call this action method using jQuery, you can use:$(".removeimage").live("click", function () { var $el = $(this).parent(".album"); var txt = $el.find("a").text(); $.ajax({ url: "albums/" + encodeURIComponent(txt), type: "Delete", success: function (result) { $el.fadeOut().remove(); }, error: jqError }); }   Note the use of the DELETE verb in the $.ajax() call, which routes to DeleteAlbum on the server. DELETE is a non-content operation, so you supply a resource ID (the title) via route value or the querystring. Routing Conflicts In all requests with the exception of the AlbumArt image example shown so far, I used HTTP Verb routing that I set up in Listing 1. HTTP Verb Routing is a recommendation that is in line with typical REST access to HTTP resources. However, it takes quite a bit of effort to create REST-compliant API implementations based only on HTTP Verb routing only. You saw one example that didn’t really fit – the return of an image where I created a custom route albums/{title}/image that required creation of a second controller and a custom route to work. HTTP Verb routing to a controller does not mix with custom or action routing to the same controller because of the limited mapping of HTTP verbs imposed by HTTP Verb routing. To understand some of the problems with verb routing, let’s look at another example. Let’s say you create a GetSortableAlbums() method like this and add it to the original AlbumApiController accessed via HTTP Verb routing:[HttpGet] public IQueryable<Album> SortableAlbums() { var albums = AlbumData.Current; // generally should be done only on actual queryable results (EF etc.) // Done here because we're running with a static list but otherwise might be slow return albums.AsQueryable(); } If you compile this code and try to now access the /albums/ link, you get an error: Multiple Actions were found that match the request. HTTP Verb routing only allows access to one GET operation per parameter/route value match. If more than one method exists with the same parameter signature, it doesn’t work. As I mentioned earlier for the image display, the only solution to get this method to work is to throw it into another controller. Because I already set up the AlbumRpcApiController I can add the method there. First, I should rename the method to SortableAlbums() so I’m not using a Get prefix for the method. This also makes the action parameter look cleaner in the URL - it looks less like a method and more like a noun. I can then create a new route that handles direct-action mapping:RouteTable.Routes.MapHttpRoute( name: "AlbumRpcApiAction", routeTemplate: "albums/rpc/{action}/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumRpcApi", action = "GetAblums" } ); As I am explicitly adding a route segment – rpc – into the route template, I can now reference explicit methods in the Web API controller using URLs like this: http://localhost/AspNetWebApi/rpc/SortableAlbums Error Handling I’ve already done some minimal error handling in the examples. For example in Listing 6, I detected some known-error scenarios like model validation failing or a resource not being found and returning an appropriate HttpResponseMessage result. But what happens if your code just blows up or causes an exception? If you have a controller method, like this:[HttpGet] public void ThrowException() { throw new UnauthorizedAccessException("Unauthorized Access Sucka"); } You can call it with this: http://localhost/AspNetWebApi/albums/rpc/ThrowException The default exception handling displays a 500-status response with the serialized exception on the local computer only. When you connect from a remote computer, Web API throws back a 500  HTTP Error with no data returned (IIS then adds its HTML error page). The behavior is configurable in the GlobalConfiguration:GlobalConfiguration .Configuration .IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Never; If you want more control over your error responses sent from code, you can throw explicit error responses yourself using HttpResponseException. When you throw an HttpResponseException the response parameter is used to generate the output for the Controller action. [HttpGet] public void ThrowError() { var resp = Request.CreateResponse<ApiMessageError>( HttpStatusCode.BadRequest, new ApiMessageError("Your code stinks!")); throw new HttpResponseException(resp); } Throwing an HttpResponseException stops the processing of the controller method and immediately returns the response you passed to the exception. Unlike other Exceptions fired inside of WebAPI, HttpResponseException bypasses the Exception Filters installed and instead just outputs the response you provide. In this case, the serialized ApiMessageError result string is returned in the default serialization format – XML or JSON. You can pass any content to HttpResponseMessage, which includes creating your own exception objects and consistently returning error messages to the client. Here’s a small helper method on the controller that you might use to send exception info back to the client consistently:private void ThrowSafeException(string message, HttpStatusCode statusCode = HttpStatusCode.BadRequest) { var errResponse = Request.CreateResponse<ApiMessageError>(statusCode, new ApiMessageError() { message = message }); throw new HttpResponseException(errResponse); } You can then use it to output any captured errors from code:[HttpGet] public void ThrowErrorSafe() { try { List<string> list = null; list.Add("Rick"); } catch (Exception ex) { ThrowSafeException(ex.Message); } }   Exception Filters Another more global solution is to create an Exception Filter. Filters in Web API provide the ability to pre- and post-process controller method operations. An exception filter looks at all exceptions fired and then optionally creates an HttpResponseMessage result. Listing 8 shows an example of a basic Exception filter implementation.public class UnhandledExceptionFilter : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { HttpStatusCode status = HttpStatusCode.InternalServerError; var exType = context.Exception.GetType(); if (exType == typeof(UnauthorizedAccessException)) status = HttpStatusCode.Unauthorized; else if (exType == typeof(ArgumentException)) status = HttpStatusCode.NotFound; var apiError = new ApiMessageError() { message = context.Exception.Message }; // create a new response and attach our ApiError object // which now gets returned on ANY exception result var errorResponse = context.Request.CreateResponse<ApiMessageError>(status, apiError); context.Response = errorResponse; base.OnException(context); } } Exception Filter Attributes can be assigned to an ApiController class like this:[UnhandledExceptionFilter] public class AlbumRpcApiController : ApiController or you can globally assign it to all controllers by adding it to the HTTP Configuration's Filters collection:GlobalConfiguration.Configuration.Filters.Add(new UnhandledExceptionFilter()); The latter is a great way to get global error trapping so that all errors (short of hard IIS errors and explicit HttpResponseException errors) return a valid error response that includes error information in the form of a known-error object. Using a filter like this allows you to throw an exception as you normally would and have your filter create a response in the appropriate output format that the client expects. For example, an AJAX application can on failure expect to see a JSON error result that corresponds to the real error that occurred rather than a 500 error along with HTML error page that IIS throws up. You can even create some custom exceptions so you can differentiate your own exceptions from unhandled system exceptions - you often don't want to display error information from 'unknown' exceptions as they may contain sensitive system information or info that's not generally useful to users of your application/site. This is just one example of how ASP.NET Web API is configurable and extensible. Exception filters are just one example of how you can plug-in into the Web API request flow to modify output. Many more hooks exist and I’ll take a closer look at extensibility in Part 2 of this article in the future. Summary Web API is a big improvement over previous Microsoft REST and AJAX toolkits. The key features to its usefulness are its ease of use with simple controller based logic, familiar MVC-style routing, low configuration impact, extensibility at all levels and tight attention to exposing and making HTTP semantics easily discoverable and easy to use. Although none of the concepts used in Web API are new or radical, Web API combines the best of previous platforms into a single framework that’s highly functional, easy to work with, and extensible to boot. I think that Microsoft has hit a home run with Web API. Related Resources Where does ASP.NET Web API fit? Sample Source Code on GitHub Passing multiple POST parameters to Web API Controller Methods Mapping UrlEncoded POST Values in ASP.NET Web API Creating a JSONP Formatter for ASP.NET Web API Removing the XML Formatter from ASP.NET Web API Applications© 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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