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  • Why are SIP calls via my server silent?

    - by Archcode
    I have FreeSWITCH SIP server up and running. It has public IP and sits behind 1-to-1 NAT (it's Amazon EC2 instance actually). I can connect to it, make a call to other endpoint (namely, my android device to my pc and vice versa) and signals are send with no problems (call, answer, hangup, etc). Unfortunately, and what drives me crazy, that's all: no audio gets through, no video either. Server does not throw errors, it reports many retransmission though, looks like this: switch_rtp.c:915 [ zrtp engine]: WARNING! HELLO Max retransmissions count reached (20 retries). ID=15 Codecs are set up correctly (same config worked locally on my LAN). NAT/firewall on client side may be a problem, signals do get through (perhaps due to fixed port, data streaming runs on random one, that is currently my best bet). STUN/TURN/ICE setting on client seem to have no effect. Endpoints sit behind symmetric NAT. On server there are no iptables rules, security group is set as suggested there: http://wiki.freeswitch.org/wiki/Firewall Help, please. How to make it work or at least diagnose what's wrong?

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  • moving files and directories between two machine, via a third, preserving permissions and usernames

    - by Jarmund
    The situation is as follows: Machine A has a file repository accessible via rsync Machine B needs the above mentioned files with all permissions and ownerships intact (including groups etc) Machine C has access to both A and B, but has a completely different set of users. Normally, i would just rsync everything over, directly between A and B, but due to severely limited bandwidth at the moment, i need something different, as rsync times out after building the list of the 430 files (49Mb uncompressed... can be compressed down to ~7Mb). What i've tried so far: rsync everything over from A to C, tar it, copy the tarball over, and then untar it, however, this messes up the ownership and/or the permissions. To rsync it from A to C, i run this command: rsync --numeric-ids --password-file=/root/rsync_pwd_file -oaPvu rsync://[email protected]/portal_2/ ./portal_2/ ...and from the looks of things, they do end up on C with the correct ownerships/permissions/flags/everything (not 100% sure, though.. are there any more switches i can throw in there? did i miss something?) copying the tarball over is simple enough (slow as a one-legged turtle due to the bandwidth, but it checksums out alright) What i'm unsure of is the flags and switches for creating and extracting the tarball, so could someone please provide the full commands for creating a tarball from /root/portal_2 on machine C (with everything intact) and extracting the tarball into /var/ex/portal_2 on machine B? ? Also, are there any other approaches worth mentioning that could allow me to perform this? I have root access to A and C, whereas i only have rsync access to B. PS: I'm running rsync v2.6.9 on machine B, and unfortunately i do not have the oportunity to upgrade to v3

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  • Slower/cached Linux file system required

    - by Chopper3
    I know it sounds odd but I need a slower or cached filesystem. I have a lot of firewalls that are syslog'ing their data to a pair of Linux VMs which write these files to their 'local' (actually FC SAN attached) ext3-formatted disks and also forward the messages to our Splunk servers. The problem is that the syslog server is writing these syslog messages as hundreds, sometimes thousands, of tiny ~4k writes per second back to our FC SAN - which can handle this workload right now but our FW traffic's going to be growing by at least a factor of 5000% (really) in coming months and that'll be a pain for the SAN, I want to fix the root cause before it's a problem. So I need some help figuring out a way of getting these writes cached or held-off in some way from the 'physical' disks so that the VMs fire off larger, but less frequent, writes - there's no way of avoiding these writes but there's no need for it to do so many tiny ones. I've looked at the various ext3 options, setting noatime and nodiratime but that's not made much of a dent in the problem. Obviously I'm investigating other file systems but thought I'd throw this out in case others have the same problem in the future. Oh and I can't just forward these messages to Splunk, our firewall team insist they're in their original format for diag purposes.

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  • After RAID failure SBS 2008 issues logging in and Exchange store does not mount

    - by Josh R
    today has been one of those days. Yesterday a hard drive in our Dell Poweredge 2900 server failed and the RAID array didn't degrade gracefully, so I called Dell (Server still under warranty) and got an engineer to work though the RAID issues with me. He was a nice guy but didn't do too much. We tried to put the RAID in a state where it was bootable and even though we only lost one disk there are still issues with the server. Once we got the server to boot there was an error message saying that the logonui.exe was corrupted and we needed to run chkdsk. I clicked through the error messages and the login screen never came up. So I power cycled the server and it chkdsk automatically but the login screen didn't appear. I tried safe mode, no difference there either. So the issues I am currently having are: 1) The server boots up, the loading windows screen comes up then it dumps me into a black screen where I can only see my mouse cursor. Ctrl+Esc doesn't work Ctrl+Alt+Del doesn't work 2) Some of the services come up: DHCP, DNS, DFS, and Print come up 3) The exchange information store and transport service don't start - I tried using mmc to connect to services.msc on the computer and start them but they throw an error message of "Can't start because group or dependency failed" Has anyone had a problem like this? Can anyone offer some guidance? Thanks a bunch!

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  • LAMP Stack Version Help -- Is there a website or version tracker source to help suggest the right versions of each part of a platform stack?

    - by Chris Adragna
    Taken singly, it's easy to research versions and compatibility. Version information is readily available on each single part of a platform stack, such as MySQL. You can find out the latest version, stable version, and sometimes even the percentage of people adopting it by version (personally, I like seeing numbers on adoption rates). However, when trying to find the best possible mix of versions, I have a harder time. For example, "if you're using MySQL 5.5, you'll need PHP version XX or higher." It gets even more difficult to mitigate when you throw higher level platforms into the mix such as Drupal, Joomla, etc. I do consider "wizard" like installers to be beneficial, such as the Bitnami installers. However, I always wonder if those solutions cater more to the least common denominator -- be all to many -- and as such, I think I'd be better to install things on my own. Such solutions do seem kind of slow to adopt new versions, slower than necessary, I suspect. Is there a website or tool that consolidates versioning data in order to help a webmaster choose which versions to deploy or which upgrades to install, in consideration of all the other parts of the stack?

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  • Centralized backup method recommendation for SMEs with various OSes

    - by Akinator
    Hi I was wondering what in your opinion is the "best" method for having "everything" backed-up in the following situation. We are a SMEs with 10 computers in total. Three of those computers are MACs The rest are windows (1 vista, 4 win7 and 2 XPs) I'm very open to what the method should be but you should also consider the follwing: Very limited resources Quite "small" bandwidth (4 MBs for all (download) 0.4 MBs (upload, yep, thats it)- though this might get, a little bit better) One of the main thing to back up would be the mails, considerations: All windows computers use outlook, mainly 2003 There is one mac that uses outlook too (for mac of course - not 2011 yet) We also have to backup the files: Not a huge amount Very few very big files Very organizes (by machine) What I would like is to hear your opinions as to which would be the best method (or combination of methods - preferably one of course) considering. We are not sure what do we need and I'm open to suggestions, though an online (cloud based applications) would be great, remember the the bandwidth is unbearable. Last think to consider, it that we would like to do weekly updates (unless the method is very easy of course). Thanks in advance!! I tried to be as specific as possible, but if anything is needed I'll gladly update, please ask for any clarification needed! Please avoid any answers like upgrade all to windows 7 and throw away your macs :) our's may not be an ideal situation, but it is what it is, and right now, it would be impossible for us to change it for a lot of circumstances.

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  • .lnk doesn't open, no errors

    - by MushinNoShin
    I have a shortcut (.LNK) on my desktop to a MS Access database out on a network drive. When I double click that shortcut I get an hour glass for about 10 seconds and then nothing. No errors, no access opening, nothing happens. It appears as if there's not even an MSAccess process running in the background. The file successfully opens from: The Open dialog in Access The commandline "C:\path\to\MSACCESS.EXE C:\path\to\shortcut.lnk" The commandline "C:\path\to\MSACCESS.EXE C:\path\to\whatTheShortcutPointsTo.mdb" The file silently fails to open from: Double clicking the shortcut.lnk Double clicking the mdb file that shortcut.lnk targets At first I thought it had to do with how the link handler operated but the fact that it does the same exact thing when I try to open the mdb directly in explorer makes me think it's an issue with explorer. I've tried restoring, deleting, and recreating the association with the extension. I've tried running MSACCESS.EXE /regserver. I've run out of things to throw at it. In case this is specific to MS Access 2007; I'm trying to use 2007 :)

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  • Could replacing an old hard drive's circuit board make it work again?

    - by oscilatingcretin
    I have a 12-year-old, 10gb Maxtor drive that died on me around 7 years ago, but I have not had the heart to throw it away. When the computer powers on, it whirrs silently as it tries to spin up and then it stops. So, a few years ago, I sent it off for professional data recovery. They were able to retrieve quite a bit from it, but I know there's a bunch more there. It only cost $700, so I just chalked up the lackluster recovery effort to "you get what you pay for" considering that most companies will charge you several thousands of dollars for this kind of data recovery. When they sent the drive back, I couldn't help but plug it back in just to see if maybe they unjammed something in the process of disassembling/reassembling the drive. To my surprise, the drive had a much healthier spin-up sound and actually stayed spinning for several minutes before winding down to a halt. Windows is even able to detect and interact with the drive, but I get I/O errors after so many minutes of waiting for it to mount. Before I start doing stupid stuff with it like dropping it on the ground, freezing it, crapping on it, etc, I decided to buy the exact same model off Ebay so that I could swap the circuit boards as a last-ditch effort. While it's en route, I thought I'd come here to ask if this is even a worthwhile effort and, if even remotely so, what should I know before ripping off the old board and slapping on the new?

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  • Re-packaging commercial software into RPM packages

    - by gac
    The situation is this - I have a small CentOS 5 "cluster" (currently 7 machines, but potential for more) which run a commercially available software package that's distributed essentially in tarball format (it's actually a zip file with a mixture of Windows/Linux binaries and an installation shell script with no potential for automation). I'd like to re-package this somehow into an RPM package (ideally that I can throw onto a self-hosted yum repository) in order to keep these "cluster" machines both up to date and consistent. I could do 7 manual installations, but there's scope for error. As I understand it, I'll need to accomplish the following tasks: add a non-privileged user to the target system for running the daemon without unnecessary root privileges package the binary files themselves up from the final installation location on a separate build machine (probably under /opt/package for sanity's sake). No source is available. add a firewall hole in order for the end-users to be able to communicate with the "cluster" nodes add a cron task which can start the daemon on @reboot I'm coming up with plenty of good packaging resources so far, but all are based on the traditional method (i.e. if I were the vendor packaging up my source files), rather than re-packaging a ton of binary files from an already-installed instance of the application, which is the only option available to me. Anyone have any good resources they can share for achieving this goal? Thanks!

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  • Developing high-performance and scalable zend framework website

    - by Daniel
    We are going to develop an ads website like http://www.gumtree.com/ (it will not be like this one but just to give you an ideea) and we are having some issues regarding performance and scalability. We are planning on using Zend Framework for this project but this is all that I'm sure off at this point. I don't think a classic approch like Zend Framework (PHP) + MySQL + Memcache + jQuery (and I would throw Doctrine 2 in there to) will fix result in a high-performance application. I was thinking on making this a RESTful application (with Zend Framework) + NGINX (or maybe MongoDB) + Memcache (or eAccelerator -- I understand this will create problems with scalability on multiple servers) + jQuery, a CDN for static content, a server for images and a scalable server for the requests and the rest. My questions are: - What do you think about my approch? - What solutions would you recommand in terms of servers approch (MySQL, NGINX, MongoDB or pgsql) for a scalable application expected to have a lot of traffic using PHP?...I would be interested in your approch. Note: I'm a Zend Framework developer and don't have to much experience with the servers part (to determin what would be best solution for my scalable application)

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  • Input/output error reading USB backup drive on CentOS 6.4

    - by Kev
    I'm suddenly seeing some strange behaviour on our USB backup drive that doesn't make sense to me: (2013-10-21 14:58:23 [root@newdc /]$ cd /mnt/backup/ (2013-10-21 14:59:03 [root@newdc backup]$ ls -la ls: reading directory .: Input/output error total 0 (2013-10-21 14:59:05 [root@newdc backup]$ df -h /mnt/backup Filesystem Size Used Avail Use% Mounted on /dev/sda1 917G 843G 28G 97% /mnt/backup How is it possible for the OS to know how much is in use, but I can't ls any of it as root? Or more to the point, what problem does this indicate? /var/log/messages said this: Oct 21 14:57:54 g5 kernel: EXT4-fs error (device sda1): ext4_journal_start_sb: Detected aborted journal Oct 21 14:57:54 g5 kernel: EXT4-fs (sda1): Remounting filesystem read-only But...read-only is something different than 'throw an io error'... After unmounting to try fsck on it, I had someone on-site look at it, and the drive was not spun up, and had a slow-flashing light, which I believe means it was in a power-suspend mode. So I had them unplug and replug the USB cable, and now (before remounting) it says: fsck from util-linux-ng 2.17.2 e2fsck 1.41.12 (17-May-2010) /dev/sda1: clean, 2805106/61046784 files, 181934167/244182016 blocks I then mount it and now ls works and df reports: Filesystem Size Used Avail Use% Mounted on /dev/sda1 917G 680G 191G 79% /mnt/backup What would cause it to go into such a state without being asked to? Why all the weird behaviour, and now it appears to not be corrupt?

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  • When using software RAID and LVM on Linux, which IO scheduler and readahead settings are honored?

    - by andrew311
    In the case of multiple layers (physical drives - md - dm - lvm), how do the schedulers, readahead settings, and other disk settings interact? Imagine you have several disks (/dev/sda - /dev/sdd) all part of a software RAID device (/dev/md0) created with mdadm. Each device (including physical disks and /dev/md0) has its own setting for IO scheduler (changed like so) and readahead (changed using blockdev). When you throw in things like dm (crypto) and LVM you add even more layers with their own settings. For example, if the physical device has a read ahead of 128 blocks and the RAID has a readahead of 64 blocks, which is honored when I do a read from /dev/md0? Does the md driver attempt a 64 block read which the physical device driver then translates to a read of 128 blocks? Or does the RAID readahead "pass-through" to the underlying device, resulting in a 64 block read? The same kind of question holds for schedulers? Do I have to worry about multiple layers of IO schedulers and how they interact, or does the /dev/md0 effectively override underlying schedulers? In my attempts to answer this question, I've dug up some interesting data on schedulers and tools which might help figure this out: Linux Disk Scheduler Benchmarking from Google blktrace - generate traces of the i/o traffic on block devices Relevant Linux kernel mailing list thread

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  • Does Mac OS X throttle the RATE of socket creation?

    - by pbhogan
    This may seem programming related, but this is an OS question. I'm writing a small high performance daemon that takes thousands of connections per second. It's working fine on Linux (specifically Ubuntu 9.10 on EC2). On Mac OS X if I throw a few thousand connections at it (roughly about 16350) in a benchmark that simply opens a connection, does it's thing and closes the connection, then the benchmark program hangs for several seconds waiting for a socket to become available before continuing (or timing out in the process). I used both Apache Bench as well as Siege (to make sure it wasn't the benchmark application). So why/how is Mac OS X limiting the RATE at which sockets can be used, and can I stop it from doing this? Or is there something else going on? I know there is a file descriptor limit, but I'm not hitting that. There is no error on accepting a socket, it's simply hangs for a while after the first (roughly) 16000, waiting -- I assume -- for the OS to release a socket. This shouldn't happen since all prior the sockets are closed at that point. They're supposed to come available at the rate they're closed, and do on Ubuntu, but there seems to be some kind of multi (5-10?) second delay on Mac OS X. I tried tweaking with ulimit every-which-way. Nada.

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  • Does Mac OS X throttle the RATE of socket creation?

    - by pbhogan
    This may seem programming related, but this is an OS question. I'm writing a small high performance daemon that takes thousands of connections per second. It's working fine on Linux (specifically Ubuntu 9.10 on EC2). On Mac OS X if I throw a few thousand connections at it (roughly about 16350) in a benchmark that simply opens a connection, does it's thing and closes the connection, then the benchmark program hangs for several seconds waiting for a socket to become available before continuing (or timing out in the process). I used both Apache Bench as well as Siege (to make sure it wasn't the benchmark application). So why/how is Mac OS X limiting the RATE at which sockets can be used, and can I stop it from doing this? Or is there something else going on? I know there is a file descriptor limit, but I'm not hitting that. There is no error on accepting a socket, it's simply hangs for a while after the first (roughly) 16000, waiting -- I assume -- for the OS to release a socket. This shouldn't happen since all prior the sockets are closed at that point. They're supposed to come available at the rate they're closed, and do on Ubuntu, but there seems to be some kind of multi (5-10?) second delay on Mac OS X. I tried tweaking with ulimit every-which-way. Nada.

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  • External HDD connecting via USB disconnects wireless LAN connection

    - by Kensai
    Strange problem. I have this MEDION Akoya PC that has a dedicated bay to slide an external HDD sold separately. It's very handy indeed cause the slot is providing a fast USB 3 connection and power to the HDD unit, without extra cables. All works fine except this show-stopper behavior to disconnect me from the router once I slide in the unit and it powers up. The moment I connect the unit the (normally) three-four WiFi connections I see in my neighborhood disappear and my own to the router loses its signal strength (no Internet traffic is possible). After a while it throws me off that one as well, never to connect me again as long as the unit is powered. Once I disconnect the HDD the various signals come back and it automatically reconnects to my own. What takes? Are we in front of a serious design fault by MEDION here? Does the spinning of the HDD on top of the PC cause electromagnetic interference strong enough to throw off my WiFi connectivity? Is it a simple USB problem? Some kind of strange hardware conflict? Where should I look?

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  • Multi-petabyte scale out storage solution [closed]

    - by Alex Yuriev
    Let's say that I have a need to have a single-name space scale to multi-petabyte object store with a file system-like wrapper. What is currently out there that supports the following: Single name space that can take 1B files. Support for multiple entry points using NFS At least node level replication ( preferably node and file level replication ) Online software upgrades No "magic sauce" on the storage layer The following has been evaluated: Gluster & Lustre - just ick - fundamental lack of understanding of why online upgrades are mandatory. OneFS - we have it. It is smelling more and more like it hides a dead body under the hood. Other than MapR and zfs am I missing anything? P.S. Oh yes, I keep forgetting that the forums are for people to discuss if 2TB drive actually stores 2TB info. May bad. Seriously though - how the heck can "meets the following requirements" can be considered a "debate"? P.P.S. I did not throw an idiotic insult - i pointed out that this is actually an interesting question compared to a conversation about storage capacity of a 2TB hard drive. It is not a question of what works better - it is a question that asks did I miss any of the products that currently exist which fit the criteria where criteria is clearly outline. I got one answer below which included something that I have not looked at in a long time which looks quite a bit grown up compared to the time I briefly look at it before.

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  • Is a modem required to be programmed when using with an internet provider?

    - by Tim
    I wonder if a modem is required to be programmed when using with an internet provider? If yes, what is the purpose of programming a modem? Do both a DSL and a cable ISP both require a modem to be used in an individual home? For example, I have a Motorola modem SURFboard Model:SB5101, Customer S/N: xxx S/N? xxx HFC MAC ID: xxx USB CPE MAC ID: xxx a coil of cable and a splitter from Comcast High-Speed internet Self-Installation Kit, which were bought 5 years ago, when I purchased Comcast internet service from its retailer www.comcastoffers.com. With them, I was hoping to reduce the amount of fee by avoiding to ask Comcast people to come over to install. But I remember at that time Comcast sent its technician here, dismissed my idea of self-installation, saying they needed to use their own modem and charging me a hefty fee, and so my equipments have never been used. I haven't been using Comcast for a long time. I wonder if my modem, cable and splitter (brand new, never used) are still good to use with an internet provider such as Comcast? If needed, we can ignore their policy and just consider the technology side? Or they are not good to use and I must throw them away like trash? Thanks and regards!

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  • Custom ASP.NET Routing to an HttpHandler

    - by Rick Strahl
    As of version 4.0 ASP.NET natively supports routing via the now built-in System.Web.Routing namespace. Routing features are automatically integrated into the HtttpRuntime via a few custom interfaces. New Web Forms Routing Support In ASP.NET 4.0 there are a host of improvements including routing support baked into Web Forms via a RouteData property available on the Page class and RouteCollection.MapPageRoute() route handler that makes it easy to route to Web forms. To map ASP.NET Page routes is as simple as setting up the routes with MapPageRoute:protected void Application_Start(object sender, EventArgs e) { RegisterRoutes(RouteTable.Routes); } void RegisterRoutes(RouteCollection routes) { routes.MapPageRoute("StockQuote", "StockQuote/{symbol}", "StockQuote.aspx"); routes.MapPageRoute("StockQuotes", "StockQuotes/{symbolList}", "StockQuotes.aspx"); } and then accessing the route data in the page you can then use the new Page class RouteData property to retrieve the dynamic route data information:public partial class StockQuote1 : System.Web.UI.Page { protected StockQuote Quote = null; protected void Page_Load(object sender, EventArgs e) { string symbol = RouteData.Values["symbol"] as string; StockServer server = new StockServer(); Quote = server.GetStockQuote(symbol); // display stock data in Page View } } Simple, quick and doesn’t require much explanation. If you’re using WebForms most of your routing needs should be served just fine by this simple mechanism. Kudos to the ASP.NET team for putting this in the box and making it easy! How Routing Works To handle Routing in ASP.NET involves these steps: Registering Routes Creating a custom RouteHandler to retrieve an HttpHandler Attaching RouteData to your HttpHandler Picking up Route Information in your Request code Registering routes makes ASP.NET aware of the Routes you want to handle via the static RouteTable.Routes collection. You basically add routes to this collection to let ASP.NET know which URL patterns it should watch for. You typically hook up routes off a RegisterRoutes method that fires in Application_Start as I did in the example above to ensure routes are added only once when the application first starts up. When you create a route, you pass in a RouteHandler instance which ASP.NET caches and reuses as routes are matched. Once registered ASP.NET monitors the routes and if a match is found just prior to the HttpHandler instantiation, ASP.NET uses the RouteHandler registered for the route and calls GetHandler() on it to retrieve an HttpHandler instance. The RouteHandler.GetHandler() method is responsible for creating an instance of an HttpHandler that is to handle the request and – if necessary – to assign any additional custom data to the handler. At minimum you probably want to pass the RouteData to the handler so the handler can identify the request based on the route data available. To do this you typically add  a RouteData property to your handler and then assign the property from the RouteHandlers request context. This is essentially how Page.RouteData comes into being and this approach should work well for any custom handler implementation that requires RouteData. It’s a shame that ASP.NET doesn’t have a top level intrinsic object that’s accessible off the HttpContext object to provide route data more generically, but since RouteData is directly tied to HttpHandlers and not all handlers support it it might cause some confusion of when it’s actually available. Bottom line is that if you want to hold on to RouteData you have to assign it to a custom property of the handler or else pass it to the handler via Context.Items[] object that can be retrieved on an as needed basis. It’s important to understand that routing is hooked up via RouteHandlers that are responsible for loading HttpHandler instances. RouteHandlers are invoked for every request that matches a route and through this RouteHandler instance the Handler gains access to the current RouteData. Because of this logic it’s important to understand that Routing is really tied to HttpHandlers and not available prior to handler instantiation, which is pretty late in the HttpRuntime’s request pipeline. IOW, Routing works with Handlers but not with earlier in the pipeline within Modules. Specifically ASP.NET calls RouteHandler.GetHandler() from the PostResolveRequestCache HttpRuntime pipeline event. Here’s the call stack at the beginning of the GetHandler() call: which fires just before handler resolution. Non-Page Routing – You need to build custom RouteHandlers If you need to route to a custom Http Handler or other non-Page (and non-MVC) endpoint in the HttpRuntime, there is no generic mapping support available. You need to create a custom RouteHandler that can manage creating an instance of an HttpHandler that is fired in response to a routed request. Depending on what you are doing this process can be simple or fairly involved as your code is responsible based on the route data provided which handler to instantiate, and more importantly how to pass the route data on to the Handler. Luckily creating a RouteHandler is easy by implementing the IRouteHandler interface which has only a single GetHttpHandler(RequestContext context) method. In this method you can pick up the requestContext.RouteData, instantiate the HttpHandler of choice, and assign the RouteData to it. Then pass back the handler and you’re done.Here’s a simple example of GetHttpHandler() method that dynamically creates a handler based on a passed in Handler type./// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } Note that this code checks for a specific type of handler and if it matches assigns the RouteData to this handler. This is optional but quite a common scenario if you want to work with RouteData. If the handler you need to instantiate isn’t under your control but you still need to pass RouteData to Handler code, an alternative is to pass the RouteData via the HttpContext.Items collection:IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; requestContext.HttpContext.Items["RouteData"] = requestContext.RouteData; return handler; } The code in the handler implementation can then pick up the RouteData from the context collection as needed:RouteData routeData = HttpContext.Current.Items["RouteData"] as RouteData This isn’t as clean as having an explicit RouteData property, but it does have the advantage that the route data is visible anywhere in the Handler’s code chain. It’s definitely preferable to create a custom property on your handler, but the Context work-around works in a pinch when you don’t’ own the handler code and have dynamic code executing as part of the handler execution. An Example of a Custom RouteHandler: Attribute Based Route Implementation In this post I’m going to discuss a custom routine implementation I built for my CallbackHandler class in the West Wind Web & Ajax Toolkit. CallbackHandler can be very easily used for creating AJAX, REST and POX requests following RPC style method mapping. You can pass parameters via URL query string, POST data or raw data structures, and you can retrieve results as JSON, XML or raw string/binary data. It’s a quick and easy way to build service interfaces with no fuss. As a quick review here’s how CallbackHandler works: You create an Http Handler that derives from CallbackHandler You implement methods that have a [CallbackMethod] Attribute and that’s it. Here’s an example of an CallbackHandler implementation in an ashx.cs based handler:// RestService.ashx.cs public class RestService : CallbackHandler { [CallbackMethod] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } } CallbackHandler makes it super easy to create a method on the server, pass data to it via POST, QueryString or raw JSON/XML data, and then retrieve the results easily back in various formats. This works wonderful and I’ve used these tools in many projects for myself and with clients. But one thing missing has been the ability to create clean URLs. Typical URLs looked like this: http://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuote&symbol=msfthttp://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuotes&symbolList=msft,intc,gld,slw,mwe&format=xml which works and is clear enough, but also clearly very ugly. It would be much nicer if URLs could look like this: http://www.west-wind.com//WestwindWebtoolkit/Samples/StockQuote/msfthttp://www.west-wind.com/WestwindWebtoolkit/Samples/StockQuotes/msft,intc,gld,slw?format=xml (the Virtual Root in this sample is WestWindWebToolkit/Samples and StockQuote/{symbol} is the route)(If you use FireFox try using the JSONView plug-in make it easier to view JSON content) So, taking a clue from the WCF REST tools that use RouteUrls I set out to create a way to specify RouteUrls for each of the endpoints. The change made basically allows changing the above to: [CallbackMethod(RouteUrl="RestService/StockQuote/{symbol}")] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod(RouteUrl = "RestService/StockQuotes/{symbolList}")] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } where a RouteUrl is specified as part of the Callback attribute. And with the changes made with RouteUrls I can now get URLs like the second set shown earlier. So how does that work? Let’s find out… How to Create Custom Routes As mentioned earlier Routing is made up of several steps: Creating a custom RouteHandler to create HttpHandler instances Mapping the actual Routes to the RouteHandler Retrieving the RouteData and actually doing something useful with it in the HttpHandler In the CallbackHandler routing example above this works out to something like this: Create a custom RouteHandler that includes a property to track the method to call Set up the routes using Reflection against the class Looking for any RouteUrls in the CallbackMethod attribute Add a RouteData property to the CallbackHandler so we can access the RouteData in the code of the handler Creating a Custom Route Handler To make the above work I created a custom RouteHandler class that includes the actual IRouteHandler implementation as well as a generic and static method to automatically register all routes marked with the [CallbackMethod(RouteUrl="…")] attribute. Here’s the code:/// <summary> /// Route handler that can create instances of CallbackHandler derived /// callback classes. The route handler tracks the method name and /// creates an instance of the service in a predictable manner /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler type</typeparam> public class CallbackHandlerRouteHandler : IRouteHandler { /// <summary> /// Method name that is to be called on this route. /// Set by the automatically generated RegisterRoutes /// invokation. /// </summary> public string MethodName { get; set; } /// <summary> /// The type of the handler we're going to instantiate. /// Needed so we can semi-generically instantiate the /// handler and call the method on it. /// </summary> public Type CallbackHandlerType { get; set; } /// <summary> /// Constructor to pass in the two required components we /// need to create an instance of our handler. /// </summary> /// <param name="methodName"></param> /// <param name="callbackHandlerType"></param> public CallbackHandlerRouteHandler(string methodName, Type callbackHandlerType) { MethodName = methodName; CallbackHandlerType = callbackHandlerType; } /// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } /// <summary> /// Generic method to register all routes from a CallbackHandler /// that have RouteUrls defined on the [CallbackMethod] attribute /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler Type</typeparam> /// <param name="routes"></param> public static void RegisterRoutes<TCallbackHandler>(RouteCollection routes) { // find all methods var methods = typeof(TCallbackHandler).GetMethods(BindingFlags.Instance | BindingFlags.Public); foreach (var method in methods) { var attrs = method.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (attrs.Length < 1) continue; CallbackMethodAttribute attr = attrs[0] as CallbackMethodAttribute; if (string.IsNullOrEmpty(attr.RouteUrl)) continue; // Add the route routes.Add(method.Name, new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler)))); } } } The RouteHandler implements IRouteHandler, and its responsibility via the GetHandler method is to create an HttpHandler based on the route data. When ASP.NET calls GetHandler it passes a requestContext parameter which includes a requestContext.RouteData property. This parameter holds the current request’s route data as well as an instance of the current RouteHandler. If you look at GetHttpHandler() you can see that the code creates an instance of the handler we are interested in and then sets the RouteData property on the handler. This is how you can pass the current request’s RouteData to the handler. The RouteData object also has a  RouteData.RouteHandler property that is also available to the Handler later, which is useful in order to get additional information about the current route. In our case here the RouteHandler includes a MethodName property that identifies the method to execute in the handler since that value no longer comes from the URL so we need to figure out the method name some other way. The method name is mapped explicitly when the RouteHandler is created and here the static method that auto-registers all CallbackMethods with RouteUrls sets the method name when it creates the routes while reflecting over the methods (more on this in a minute). The important point here is that you can attach additional properties to the RouteHandler and you can then later access the RouteHandler and its properties later in the Handler to pick up these custom values. This is a crucial feature in that the RouteHandler serves in passing additional context to the handler so it knows what actions to perform. The automatic route registration is handled by the static RegisterRoutes<TCallbackHandler> method. This method is generic and totally reusable for any CallbackHandler type handler. To register a CallbackHandler and any RouteUrls it has defined you simple use code like this in Application_Start (or other application startup code):protected void Application_Start(object sender, EventArgs e) { // Register Routes for RestService CallbackHandlerRouteHandler.RegisterRoutes<RestService>(RouteTable.Routes); } If you have multiple CallbackHandler style services you can make multiple calls to RegisterRoutes for each of the service types. RegisterRoutes internally uses reflection to run through all the methods of the Handler, looking for CallbackMethod attributes and whether a RouteUrl is specified. If it is a new instance of a CallbackHandlerRouteHandler is created and the name of the method and the type are set. routes.Add(method.Name,           new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler) )) ); While the routing with CallbackHandlerRouteHandler is set up automatically for all methods that use the RouteUrl attribute, you can also use code to hook up those routes manually and skip using the attribute. The code for this is straightforward and just requires that you manually map each individual route to each method you want a routed: protected void Application_Start(objectsender, EventArgs e){    RegisterRoutes(RouteTable.Routes);}void RegisterRoutes(RouteCollection routes) { routes.Add("StockQuote Route",new Route("StockQuote/{symbol}",                     new CallbackHandlerRouteHandler("GetStockQuote",typeof(RestService) ) ) );     routes.Add("StockQuotes Route",new Route("StockQuotes/{symbolList}",                     new CallbackHandlerRouteHandler("GetStockQuotes",typeof(RestService) ) ) );}I think it’s clearly easier to have CallbackHandlerRouteHandler.RegisterRoutes() do this automatically for you based on RouteUrl attributes, but some people have a real aversion to attaching logic via attributes. Just realize that the option to manually create your routes is available as well. Using the RouteData in the Handler A RouteHandler’s responsibility is to create an HttpHandler and as mentioned earlier, natively IHttpHandler doesn’t have any support for RouteData. In order to utilize RouteData in your handler code you have to pass the RouteData to the handler. In my CallbackHandlerRouteHandler when it creates the HttpHandler instance it creates the instance and then assigns the custom RouteData property on the handler:IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; Again this only works if you actually add a RouteData property to your handler explicitly as I did in my CallbackHandler implementation:/// <summary> /// Optionally store RouteData on this handler /// so we can access it internally /// </summary> public RouteData RouteData {get; set; } and the RouteHandler needs to set it when it creates the handler instance. Once you have the route data in your handler you can access Route Keys and Values and also the RouteHandler. Since my RouteHandler has a custom property for the MethodName to retrieve it from within the handler I can do something like this now to retrieve the MethodName (this example is actually not in the handler but target is an instance pass to the processor): // check for Route Data method name if (target is CallbackHandler) { var routeData = ((CallbackHandler)target).RouteData; if (routeData != null) methodToCall = ((CallbackHandlerRouteHandler)routeData.RouteHandler).MethodName; } When I need to access the dynamic values in the route ( symbol in StockQuote/{symbol}) I can retrieve it easily with the Values collection (RouteData.Values["symbol"]). In my CallbackHandler processing logic I’m basically looking for matching parameter names to Route parameters: // look for parameters in the routeif(routeData != null){    string parmString = routeData.Values[parameter.Name] as string;    adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType);} And with that we’ve come full circle. We’ve created a custom RouteHandler() that passes the RouteData to the handler it creates. We’ve registered our routes to use the RouteHandler, and we’ve utilized the route data in our handler. For completeness sake here’s the routine that executes a method call based on the parameters passed in and one of the options is to retrieve the inbound parameters off RouteData (as well as from POST data or QueryString parameters):internal object ExecuteMethod(string method, object target, string[] parameters, CallbackMethodParameterType paramType, ref CallbackMethodAttribute callbackMethodAttribute) { HttpRequest Request = HttpContext.Current.Request; object Result = null; // Stores parsed parameters (from string JSON or QUeryString Values) object[] adjustedParms = null; Type PageType = target.GetType(); MethodInfo MI = PageType.GetMethod(method, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); if (MI == null) throw new InvalidOperationException("Invalid Server Method."); object[] methods = MI.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (methods.Length < 1) throw new InvalidOperationException("Server method is not accessible due to missing CallbackMethod attribute"); if (callbackMethodAttribute != null) callbackMethodAttribute = methods[0] as CallbackMethodAttribute; ParameterInfo[] parms = MI.GetParameters(); JSONSerializer serializer = new JSONSerializer(); RouteData routeData = null; if (target is CallbackHandler) routeData = ((CallbackHandler)target).RouteData; int parmCounter = 0; adjustedParms = new object[parms.Length]; foreach (ParameterInfo parameter in parms) { // Retrieve parameters out of QueryString or POST buffer if (parameters == null) { // look for parameters in the route if (routeData != null) { string parmString = routeData.Values[parameter.Name] as string; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // GET parameter are parsed as plain string values - no JSON encoding else if (HttpContext.Current.Request.HttpMethod == "GET") { // Look up the parameter by name string parmString = Request.QueryString[parameter.Name]; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // POST parameters are treated as methodParameters that are JSON encoded else if (paramType == CallbackMethodParameterType.Json) //string newVariable = methodParameters.GetValue(parmCounter) as string; adjustedParms[parmCounter] = serializer.Deserialize(Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject( Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); } else if (paramType == CallbackMethodParameterType.Json) adjustedParms[parmCounter] = serializer.Deserialize(parameters[parmCounter], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject(parameters[parmCounter], parameter.ParameterType); parmCounter++; } Result = MI.Invoke(target, adjustedParms); return Result; } The code basically uses Reflection to loop through all the parameters available on the method and tries to assign the parameters from RouteData, QueryString or POST variables. The parameters are converted into their appropriate types and then used to eventually make a Reflection based method call. What’s sweet is that the RouteData retrieval is just another option for dealing with the inbound data in this scenario and it adds exactly two lines of code plus the code to retrieve the MethodName I showed previously – a seriously low impact addition that adds a lot of extra value to this endpoint callback processing implementation. Debugging your Routes If you create a lot of routes it’s easy to run into Route conflicts where multiple routes have the same path and overlap with each other. This can be difficult to debug especially if you are using automatically generated routes like the routes created by CallbackHandlerRouteHandler.RegisterRoutes. Luckily there’s a tool that can help you out with this nicely. Phill Haack created a RouteDebugging tool you can download and add to your project. The easiest way to do this is to grab and add this to your project is to use NuGet (Add Library Package from your Project’s Reference Nodes):   which adds a RouteDebug assembly to your project. Once installed you can easily debug your routes with this simple line of code which needs to be installed at application startup:protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); // Debug your routes RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes); } Any routed URL then displays something like this: The screen shows you your current route data and all the routes that are mapped along with a flag that displays which route was actually matched. This is useful – if you have any overlap of routes you will be able to see which routes are triggered – the first one in the sequence wins. This tool has saved my ass on a few occasions – and with NuGet now it’s easy to add it to your project in a few seconds and then remove it when you’re done. Routing Around Custom routing seems slightly complicated on first blush due to its disconnected components of RouteHandler, route registration and mapping of custom handlers. But once you understand the relationship between a RouteHandler, the RouteData and how to pass it to a handler, utilizing of Routing becomes a lot easier as you can easily pass context from the registration to the RouteHandler and through to the HttpHandler. The most important thing to understand when building custom routing solutions is to figure out how to map URLs in such a way that the handler can figure out all the pieces it needs to process the request. This can be via URL routing parameters and as I did in my example by passing additional context information as part of the RouteHandler instance that provides the proper execution context. In my case this ‘context’ was the method name, but it could be an actual static value like an enum identifying an operation or category in an application. Basically user supplied data comes in through the url and static application internal data can be passed via RouteHandler property values. Routing can make your application URLs easier to read by non-techie types regardless of whether you’re building Service type or REST applications, or full on Web interfaces. Routing in ASP.NET 4.0 makes it possible to create just about any extensionless URLs you can dream up and custom RouteHanmdler References Sample ProjectIncludes the sample CallbackHandler service discussed here along with compiled versionsof the Westwind.Web and Westwind.Utilities assemblies.  (requires .NET 4.0/VS 2010) West Wind Web Toolkit includes full implementation of CallbackHandler and the Routing Handler West Wind Web Toolkit Source CodeContains the full source code to the Westwind.Web and Westwind.Utilities assemblies usedin these samples. Includes the source described in the post.(Latest build in the Subversion Repository) CallbackHandler Source(Relevant code to this article tree in Westwind.Web assembly) JSONView FireFoxPluginA simple FireFox Plugin to easily view JSON data natively in FireFox.For IE you can use a registry hack to display JSON as raw text.© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  HTTP  

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  • Introduction to the ASP.NET Web API

    - by Stephen.Walther
    I am a huge fan of Ajax. If you want to create a great experience for the users of your website – regardless of whether you are building an ASP.NET MVC or an ASP.NET Web Forms site — then you need to use Ajax. Otherwise, you are just being cruel to your customers. We use Ajax extensively in several of the ASP.NET applications that my company, Superexpert.com, builds. We expose data from the server as JSON and use jQuery to retrieve and update that data from the browser. One challenge, when building an ASP.NET website, is deciding on which technology to use to expose JSON data from the server. For example, how do you expose a list of products from the server as JSON so you can retrieve the list of products with jQuery? You have a number of options (too many options) including ASMX Web services, WCF Web Services, ASHX Generic Handlers, WCF Data Services, and MVC controller actions. Fortunately, the world has just been simplified. With the release of ASP.NET 4 Beta, Microsoft has introduced a new technology for exposing JSON from the server named the ASP.NET Web API. You can use the ASP.NET Web API with both ASP.NET MVC and ASP.NET Web Forms applications. The goal of this blog post is to provide you with a brief overview of the features of the new ASP.NET Web API. You learn how to use the ASP.NET Web API to retrieve, insert, update, and delete database records with jQuery. We also discuss how you can perform form validation when using the Web API and use OData when using the Web API. Creating an ASP.NET Web API Controller The ASP.NET Web API exposes JSON data through a new type of controller called an API controller. You can add an API controller to an existing ASP.NET MVC 4 project through the standard Add Controller dialog box. Right-click your Controllers folder and select Add, Controller. In the dialog box, name your controller MovieController and select the Empty API controller template: A brand new API controller looks like this: using System; using System.Collections.Generic; using System.Linq; using System.Net.Http; using System.Web.Http; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { } } An API controller, unlike a standard MVC controller, derives from the base ApiController class instead of the base Controller class. Using jQuery to Retrieve, Insert, Update, and Delete Data Let’s create an Ajaxified Movie Database application. We’ll retrieve, insert, update, and delete movies using jQuery with the MovieController which we just created. Our Movie model class looks like this: namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } public string Title { get; set; } public string Director { get; set; } } } Our application will consist of a single HTML page named Movies.html. We’ll place all of our jQuery code in the Movies.html page. Getting a Single Record with the ASP.NET Web API To support retrieving a single movie from the server, we need to add a Get method to our API controller: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public Movie GetMovie(int id) { // Return movie by id if (id == 1) { return new Movie { Id = 1, Title = "Star Wars", Director = "Lucas" }; } // Otherwise, movie was not found throw new HttpResponseException(HttpStatusCode.NotFound); } } } In the code above, the GetMovie() method accepts the Id of a movie. If the Id has the value 1 then the method returns the movie Star Wars. Otherwise, the method throws an exception and returns 404 Not Found HTTP status code. After building your project, you can invoke the MovieController.GetMovie() method by entering the following URL in your web browser address bar: http://localhost:[port]/api/movie/1 (You’ll need to enter the correct randomly generated port). In the URL api/movie/1, the first “api” segment indicates that this is a Web API route. The “movie” segment indicates that the MovieController should be invoked. You do not specify the name of the action. Instead, the HTTP method used to make the request – GET, POST, PUT, DELETE — is used to identify the action to invoke. The ASP.NET Web API uses different routing conventions than normal ASP.NET MVC controllers. When you make an HTTP GET request then any API controller method with a name that starts with “GET” is invoked. So, we could have called our API controller action GetPopcorn() instead of GetMovie() and it would still be invoked by the URL api/movie/1. The default route for the Web API is defined in the Global.asax file and it looks like this: routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); We can invoke our GetMovie() controller action with the jQuery code in the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Get Movie</title> </head> <body> <div> Title: <span id="title"></span> </div> <div> Director: <span id="director"></span> </div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> getMovie(1, function (movie) { $("#title").html(movie.Title); $("#director").html(movie.Director); }); function getMovie(id, callback) { $.ajax({ url: "/api/Movie", data: { id: id }, type: "GET", contentType: "application/json;charset=utf-8", statusCode: { 200: function (movie) { callback(movie); }, 404: function () { alert("Not Found!"); } } }); } </script> </body> </html> In the code above, the jQuery $.ajax() method is used to invoke the GetMovie() method. Notice that the Ajax call handles two HTTP response codes. When the GetMove() method successfully returns a movie, the method returns a 200 status code. In that case, the details of the movie are displayed in the HTML page. Otherwise, if the movie is not found, the GetMovie() method returns a 404 status code. In that case, the page simply displays an alert box indicating that the movie was not found (hopefully, you would implement something more graceful in an actual application). You can use your browser’s Developer Tools to see what is going on in the background when you open the HTML page (hit F12 in the most recent version of most browsers). For example, you can use the Network tab in Google Chrome to see the Ajax request which invokes the GetMovie() method: Getting a Set of Records with the ASP.NET Web API Let’s modify our Movie API controller so that it returns a collection of movies. The following Movie controller has a new ListMovies() method which returns a (hard-coded) collection of movies: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public IEnumerable<Movie> ListMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=1, Title="King Kong", Director="Jackson"}, new Movie {Id=1, Title="Memento", Director="Nolan"} }; } } } Because we named our action ListMovies(), the default Web API route will never match it. Therefore, we need to add the following custom route to our Global.asax file (at the top of the RegisterRoutes() method): routes.MapHttpRoute( name: "ActionApi", routeTemplate: "api/{controller}/{action}/{id}", defaults: new { id = RouteParameter.Optional } ); This route enables us to invoke the ListMovies() method with the URL /api/movie/listmovies. Now that we have exposed our collection of movies from the server, we can retrieve and display the list of movies using jQuery in our HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>List Movies</title> </head> <body> <div id="movies"></div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> listMovies(function (movies) { var strMovies=""; $.each(movies, function (index, movie) { strMovies += "<div>" + movie.Title + "</div>"; }); $("#movies").html(strMovies); }); function listMovies(callback) { $.ajax({ url: "/api/Movie/ListMovies", data: {}, type: "GET", contentType: "application/json;charset=utf-8", }).then(function(movies){ callback(movies); }); } </script> </body> </html>     Inserting a Record with the ASP.NET Web API Now let’s modify our Movie API controller so it supports creating new records: public HttpResponseMessage<Movie> PostMovie(Movie movieToCreate) { // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } The PostMovie() method in the code above accepts a movieToCreate parameter. We don’t actually store the new movie anywhere. In real life, you will want to call a service method to store the new movie in a database. When you create a new resource, such as a new movie, you should return the location of the new resource. In the code above, the URL where the new movie can be retrieved is assigned to the Location header returned in the PostMovie() response. Because the name of our method starts with “Post”, we don’t need to create a custom route. The PostMovie() method can be invoked with the URL /Movie/PostMovie – just as long as the method is invoked within the context of a HTTP POST request. The following HTML page invokes the PostMovie() method. <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "Jackson" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }); function createMovie(movieToCreate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); } </script> </body> </html> This page creates a new movie (the Hobbit) by calling the createMovie() method. The page simply displays the Id of the new movie: The HTTP Post operation is performed with the following call to the jQuery $.ajax() method: $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); Notice that the type of Ajax request is a POST request. This is required to match the PostMovie() method. Notice, furthermore, that the new movie is converted into JSON using JSON.stringify(). The JSON.stringify() method takes a JavaScript object and converts it into a JSON string. Finally, notice that success is represented with a 201 status code. The HttpStatusCode.Created value returned from the PostMovie() method returns a 201 status code. Updating a Record with the ASP.NET Web API Here’s how we can modify the Movie API controller to support updating an existing record. In this case, we need to create a PUT method to handle an HTTP PUT request: public void PutMovie(Movie movieToUpdate) { if (movieToUpdate.Id == 1) { // Update the movie in the database return; } // If you can't find the movie to update throw new HttpResponseException(HttpStatusCode.NotFound); } Unlike our PostMovie() method, the PutMovie() method does not return a result. The action either updates the database or, if the movie cannot be found, returns an HTTP Status code of 404. The following HTML page illustrates how you can invoke the PutMovie() method: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Put Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToUpdate = { id: 1, title: "The Hobbit", director: "Jackson" }; updateMovie(movieToUpdate, function () { alert("Movie updated!"); }); function updateMovie(movieToUpdate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToUpdate), type: "PUT", contentType: "application/json;charset=utf-8", statusCode: { 200: function () { callback(); }, 404: function () { alert("Movie not found!"); } } }); } </script> </body> </html> Deleting a Record with the ASP.NET Web API Here’s the code for deleting a movie: public HttpResponseMessage DeleteMovie(int id) { // Delete the movie from the database // Return status code return new HttpResponseMessage(HttpStatusCode.NoContent); } This method simply deletes the movie (well, not really, but pretend that it does) and returns a No Content status code (204). The following page illustrates how you can invoke the DeleteMovie() action: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Delete Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> deleteMovie(1, function () { alert("Movie deleted!"); }); function deleteMovie(id, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify({id:id}), type: "DELETE", contentType: "application/json;charset=utf-8", statusCode: { 204: function () { callback(); } } }); } </script> </body> </html> Performing Validation How do you perform form validation when using the ASP.NET Web API? Because validation in ASP.NET MVC is driven by the Default Model Binder, and because the Web API uses the Default Model Binder, you get validation for free. Let’s modify our Movie class so it includes some of the standard validation attributes: using System.ComponentModel.DataAnnotations; namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } [Required(ErrorMessage="Title is required!")] [StringLength(5, ErrorMessage="Title cannot be more than 5 characters!")] public string Title { get; set; } [Required(ErrorMessage="Director is required!")] public string Director { get; set; } } } In the code above, the Required validation attribute is used to make both the Title and Director properties required. The StringLength attribute is used to require the length of the movie title to be no more than 5 characters. Now let’s modify our PostMovie() action to validate a movie before adding the movie to the database: public HttpResponseMessage PostMovie(Movie movieToCreate) { // Validate movie if (!ModelState.IsValid) { var errors = new JsonArray(); foreach (var prop in ModelState.Values) { if (prop.Errors.Any()) { errors.Add(prop.Errors.First().ErrorMessage); } } return new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } If ModelState.IsValid has the value false then the errors in model state are copied to a new JSON array. Each property – such as the Title and Director property — can have multiple errors. In the code above, only the first error message is copied over. The JSON array is returned with a Bad Request status code (400 status code). The following HTML page illustrates how you can invoke our modified PostMovie() action and display any error messages: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }, function (errors) { var strErrors = ""; $.each(errors, function(index, err) { strErrors += "*" + err + "\n"; }); alert(strErrors); } ); function createMovie(movieToCreate, success, fail) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToCreate), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { success(newMovie); }, 400: function (xhr) { var errors = JSON.parse(xhr.responseText); fail(errors); } } }); } </script> </body> </html> The createMovie() function performs an Ajax request and handles either a 201 or a 400 status code from the response. If a 201 status code is returned then there were no validation errors and the new movie was created. If, on the other hand, a 400 status code is returned then there was a validation error. The validation errors are retrieved from the XmlHttpRequest responseText property. The error messages are displayed in an alert: (Please don’t use JavaScript alert dialogs to display validation errors, I just did it this way out of pure laziness) This validation code in our PostMovie() method is pretty generic. There is nothing specific about this code to the PostMovie() method. In the following video, Jon Galloway demonstrates how to create a global Validation filter which can be used with any API controller action: http://www.asp.net/web-api/overview/web-api-routing-and-actions/video-custom-validation His validation filter looks like this: using System.Json; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http.Controllers; using System.Web.Http.Filters; namespace MyWebAPIApp.Filters { public class ValidationActionFilter:ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { var modelState = actionContext.ModelState; if (!modelState.IsValid) { dynamic errors = new JsonObject(); foreach (var key in modelState.Keys) { var state = modelState[key]; if (state.Errors.Any()) { errors[key] = state.Errors.First().ErrorMessage; } } actionContext.Response = new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } } } } And you can register the validation filter in the Application_Start() method in the Global.asax file like this: GlobalConfiguration.Configuration.Filters.Add(new ValidationActionFilter()); After you register the Validation filter, validation error messages are returned from any API controller action method automatically when validation fails. You don’t need to add any special logic to any of your API controller actions to take advantage of the filter. Querying using OData The OData protocol is an open protocol created by Microsoft which enables you to perform queries over the web. The official website for OData is located here: http://odata.org For example, here are some of the query options which you can use with OData: · $orderby – Enables you to retrieve results in a certain order. · $top – Enables you to retrieve a certain number of results. · $skip – Enables you to skip over a certain number of results (use with $top for paging). · $filter – Enables you to filter the results returned. The ASP.NET Web API supports a subset of the OData protocol. You can use all of the query options listed above when interacting with an API controller. The only requirement is that the API controller action returns its data as IQueryable. For example, the following Movie controller has an action named GetMovies() which returns an IQueryable of movies: public IQueryable<Movie> GetMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=2, Title="King Kong", Director="Jackson"}, new Movie {Id=3, Title="Willow", Director="Lucas"}, new Movie {Id=4, Title="Shrek", Director="Smith"}, new Movie {Id=5, Title="Memento", Director="Nolan"} }.AsQueryable(); } If you enter the following URL in your browser: /api/movie?$top=2&$orderby=Title Then you will limit the movies returned to the top 2 in order of the movie Title. You will get the following results: By using the $top option in combination with the $skip option, you can enable client-side paging. For example, you can use $top and $skip to page through thousands of products, 10 products at a time. The $filter query option is very powerful. You can use this option to filter the results from a query. Here are some examples: Return every movie directed by Lucas: /api/movie?$filter=Director eq ‘Lucas’ Return every movie which has a title which starts with ‘S’: /api/movie?$filter=startswith(Title,’S') Return every movie which has an Id greater than 2: /api/movie?$filter=Id gt 2 The complete documentation for the $filter option is located here: http://www.odata.org/developers/protocols/uri-conventions#FilterSystemQueryOption Summary The goal of this blog entry was to provide you with an overview of the new ASP.NET Web API introduced with the Beta release of ASP.NET 4. In this post, I discussed how you can retrieve, insert, update, and delete data by using jQuery with the Web API. I also discussed how you can use the standard validation attributes with the Web API. You learned how to return validation error messages to the client and display the error messages using jQuery. Finally, we briefly discussed how the ASP.NET Web API supports the OData protocol. For example, you learned how to filter records returned from an API controller action by using the $filter query option. I’m excited about the new Web API. This is a feature which I expect to use with almost every ASP.NET application which I build in the future.

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  • Introduction to the ASP.NET Web API

    - by Stephen.Walther
    I am a huge fan of Ajax. If you want to create a great experience for the users of your website – regardless of whether you are building an ASP.NET MVC or an ASP.NET Web Forms site — then you need to use Ajax. Otherwise, you are just being cruel to your customers. We use Ajax extensively in several of the ASP.NET applications that my company, Superexpert.com, builds. We expose data from the server as JSON and use jQuery to retrieve and update that data from the browser. One challenge, when building an ASP.NET website, is deciding on which technology to use to expose JSON data from the server. For example, how do you expose a list of products from the server as JSON so you can retrieve the list of products with jQuery? You have a number of options (too many options) including ASMX Web services, WCF Web Services, ASHX Generic Handlers, WCF Data Services, and MVC controller actions. Fortunately, the world has just been simplified. With the release of ASP.NET 4 Beta, Microsoft has introduced a new technology for exposing JSON from the server named the ASP.NET Web API. You can use the ASP.NET Web API with both ASP.NET MVC and ASP.NET Web Forms applications. The goal of this blog post is to provide you with a brief overview of the features of the new ASP.NET Web API. You learn how to use the ASP.NET Web API to retrieve, insert, update, and delete database records with jQuery. We also discuss how you can perform form validation when using the Web API and use OData when using the Web API. Creating an ASP.NET Web API Controller The ASP.NET Web API exposes JSON data through a new type of controller called an API controller. You can add an API controller to an existing ASP.NET MVC 4 project through the standard Add Controller dialog box. Right-click your Controllers folder and select Add, Controller. In the dialog box, name your controller MovieController and select the Empty API controller template: A brand new API controller looks like this: using System; using System.Collections.Generic; using System.Linq; using System.Net.Http; using System.Web.Http; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { } } An API controller, unlike a standard MVC controller, derives from the base ApiController class instead of the base Controller class. Using jQuery to Retrieve, Insert, Update, and Delete Data Let’s create an Ajaxified Movie Database application. We’ll retrieve, insert, update, and delete movies using jQuery with the MovieController which we just created. Our Movie model class looks like this: namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } public string Title { get; set; } public string Director { get; set; } } } Our application will consist of a single HTML page named Movies.html. We’ll place all of our jQuery code in the Movies.html page. Getting a Single Record with the ASP.NET Web API To support retrieving a single movie from the server, we need to add a Get method to our API controller: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public Movie GetMovie(int id) { // Return movie by id if (id == 1) { return new Movie { Id = 1, Title = "Star Wars", Director = "Lucas" }; } // Otherwise, movie was not found throw new HttpResponseException(HttpStatusCode.NotFound); } } } In the code above, the GetMovie() method accepts the Id of a movie. If the Id has the value 1 then the method returns the movie Star Wars. Otherwise, the method throws an exception and returns 404 Not Found HTTP status code. After building your project, you can invoke the MovieController.GetMovie() method by entering the following URL in your web browser address bar: http://localhost:[port]/api/movie/1 (You’ll need to enter the correct randomly generated port). In the URL api/movie/1, the first “api” segment indicates that this is a Web API route. The “movie” segment indicates that the MovieController should be invoked. You do not specify the name of the action. Instead, the HTTP method used to make the request – GET, POST, PUT, DELETE — is used to identify the action to invoke. The ASP.NET Web API uses different routing conventions than normal ASP.NET MVC controllers. When you make an HTTP GET request then any API controller method with a name that starts with “GET” is invoked. So, we could have called our API controller action GetPopcorn() instead of GetMovie() and it would still be invoked by the URL api/movie/1. The default route for the Web API is defined in the Global.asax file and it looks like this: routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); We can invoke our GetMovie() controller action with the jQuery code in the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Get Movie</title> </head> <body> <div> Title: <span id="title"></span> </div> <div> Director: <span id="director"></span> </div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> getMovie(1, function (movie) { $("#title").html(movie.Title); $("#director").html(movie.Director); }); function getMovie(id, callback) { $.ajax({ url: "/api/Movie", data: { id: id }, type: "GET", contentType: "application/json;charset=utf-8", statusCode: { 200: function (movie) { callback(movie); }, 404: function () { alert("Not Found!"); } } }); } </script> </body> </html> In the code above, the jQuery $.ajax() method is used to invoke the GetMovie() method. Notice that the Ajax call handles two HTTP response codes. When the GetMove() method successfully returns a movie, the method returns a 200 status code. In that case, the details of the movie are displayed in the HTML page. Otherwise, if the movie is not found, the GetMovie() method returns a 404 status code. In that case, the page simply displays an alert box indicating that the movie was not found (hopefully, you would implement something more graceful in an actual application). You can use your browser’s Developer Tools to see what is going on in the background when you open the HTML page (hit F12 in the most recent version of most browsers). For example, you can use the Network tab in Google Chrome to see the Ajax request which invokes the GetMovie() method: Getting a Set of Records with the ASP.NET Web API Let’s modify our Movie API controller so that it returns a collection of movies. The following Movie controller has a new ListMovies() method which returns a (hard-coded) collection of movies: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public IEnumerable<Movie> ListMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=1, Title="King Kong", Director="Jackson"}, new Movie {Id=1, Title="Memento", Director="Nolan"} }; } } } Because we named our action ListMovies(), the default Web API route will never match it. Therefore, we need to add the following custom route to our Global.asax file (at the top of the RegisterRoutes() method): routes.MapHttpRoute( name: "ActionApi", routeTemplate: "api/{controller}/{action}/{id}", defaults: new { id = RouteParameter.Optional } ); This route enables us to invoke the ListMovies() method with the URL /api/movie/listmovies. Now that we have exposed our collection of movies from the server, we can retrieve and display the list of movies using jQuery in our HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>List Movies</title> </head> <body> <div id="movies"></div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> listMovies(function (movies) { var strMovies=""; $.each(movies, function (index, movie) { strMovies += "<div>" + movie.Title + "</div>"; }); $("#movies").html(strMovies); }); function listMovies(callback) { $.ajax({ url: "/api/Movie/ListMovies", data: {}, type: "GET", contentType: "application/json;charset=utf-8", }).then(function(movies){ callback(movies); }); } </script> </body> </html>     Inserting a Record with the ASP.NET Web API Now let’s modify our Movie API controller so it supports creating new records: public HttpResponseMessage<Movie> PostMovie(Movie movieToCreate) { // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } The PostMovie() method in the code above accepts a movieToCreate parameter. We don’t actually store the new movie anywhere. In real life, you will want to call a service method to store the new movie in a database. When you create a new resource, such as a new movie, you should return the location of the new resource. In the code above, the URL where the new movie can be retrieved is assigned to the Location header returned in the PostMovie() response. Because the name of our method starts with “Post”, we don’t need to create a custom route. The PostMovie() method can be invoked with the URL /Movie/PostMovie – just as long as the method is invoked within the context of a HTTP POST request. The following HTML page invokes the PostMovie() method. <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "Jackson" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }); function createMovie(movieToCreate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); } </script> </body> </html> This page creates a new movie (the Hobbit) by calling the createMovie() method. The page simply displays the Id of the new movie: The HTTP Post operation is performed with the following call to the jQuery $.ajax() method: $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); Notice that the type of Ajax request is a POST request. This is required to match the PostMovie() method. Notice, furthermore, that the new movie is converted into JSON using JSON.stringify(). The JSON.stringify() method takes a JavaScript object and converts it into a JSON string. Finally, notice that success is represented with a 201 status code. The HttpStatusCode.Created value returned from the PostMovie() method returns a 201 status code. Updating a Record with the ASP.NET Web API Here’s how we can modify the Movie API controller to support updating an existing record. In this case, we need to create a PUT method to handle an HTTP PUT request: public void PutMovie(Movie movieToUpdate) { if (movieToUpdate.Id == 1) { // Update the movie in the database return; } // If you can't find the movie to update throw new HttpResponseException(HttpStatusCode.NotFound); } Unlike our PostMovie() method, the PutMovie() method does not return a result. The action either updates the database or, if the movie cannot be found, returns an HTTP Status code of 404. The following HTML page illustrates how you can invoke the PutMovie() method: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Put Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToUpdate = { id: 1, title: "The Hobbit", director: "Jackson" }; updateMovie(movieToUpdate, function () { alert("Movie updated!"); }); function updateMovie(movieToUpdate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToUpdate), type: "PUT", contentType: "application/json;charset=utf-8", statusCode: { 200: function () { callback(); }, 404: function () { alert("Movie not found!"); } } }); } </script> </body> </html> Deleting a Record with the ASP.NET Web API Here’s the code for deleting a movie: public HttpResponseMessage DeleteMovie(int id) { // Delete the movie from the database // Return status code return new HttpResponseMessage(HttpStatusCode.NoContent); } This method simply deletes the movie (well, not really, but pretend that it does) and returns a No Content status code (204). The following page illustrates how you can invoke the DeleteMovie() action: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Delete Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> deleteMovie(1, function () { alert("Movie deleted!"); }); function deleteMovie(id, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify({id:id}), type: "DELETE", contentType: "application/json;charset=utf-8", statusCode: { 204: function () { callback(); } } }); } </script> </body> </html> Performing Validation How do you perform form validation when using the ASP.NET Web API? Because validation in ASP.NET MVC is driven by the Default Model Binder, and because the Web API uses the Default Model Binder, you get validation for free. Let’s modify our Movie class so it includes some of the standard validation attributes: using System.ComponentModel.DataAnnotations; namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } [Required(ErrorMessage="Title is required!")] [StringLength(5, ErrorMessage="Title cannot be more than 5 characters!")] public string Title { get; set; } [Required(ErrorMessage="Director is required!")] public string Director { get; set; } } } In the code above, the Required validation attribute is used to make both the Title and Director properties required. The StringLength attribute is used to require the length of the movie title to be no more than 5 characters. Now let’s modify our PostMovie() action to validate a movie before adding the movie to the database: public HttpResponseMessage PostMovie(Movie movieToCreate) { // Validate movie if (!ModelState.IsValid) { var errors = new JsonArray(); foreach (var prop in ModelState.Values) { if (prop.Errors.Any()) { errors.Add(prop.Errors.First().ErrorMessage); } } return new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } If ModelState.IsValid has the value false then the errors in model state are copied to a new JSON array. Each property – such as the Title and Director property — can have multiple errors. In the code above, only the first error message is copied over. The JSON array is returned with a Bad Request status code (400 status code). The following HTML page illustrates how you can invoke our modified PostMovie() action and display any error messages: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }, function (errors) { var strErrors = ""; $.each(errors, function(index, err) { strErrors += "*" + err + "n"; }); alert(strErrors); } ); function createMovie(movieToCreate, success, fail) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToCreate), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { success(newMovie); }, 400: function (xhr) { var errors = JSON.parse(xhr.responseText); fail(errors); } } }); } </script> </body> </html> The createMovie() function performs an Ajax request and handles either a 201 or a 400 status code from the response. If a 201 status code is returned then there were no validation errors and the new movie was created. If, on the other hand, a 400 status code is returned then there was a validation error. The validation errors are retrieved from the XmlHttpRequest responseText property. The error messages are displayed in an alert: (Please don’t use JavaScript alert dialogs to display validation errors, I just did it this way out of pure laziness) This validation code in our PostMovie() method is pretty generic. There is nothing specific about this code to the PostMovie() method. In the following video, Jon Galloway demonstrates how to create a global Validation filter which can be used with any API controller action: http://www.asp.net/web-api/overview/web-api-routing-and-actions/video-custom-validation His validation filter looks like this: using System.Json; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http.Controllers; using System.Web.Http.Filters; namespace MyWebAPIApp.Filters { public class ValidationActionFilter:ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { var modelState = actionContext.ModelState; if (!modelState.IsValid) { dynamic errors = new JsonObject(); foreach (var key in modelState.Keys) { var state = modelState[key]; if (state.Errors.Any()) { errors[key] = state.Errors.First().ErrorMessage; } } actionContext.Response = new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } } } } And you can register the validation filter in the Application_Start() method in the Global.asax file like this: GlobalConfiguration.Configuration.Filters.Add(new ValidationActionFilter()); After you register the Validation filter, validation error messages are returned from any API controller action method automatically when validation fails. You don’t need to add any special logic to any of your API controller actions to take advantage of the filter. Querying using OData The OData protocol is an open protocol created by Microsoft which enables you to perform queries over the web. The official website for OData is located here: http://odata.org For example, here are some of the query options which you can use with OData: · $orderby – Enables you to retrieve results in a certain order. · $top – Enables you to retrieve a certain number of results. · $skip – Enables you to skip over a certain number of results (use with $top for paging). · $filter – Enables you to filter the results returned. The ASP.NET Web API supports a subset of the OData protocol. You can use all of the query options listed above when interacting with an API controller. The only requirement is that the API controller action returns its data as IQueryable. For example, the following Movie controller has an action named GetMovies() which returns an IQueryable of movies: public IQueryable<Movie> GetMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=2, Title="King Kong", Director="Jackson"}, new Movie {Id=3, Title="Willow", Director="Lucas"}, new Movie {Id=4, Title="Shrek", Director="Smith"}, new Movie {Id=5, Title="Memento", Director="Nolan"} }.AsQueryable(); } If you enter the following URL in your browser: /api/movie?$top=2&$orderby=Title Then you will limit the movies returned to the top 2 in order of the movie Title. You will get the following results: By using the $top option in combination with the $skip option, you can enable client-side paging. For example, you can use $top and $skip to page through thousands of products, 10 products at a time. The $filter query option is very powerful. You can use this option to filter the results from a query. Here are some examples: Return every movie directed by Lucas: /api/movie?$filter=Director eq ‘Lucas’ Return every movie which has a title which starts with ‘S’: /api/movie?$filter=startswith(Title,’S') Return every movie which has an Id greater than 2: /api/movie?$filter=Id gt 2 The complete documentation for the $filter option is located here: http://www.odata.org/developers/protocols/uri-conventions#FilterSystemQueryOption Summary The goal of this blog entry was to provide you with an overview of the new ASP.NET Web API introduced with the Beta release of ASP.NET 4. In this post, I discussed how you can retrieve, insert, update, and delete data by using jQuery with the Web API. I also discussed how you can use the standard validation attributes with the Web API. You learned how to return validation error messages to the client and display the error messages using jQuery. Finally, we briefly discussed how the ASP.NET Web API supports the OData protocol. For example, you learned how to filter records returned from an API controller action by using the $filter query option. I’m excited about the new Web API. This is a feature which I expect to use with almost every ASP.NET application which I build in the future.

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  • Java Cloud Service Integration to REST Service

    - by Jani Rautiainen
    Service (JCS) provides a platform to develop and deploy business applications in the cloud. In Fusion Applications Cloud deployments customers do not have the option to deploy custom applications developed with JDeveloper to ensure the integrity and supportability of the hosted application service. Instead the custom applications can be deployed to the JCS and integrated to the Fusion Application Cloud instance. This series of articles will go through the features of JCS, provide end-to-end examples on how to develop and deploy applications on JCS and how to integrate them with the Fusion Applications instance. In this article a custom application integrating with REST service will be implemented. We will use REST services provided by Taleo as an example; however the same approach will work with any REST service. In this example the data from the REST service is used to populate a dynamic table. Pre-requisites Access to Cloud instance In order to deploy the application access to a JCS instance is needed, a free trial JCS instance can be obtained from Oracle Cloud site. To register you will need a credit card even if the credit card will not be charged. To register simply click "Try it" and choose the "Java" option. The confirmation email will contain the connection details. See this video for example of the registration.Once the request is processed you will be assigned 2 service instances; Java and Database. Applications deployed to the JCS must use Oracle Database Cloud Service as their underlying database. So when JCS instance is created a database instance is associated with it using a JDBC data source.The cloud services can be monitored and managed through the web UI. For details refer to Getting Started with Oracle Cloud. JDeveloper JDeveloper contains Cloud specific features related to e.g. connection and deployment. To use these features download the JDeveloper from JDeveloper download site by clicking the "Download JDeveloper 11.1.1.7.1 for ADF deployment on Oracle Cloud" link, this version of JDeveloper will have the JCS integration features that will be used in this article. For versions that do not include the Cloud integration features the Oracle Java Cloud Service SDK or the JCS Java Console can be used for deployment. For details on installing and configuring the JDeveloper refer to the installation guideFor details on SDK refer to Using the Command-Line Interface to Monitor Oracle Java Cloud Service and Using the Command-Line Interface to Manage Oracle Java Cloud Service. Access to a local database The database associated with the JCS instance cannot be connected to with JDBC.  Since creating ADFbc business component requires a JDBC connection we will need access to a local database. 3rd party libraries This example will use some 3rd party libraries for implementing the REST service call and processing the input / output content. Other libraries may also be used, however these are tested to work. Jersey 1.x Jersey library will be used as a client to make the call to the REST service. JCS documentation for supported specifications states: Java API for RESTful Web Services (JAX-RS) 1.1 So Jersey 1.x will be used. Download the single-JAR Jersey bundle; in this example Jersey 1.18 JAR bundle is used. Json-simple Jjson-simple library will be used to process the json objects. Download the  JAR file; in this example json-simple-1.1.1.jar is used. Accessing data in Taleo Before implementing the application it is beneficial to familiarize oneself with the data in Taleo. Easiest way to do this is by using a RESTClient on your browser. Once added to the browser you can access the UI: The client can be used to call the REST services to test the URLs and data before adding them into the application. First derive the base URL for the service this can be done with: Method: GET URL: https://tbe.taleo.net/MANAGER/dispatcher/api/v1/serviceUrl/<company name> The response will contain the base URL to be used for the service calls for the company. Next obtain authentication token with: Method: POST URL: https://ch.tbe.taleo.net/CH07/ats/api/v1/login?orgCode=<company>&userName=<user name>&password=<password> The response includes an authentication token that can be used for few hours to authenticate with the service: {   "response": {     "authToken": "webapi26419680747505890557"   },   "status": {     "detail": {},     "success": true   } } To authenticate the service calls navigate to "Headers -> Custom Header": And add a new request header with: Name: Cookie Value: authToken=webapi26419680747505890557 Once authentication token is defined the tool can be used to invoke REST services; for example: Method: GET URL: https://ch.tbe.taleo.net/CH07/ats/api/v1/object/candidate/search.xml?status=16 This data will be used on the application to be created. For details on the Taleo REST services refer to the Taleo Business Edition REST API Guide. Create Application First Fusion Web Application is created and configured. Start JDeveloper and click "New Application": Application Name: JcsRestDemo Application Package Prefix: oracle.apps.jcs.test Application Template: Fusion Web Application (ADF) Configure Local Cloud Connection Follow the steps documented in the "Java Cloud Service ADF Web Application" article to configure a local database connection needed to create the ADFbc objects. Configure Libraries Add the 3rd party libraries into the class path. Create the following directory and copy the jar files into it: <JDEV_USER_HOME>/JcsRestDemo/lib  Select the "Model" project, navigate "Application -> Project Properties -> Libraries and Classpath -> Add JAR / Directory" and add the 2 3rd party libraries: Accessing Data from Taleo To access data from Taleo using the REST service the 3rd party libraries will be used. 2 Java classes are implemented, one representing the Candidate object and another for accessing the Taleo repository Candidate Candidate object is a POJO object used to represent the candidate data obtained from the Taleo repository. The data obtained will be used to populate the ADFbc object used to display the data on the UI. The candidate object contains simply the variables we obtain using the REST services and the getters / setters for them: Navigate "New -> General -> Java -> Java Class", enter "Candidate" as the name and create it in the package "oracle.apps.jcs.test.model".  Copy / paste the following as the content: import oracle.jbo.domain.Number; public class Candidate { private Number candId; private String firstName; private String lastName; public Candidate() { super(); } public Candidate(Number candId, String firstName, String lastName) { super(); this.candId = candId; this.firstName = firstName; this.lastName = lastName; } public void setCandId(Number candId) { this.candId = candId; } public Number getCandId() { return candId; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getFirstName() { return firstName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getLastName() { return lastName; } } Taleo Repository Taleo repository class will interact with the Taleo REST services. The logic will query data from Taleo and populate Candidate objects with the data. The Candidate object will then be used to populate the ADFbc object used to display data on the UI. Navigate "New -> General -> Java -> Java Class", enter "TaleoRepository" as the name and create it in the package "oracle.apps.jcs.test.model".  Copy / paste the following as the content (for details of the implementation refer to the documentation in the code): import com.sun.jersey.api.client.Client; import com.sun.jersey.api.client.ClientResponse; import com.sun.jersey.api.client.WebResource; import com.sun.jersey.core.util.MultivaluedMapImpl; import java.io.StringReader; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.Map; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.MultivaluedMap; import oracle.jbo.domain.Number; import org.json.simple.JSONArray; import org.json.simple.JSONObject; import org.json.simple.parser.JSONParser; /** * This class interacts with the Taleo REST services */ public class TaleoRepository { /** * Connection information needed to access the Taleo services */ String _company = null; String _userName = null; String _password = null; /** * Jersey client used to access the REST services */ Client _client = null; /** * Parser for processing the JSON objects used as * input / output for the services */ JSONParser _parser = null; /** * The base url for constructing the REST URLs. This is obtained * from Taleo with a service call */ String _baseUrl = null; /** * Authentication token obtained from Taleo using a service call. * The token can be used to authenticate on subsequent * service calls. The token will expire in 4 hours */ String _authToken = null; /** * Static url that can be used to obtain the url used to construct * service calls for a given company */ private static String _taleoUrl = "https://tbe.taleo.net/MANAGER/dispatcher/api/v1/serviceUrl/"; /** * Default constructor for the repository * Authentication details are passed as parameters and used to generate * authentication token. Note that each service call will * generate its own token. This is done to avoid dealing with the expiry * of the token. Also only 20 tokens are allowed per user simultaneously. * So instead for each call there is login / logout. * * @param company the company for which the service calls are made * @param userName the user name to authenticate with * @param password the password to authenticate with. */ public TaleoRepository(String company, String userName, String password) { super(); _company = company; _userName = userName; _password = password; _client = Client.create(); _parser = new JSONParser(); _baseUrl = getBaseUrl(); } /** * This obtains the base url for a company to be used * to construct the urls for service calls * @return base url for the service calls */ private String getBaseUrl() { String result = null; if (null != _baseUrl) { result = _baseUrl; } else { try { String company = _company; WebResource resource = _client.resource(_taleoUrl + company); ClientResponse response = resource.type(MediaType.APPLICATION_FORM_URLENCODED_TYPE).get(ClientResponse.class); String entity = response.getEntity(String.class); JSONObject jsonObject = (JSONObject)_parser.parse(new StringReader(entity)); JSONObject jsonResponse = (JSONObject)jsonObject.get("response"); result = (String)jsonResponse.get("URL"); } catch (Exception ex) { ex.printStackTrace(); } } return result; } /** * Generates authentication token, that can be used to authenticate on * subsequent service calls. Note that each service call will * generate its own token. This is done to avoid dealing with the expiry * of the token. Also only 20 tokens are allowed per user simultaneously. * So instead for each call there is login / logout. * @return authentication token that can be used to authenticate on * subsequent service calls */ private String login() { String result = null; try { MultivaluedMap<String, String> formData = new MultivaluedMapImpl(); formData.add("orgCode", _company); formData.add("userName", _userName); formData.add("password", _password); WebResource resource = _client.resource(_baseUrl + "login"); ClientResponse response = resource.type(MediaType.APPLICATION_FORM_URLENCODED_TYPE).post(ClientResponse.class, formData); String entity = response.getEntity(String.class); JSONObject jsonObject = (JSONObject)_parser.parse(new StringReader(entity)); JSONObject jsonResponse = (JSONObject)jsonObject.get("response"); result = (String)jsonResponse.get("authToken"); } catch (Exception ex) { throw new RuntimeException("Unable to login ", ex); } if (null == result) throw new RuntimeException("Unable to login "); return result; } /** * Releases a authentication token. Each call to login must be followed * by call to logout after the processing is done. This is required as * the tokens are limited to 20 per user and if not released the tokens * will only expire after 4 hours. * @param authToken */ private void logout(String authToken) { WebResource resource = _client.resource(_baseUrl + "logout"); resource.header("cookie", "authToken=" + authToken).post(ClientResponse.class); } /** * This method is used to obtain a list of candidates using a REST * service call. At this example the query is hard coded to query * based on status. The url constructed to access the service is: * <_baseUrl>/object/candidate/search.xml?status=16 * @return List of candidates obtained with the service call */ public List<Candidate> getCandidates() { List<Candidate> result = new ArrayList<Candidate>(); try { // First login, note that in finally block we must have logout _authToken = "authToken=" + login(); /** * Construct the URL, the resulting url will be: * <_baseUrl>/object/candidate/search.xml?status=16 */ MultivaluedMap<String, String> formData = new MultivaluedMapImpl(); formData.add("status", "16"); JSONArray searchResults = (JSONArray)getTaleoResource("object/candidate/search", "searchResults", formData); /** * Process the results, the resulting JSON object is something like * this (simplified for readability): * * { * "response": * { * "searchResults": * [ * { * "candidate": * { * "candId": 211, * "firstName": "Mary", * "lastName": "Stochi", * logic here will find the candidate object(s), obtain the desired * data from them, construct a Candidate object based on the data * and add it to the results. */ for (Object object : searchResults) { JSONObject temp = (JSONObject)object; JSONObject candidate = (JSONObject)findObject(temp, "candidate"); Long candIdTemp = (Long)candidate.get("candId"); Number candId = (null == candIdTemp ? null : new Number(candIdTemp)); String firstName = (String)candidate.get("firstName"); String lastName = (String)candidate.get("lastName"); result.add(new Candidate(candId, firstName, lastName)); } } catch (Exception ex) { ex.printStackTrace(); } finally { if (null != _authToken) logout(_authToken); } return result; } /** * Convenience method to construct url for the service call, invoke the * service and obtain a resource from the response * @param path the path for the service to be invoked. This is combined * with the base url to construct a url for the service * @param resource the key for the object in the response that will be * obtained * @param parameters any parameters used for the service call. The call * is slightly different depending whether parameters exist or not. * @return the resource from the response for the service call */ private Object getTaleoResource(String path, String resource, MultivaluedMap<String, String> parameters) { Object result = null; try { WebResource webResource = _client.resource(_baseUrl + path); ClientResponse response = null; if (null == parameters) response = webResource.header("cookie", _authToken).get(ClientResponse.class); else response = webResource.queryParams(parameters).header("cookie", _authToken).get(ClientResponse.class); String entity = response.getEntity(String.class); JSONObject jsonObject = (JSONObject)_parser.parse(new StringReader(entity)); result = findObject(jsonObject, resource); } catch (Exception ex) { ex.printStackTrace(); } return result; } /** * Convenience method to recursively find a object with an key * traversing down from a given root object. This will traverse a * JSONObject / JSONArray recursively to find a matching key, if found * the object with the key is returned. * @param root root object which contains the key searched for * @param key the key for the object to search for * @return the object matching the key */ private Object findObject(Object root, String key) { Object result = null; if (root instanceof JSONObject) { JSONObject rootJSON = (JSONObject)root; if (rootJSON.containsKey(key)) { result = rootJSON.get(key); } else { Iterator children = rootJSON.entrySet().iterator(); while (children.hasNext()) { Map.Entry entry = (Map.Entry)children.next(); Object child = entry.getValue(); if (child instanceof JSONObject || child instanceof JSONArray) { result = findObject(child, key); if (null != result) break; } } } } else if (root instanceof JSONArray) { JSONArray rootJSON = (JSONArray)root; for (Object child : rootJSON) { if (child instanceof JSONObject || child instanceof JSONArray) { result = findObject(child, key); if (null != result) break; } } } return result; } }   Creating Business Objects While JCS application can be created without a local database, the local database is required when using ADFbc objects even if database objects are not referred. For this example we will create a "Transient" view object that will be programmatically populated based the data obtained from Taleo REST services. Creating ADFbc objects Choose the "Model" project and navigate "New -> Business Tier : ADF Business Components : View Object". On the "Initialize Business Components Project" choose the local database connection created in previous step. On Step 1 enter "JcsRestDemoVO" on the "Name" and choose "Rows populated programmatically, not based on query": On step 2 create the following attributes: CandId Type: Number Updatable: Always Key Attribute: checked Name Type: String Updatable: Always On steps 3 and 4 accept defaults and click "Next".  On step 5 check the "Application Module" checkbox and enter "JcsRestDemoAM" as the name: Click "Finish" to generate the objects. Populating the VO To display the data on the UI the "transient VO" is populated programmatically based on the data obtained from the Taleo REST services. Open the "JcsRestDemoVOImpl.java". Copy / paste the following as the content (for details of the implementation refer to the documentation in the code): import java.sql.ResultSet; import java.util.List; import java.util.ListIterator; import oracle.jbo.server.ViewObjectImpl; import oracle.jbo.server.ViewRowImpl; import oracle.jbo.server.ViewRowSetImpl; // --------------------------------------------------------------------- // --- File generated by Oracle ADF Business Components Design Time. // --- Tue Feb 18 09:40:25 PST 2014 // --- Custom code may be added to this class. // --- Warning: Do not modify method signatures of generated methods. // --------------------------------------------------------------------- public class JcsRestDemoVOImpl extends ViewObjectImpl { /** * This is the default constructor (do not remove). */ public JcsRestDemoVOImpl() { } @Override public void executeQuery() { /** * For some reason we need to reset everything, otherwise * 2nd entry to the UI screen may fail with * "java.util.NoSuchElementException" in createRowFromResultSet * call to "candidates.next()". I am not sure why this is happening * as the Iterator is new and "hasNext" is true at the point * of the execution. My theory is that since the iterator object is * exactly the same the VO cache somehow reuses the iterator including * the pointer that has already exhausted the iterable elements on the * previous run. Working around the issue * here by cleaning out everything on the VO every time before query * is executed on the VO. */ getViewDef().setQuery(null); getViewDef().setSelectClause(null); setQuery(null); this.reset(); this.clearCache(); super.executeQuery(); } /** * executeQueryForCollection - overridden for custom java data source support. */ protected void executeQueryForCollection(Object qc, Object[] params, int noUserParams) { /** * Integrate with the Taleo REST services using TaleoRepository class. * A list of candidates matching a hard coded query is obtained. */ TaleoRepository repository = new TaleoRepository(<company>, <username>, <password>); List<Candidate> candidates = repository.getCandidates(); /** * Store iterator for the candidates as user data on the collection. * This will be used in createRowFromResultSet to create rows based on * the custom iterator. */ ListIterator<Candidate> candidatescIterator = candidates.listIterator(); setUserDataForCollection(qc, candidatescIterator); super.executeQueryForCollection(qc, params, noUserParams); } /** * hasNextForCollection - overridden for custom java data source support. */ protected boolean hasNextForCollection(Object qc) { boolean result = false; /** * Determines whether there are candidates for which to create a row */ ListIterator<Candidate> candidates = (ListIterator<Candidate>)getUserDataForCollection(qc); result = candidates.hasNext(); /** * If all candidates to be created indicate that processing is done */ if (!result) { setFetchCompleteForCollection(qc, true); } return result; } /** * createRowFromResultSet - overridden for custom java data source support. */ protected ViewRowImpl createRowFromResultSet(Object qc, ResultSet resultSet) { /** * Obtain the next candidate from the collection and create a row * for it. */ ListIterator<Candidate> candidates = (ListIterator<Candidate>)getUserDataForCollection(qc); ViewRowImpl row = createNewRowForCollection(qc); try { Candidate candidate = candidates.next(); row.setAttribute("CandId", candidate.getCandId()); row.setAttribute("Name", candidate.getFirstName() + " " + candidate.getLastName()); } catch (Exception e) { e.printStackTrace(); } return row; } /** * getQueryHitCount - overridden for custom java data source support. */ public long getQueryHitCount(ViewRowSetImpl viewRowSet) { /** * For this example this is not implemented rather we always return 0. */ return 0; } } Creating UI Choose the "ViewController" project and navigate "New -> Web Tier : JSF : JSF Page". On the "Create JSF Page" enter "JcsRestDemo" as name and ensure that the "Create as XML document (*.jspx)" is checked.  Open "JcsRestDemo.jspx" and navigate to "Data Controls -> JcsRestDemoAMDataControl -> JcsRestDemoVO1" and drag & drop the VO to the "<af:form> " as a "ADF Read-only Table": Accept the defaults in "Edit Table Columns". To execute the query navigate to to "Data Controls -> JcsRestDemoAMDataControl -> JcsRestDemoVO1 -> Operations -> Execute" and drag & drop the operation to the "<af:form> " as a "Button": Deploying to JCS Follow the same steps as documented in previous article"Java Cloud Service ADF Web Application". Once deployed the application can be accessed with URL: https://java-[identity domain].java.[data center].oraclecloudapps.com/JcsRestDemo-ViewController-context-root/faces/JcsRestDemo.jspx The UI displays a list of candidates obtained from the Taleo REST Services: Summary In this article we learned how to integrate with REST services using Jersey library in JCS. In future articles various other integration techniques will be covered.

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  • Building a better mouse-trap &ndash; Improving the creation of XML Message Requests using Reflection, XML &amp; XSLT

    - by paulschapman
    Introduction The way I previously created messages to send to the GovTalk service I used the XMLDocument to create the request. While this worked it left a number of problems; not least that for every message a special function would need to created. This is OK for the short term but the biggest cost in any software project is maintenance and this would be a headache to maintain. So the following is a somewhat better way of achieving the same thing. For the purposes of this article I am going to be using the CompanyNumberSearch request of the GovTalk service – although this technique would work for any service that accepted XML. The C# functions which send and receive the messages remain the same. The magic sauce in this is the XSLT which defines the structure of the request, and the use of objects in conjunction with reflection to provide the content. It is a bit like Sweet Chilli Sauce added to Chicken on a bed of rice. So on to the Sweet Chilli Sauce The Sweet Chilli Sauce The request to search for a company based on it’s number is as follows; <GovTalkMessage xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" > <EnvelopeVersion>1.0</EnvelopeVersion> <Header> <MessageDetails> <Class>NumberSearch</Class> <Qualifier>request</Qualifier> <TransactionID>1</TransactionID> </MessageDetails> <SenderDetails> <IDAuthentication> <SenderID>????????????????????????????????</SenderID> <Authentication> <Method>CHMD5</Method> <Value>????????????????????????????????</Value> </Authentication> </IDAuthentication> </SenderDetails> </Header> <GovTalkDetails> <Keys/> </GovTalkDetails> <Body> <NumberSearchRequest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://xmlgw.companieshouse.gov.uk/v1-0/schema/NumberSearch.xsd"> <PartialCompanyNumber>99999999</PartialCompanyNumber> <DataSet>LIVE</DataSet> <SearchRows>1</SearchRows> </NumberSearchRequest> </Body> </GovTalkMessage> This is the XML that we send to the GovTalk Service and we get back a list of companies that match the criteria passed A message is structured in two parts; The envelope which identifies the person sending the request, with the name of the request, and the body which gives the detail of the company we are looking for. The Chilli What makes it possible is the use of XSLT to define the message – and serialization to convert each request object into XML. To start we need to create an object which will represent the contents of the message we are sending. However there is a common properties in all the messages that we send to Companies House. These properties are as follows SenderId – the id of the person sending the message SenderPassword – the password associated with Id TransactionId – Unique identifier for the message AuthenticationValue – authenticates the request Because these properties are unique to the Companies House message, and because they are shared with all messages they are perfect candidates for a base class. The class is as follows; using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Security.Cryptography; using System.Text; using System.Text.RegularExpressions; using Microsoft.WindowsAzure.ServiceRuntime; namespace CompanyHub.Services { public class GovTalkRequest { public GovTalkRequest() { try { SenderID = RoleEnvironment.GetConfigurationSettingValue("SenderId"); SenderPassword = RoleEnvironment.GetConfigurationSettingValue("SenderPassword"); TransactionId = DateTime.Now.Ticks.ToString(); AuthenticationValue = EncodePassword(String.Format("{0}{1}{2}", SenderID, SenderPassword, TransactionId)); } catch (System.Exception ex) { throw ex; } } /// <summary> /// returns the Sender ID to be used when communicating with the GovTalk Service /// </summary> public String SenderID { get; set; } /// <summary> /// return the password to be used when communicating with the GovTalk Service /// </summary> public String SenderPassword { get; set; } // end SenderPassword /// <summary> /// Transaction Id - uses the Time and Date converted to Ticks /// </summary> public String TransactionId { get; set; } // end TransactionId /// <summary> /// calculate the authentication value that will be used when /// communicating with /// </summary> public String AuthenticationValue { get; set; } // end AuthenticationValue property /// <summary> /// encodes password(s) using MD5 /// </summary> /// <param name="clearPassword"></param> /// <returns></returns> public static String EncodePassword(String clearPassword) { MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider(); byte[] hashedBytes; UTF32Encoding encoder = new UTF32Encoding(); hashedBytes = md5Hasher.ComputeHash(ASCIIEncoding.Default.GetBytes(clearPassword)); String result = Regex.Replace(BitConverter.ToString(hashedBytes), "-", "").ToLower(); return result; } } } There is nothing particularly clever here, except for the EncodePassword method which hashes the value made up of the SenderId, Password and Transaction id. Each message inherits from this object. So for the Company Number Search in addition to the properties above we need a partial number, which dataset to search – for the purposes of the project we only need to search the LIVE set so this can be set in the constructor and the SearchRows. Again all are set as properties. With the SearchRows and DataSet initialized in the constructor. public class CompanyNumberSearchRequest : GovTalkRequest, IDisposable { /// <summary> /// /// </summary> public CompanyNumberSearchRequest() : base() { DataSet = "LIVE"; SearchRows = 1; } /// <summary> /// Company Number to search against /// </summary> public String PartialCompanyNumber { get; set; } /// <summary> /// What DataSet should be searched for the company /// </summary> public String DataSet { get; set; } /// <summary> /// How many rows should be returned /// </summary> public int SearchRows { get; set; } public void Dispose() { DataSet = String.Empty; PartialCompanyNumber = String.Empty; DataSet = "LIVE"; SearchRows = 1; } } As well as inheriting from our base class, I have also inherited from IDisposable – not just because it is just plain good practice to dispose of objects when coding, but it gives also gives us more versatility when using the object. There are four stages in making a request and this is reflected in the four methods we execute in making a call to the Companies House service; Create a request Send a request Check the status If OK then get the results of the request I’ve implemented each of these stages within a static class called Toolbox – which also means I don’t need to create an instance of the class to use it. When making a request there are three stages; Get the template for the message Serialize the object representing the message Transform the serialized object using a predefined XSLT file. Each of my templates I have defined as an embedded resource. When retrieving a resource of this kind we have to include the full namespace to the resource. In making the code re-usable as much as possible I defined the full ‘path’ within the GetRequest method. requestFile = String.Format("CompanyHub.Services.Schemas.{0}", RequestFile); So we now have the full path of the file within the assembly. Now all we need do is retrieve the assembly and get the resource. asm = Assembly.GetExecutingAssembly(); sr = asm.GetManifestResourceStream(requestFile); Once retrieved  So this can be returned to the calling function and we now have a stream of XSLT to define the message. Time now to serialize the request to create the other side of this message. // Serialize object containing Request, Load into XML Document t = Obj.GetType(); ms = new MemoryStream(); serializer = new XmlSerializer(t); xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII); serializer.Serialize(xmlTextWriter, Obj); ms = (MemoryStream)xmlTextWriter.BaseStream; GovTalkRequest = Toolbox.ConvertByteArrayToString(ms.ToArray()); First off we need the type of the object so we make a call to the GetType method of the object containing the Message properties. Next we need a MemoryStream, XmlSerializer and an XMLTextWriter so these can be initialized. The object is serialized by making the call to the Serialize method of the serializer object. The result of that is then converted into a MemoryStream. That MemoryStream is then converted into a string. ConvertByteArrayToString This is a fairly simple function which uses an ASCIIEncoding object found within the System.Text namespace to convert an array of bytes into a string. public static String ConvertByteArrayToString(byte[] bytes) { System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding(); return enc.GetString(bytes); } I only put it into a function because I will be using this in various places. The Sauce When adding support for other messages outside of creating a new object to store the properties of the message, the C# components do not need to change. It is in the XSLT file that the versatility of the technique lies. The XSLT file determines the format of the message. For the CompanyNumberSearch the XSLT file is as follows; <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/"> <GovTalkMessage xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" > <EnvelopeVersion>1.0</EnvelopeVersion> <Header> <MessageDetails> <Class>NumberSearch</Class> <Qualifier>request</Qualifier> <TransactionID> <xsl:value-of select="CompanyNumberSearchRequest/TransactionId"/> </TransactionID> </MessageDetails> <SenderDetails> <IDAuthentication> <SenderID><xsl:value-of select="CompanyNumberSearchRequest/SenderID"/></SenderID> <Authentication> <Method>CHMD5</Method> <Value> <xsl:value-of select="CompanyNumberSearchRequest/AuthenticationValue"/> </Value> </Authentication> </IDAuthentication> </SenderDetails> </Header> <GovTalkDetails> <Keys/> </GovTalkDetails> <Body> <NumberSearchRequest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://xmlgw.companieshouse.gov.uk/v1-0/schema/NumberSearch.xsd"> <PartialCompanyNumber> <xsl:value-of select="CompanyNumberSearchRequest/PartialCompanyNumber"/> </PartialCompanyNumber> <DataSet> <xsl:value-of select="CompanyNumberSearchRequest/DataSet"/> </DataSet> <SearchRows> <xsl:value-of select="CompanyNumberSearchRequest/SearchRows"/> </SearchRows> </NumberSearchRequest> </Body> </GovTalkMessage> </xsl:template> </xsl:stylesheet> The outer two tags define that this is a XSLT stylesheet and the root tag from which the nodes are searched for. The GovTalkMessage is the format of the message that will be sent to Companies House. We first set up the XslCompiledTransform object which will transform the XSLT template and the serialized object into the request to Companies House. xslt = new XslCompiledTransform(); resultStream = new MemoryStream(); writer = new XmlTextWriter(resultStream, Encoding.ASCII); doc = new XmlDocument(); The Serialize method require XmlTextWriter to write the XML (writer) and a stream to place the transferred object into (writer). The XML will be loaded into an XMLDocument object (doc) prior to the transformation. // create XSLT Template xslTemplate = Toolbox.GetRequest(Template); xslTemplate.Seek(0, SeekOrigin.Begin); templateReader = XmlReader.Create(xslTemplate); xslt.Load(templateReader); I have stored all the templates as a series of Embedded Resources and the GetRequestCall takes the name of the template and extracts the relevent XSLT file. /// <summary> /// Gets the framwork XML which makes the request /// </summary> /// <param name="RequestFile"></param> /// <returns></returns> public static Stream GetRequest(String RequestFile) { String requestFile = String.Empty; Stream sr = null; Assembly asm = null; try { requestFile = String.Format("CompanyHub.Services.Schemas.{0}", RequestFile); asm = Assembly.GetExecutingAssembly(); sr = asm.GetManifestResourceStream(requestFile); } catch (Exception) { throw; } finally { asm = null; } return sr; } // end private static stream GetRequest We first take the template name and expand it to include the full namespace to the Embedded Resource I like to keep all my schemas in the same directory and so the namespace reflects this. The rest is the default namespace for the project. Then we get the currently executing assembly (which will contain the resources with the call to GetExecutingAssembly() ) Finally we get a stream which contains the XSLT file. We use this stream and then load an XmlReader with the contents of the template, and that is in turn loaded into the XslCompiledTransform object. We convert the object containing the message properties into Xml by serializing it; calling the Serialize() method of the XmlSerializer object. To set up the object we do the following; t = Obj.GetType(); ms = new MemoryStream(); serializer = new XmlSerializer(t); xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII); We first determine the type of the object being transferred by calling GetType() We create an XmlSerializer object by passing the type of the object being serialized. The serializer writes to a memory stream and that is linked to an XmlTextWriter. Next job is to serialize the object and load it into an XmlDocument. serializer.Serialize(xmlTextWriter, Obj); ms = (MemoryStream)xmlTextWriter.BaseStream; xmlRequest = new XmlTextReader(ms); GovTalkRequest = Toolbox.ConvertByteArrayToString(ms.ToArray()); doc.LoadXml(GovTalkRequest); Time to transform the XML to construct the full request. xslt.Transform(doc, writer); resultStream.Seek(0, SeekOrigin.Begin); request = Toolbox.ConvertByteArrayToString(resultStream.ToArray()); So that creates the full request to be sent  to Companies House. Sending the request So far we have a string with a request for the Companies House service. Now we need to send the request to the Companies House Service. Configuration within an Azure project There are entire blog entries written about configuration within an Azure project – most of this is out of scope for this article but the following is a summary. Configuration is defined in two files within the parent project *.csdef which contains the definition of configuration setting. <?xml version="1.0" encoding="utf-8"?> <ServiceDefinition name="OnlineCompanyHub" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition"> <WebRole name="CompanyHub.Host"> <InputEndpoints> <InputEndpoint name="HttpIn" protocol="http" port="80" /> </InputEndpoints> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" /> <Setting name="DataConnectionString" /> </ConfigurationSettings> </WebRole> <WebRole name="CompanyHub.Services"> <InputEndpoints> <InputEndpoint name="HttpIn" protocol="http" port="8080" /> </InputEndpoints> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" /> <Setting name="SenderId"/> <Setting name="SenderPassword" /> <Setting name="GovTalkUrl"/> </ConfigurationSettings> </WebRole> <WorkerRole name="CompanyHub.Worker"> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" /> </ConfigurationSettings> </WorkerRole> </ServiceDefinition>   Above is the configuration definition from the project. What we are interested in however is the ConfigurationSettings tag of the CompanyHub.Services WebRole. There are four configuration settings here, but at the moment we are interested in the second to forth settings; SenderId, SenderPassword and GovTalkUrl The value of these settings are defined in the ServiceDefinition.cscfg file; <?xml version="1.0"?> <ServiceConfiguration serviceName="OnlineCompanyHub" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration"> <Role name="CompanyHub.Host"> <Instances count="2" /> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" /> <Setting name="DataConnectionString" value="UseDevelopmentStorage=true" /> </ConfigurationSettings> </Role> <Role name="CompanyHub.Services"> <Instances count="2" /> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" /> <Setting name="SenderId" value="UserID"/> <Setting name="SenderPassword" value="Password"/> <Setting name="GovTalkUrl" value="http://xmlgw.companieshouse.gov.uk/v1-0/xmlgw/Gateway"/> </ConfigurationSettings> </Role> <Role name="CompanyHub.Worker"> <Instances count="2" /> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" /> </ConfigurationSettings> </Role> </ServiceConfiguration>   Look for the Role tag that contains our project name (CompanyHub.Services). Having configured the parameters we can now transmit the request. This is done by ‘POST’ing a stream of XML to the Companies House servers. govTalkUrl = RoleEnvironment.GetConfigurationSettingValue("GovTalkUrl"); request = WebRequest.Create(govTalkUrl); request.Method = "POST"; request.ContentType = "text/xml"; writer = new StreamWriter(request.GetRequestStream()); writer.WriteLine(RequestMessage); writer.Close(); We use the WebRequest object to send the object. Set the method of sending to ‘POST’ and the type of data as text/xml. Once set up all we do is write the request to the writer – this sends the request to Companies House. Did the Request Work Part I – Getting the response Having sent a request – we now need the result of that request. response = request.GetResponse(); reader = response.GetResponseStream(); result = Toolbox.ConvertByteArrayToString(Toolbox.ReadFully(reader));   The WebRequest object has a GetResponse() method which allows us to get the response sent back. Like many of these calls the results come in the form of a stream which we convert into a string. Did the Request Work Part II – Translating the Response Much like XSLT and XML were used to create the original request, so it can be used to extract the response and by deserializing the result we create an object that contains the response. Did it work? It would be really great if everything worked all the time. Of course if it did then I don’t suppose people would pay me and others the big bucks so that our programmes do not a) Collapse in a heap (this is an area of memory) b) Blow every fuse in the place in a shower of sparks (this will probably not happen this being real life and not a Hollywood movie, but it was possible to blow the sound system of a BBC Model B with a poorly coded setting) c) Go nuts and trap everyone outside the airlock (this was from a movie, and unless NASA get a manned moon/mars mission set up unlikely to happen) d) Go nuts and take over the world (this was also from a movie, but please note life has a habit of being of exceeding the wildest imaginations of Hollywood writers (note writers – Hollywood executives have no imagination and judging by recent output of that town have turned plagiarism into an art form). e) Freeze in total confusion because the cleaner pulled the plug to the internet router (this has happened) So anyway – we need to check to see if our request actually worked. Within the GovTalk response there is a section that details the status of the message and a description of what went wrong (if anything did). I have defined an XSLT template which will extract these into an XML document. <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:ev="http://www.govtalk.gov.uk/CM/envelope" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <xsl:template match="/"> <GovTalkStatus xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Status> <xsl:value-of select="ev:GovTalkMessage/ev:Header/ev:MessageDetails/ev:Qualifier"/> </Status> <Text> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Text"/> </Text> <Location> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Location"/> </Location> <Number> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Number"/> </Number> <Type> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Type"/> </Type> </GovTalkStatus> </xsl:template> </xsl:stylesheet>   Only thing different about previous XSL files is the references to two namespaces ev & gt. These are defined in the GovTalk response at the top of the response; xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" If we do not put these references into the XSLT template then  the XslCompiledTransform object will not be able to find the relevant tags. Deserialization is a fairly simple activity. encoder = new ASCIIEncoding(); ms = new MemoryStream(encoder.GetBytes(statusXML)); serializer = new XmlSerializer(typeof(GovTalkStatus)); xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII); messageStatus = (GovTalkStatus)serializer.Deserialize(ms);   We set up a serialization object using the object type containing the error state and pass to it the results of a transformation between the XSLT above and the GovTalk response. Now we have an object containing any error state, and the error message. All we need to do is check the status. If there is an error then we can flag an error. If not then  we extract the results and pass that as an object back to the calling function. We go this by guess what – defining an XSLT template for the result and using that to create an Xml Stream which can be deserialized into a .Net object. In this instance the XSLT to create the result of a Company Number Search is; <?xml version="1.0" encoding="us-ascii"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:ev="http://www.govtalk.gov.uk/CM/envelope" xmlns:sch="http://xmlgw.companieshouse.gov.uk/v1-0/schema" exclude-result-prefixes="ev"> <xsl:template match="/"> <CompanySearchResult xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <CompanyNumber> <xsl:value-of select="ev:GovTalkMessage/ev:Body/sch:NumberSearch/sch:CoSearchItem/sch:CompanyNumber"/> </CompanyNumber> <CompanyName> <xsl:value-of select="ev:GovTalkMessage/ev:Body/sch:NumberSearch/sch:CoSearchItem/sch:CompanyName"/> </CompanyName> </CompanySearchResult> </xsl:template> </xsl:stylesheet> and the object definition is; using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace CompanyHub.Services { public class CompanySearchResult { public CompanySearchResult() { CompanyNumber = String.Empty; CompanyName = String.Empty; } public String CompanyNumber { get; set; } public String CompanyName { get; set; } } } Our entire code to make calls to send a request, and interpret the results are; String request = String.Empty; String response = String.Empty; GovTalkStatus status = null; fault = null; try { using (CompanyNumberSearchRequest requestObj = new CompanyNumberSearchRequest()) { requestObj.PartialCompanyNumber = CompanyNumber; request = Toolbox.CreateRequest(requestObj, "CompanyNumberSearch.xsl"); response = Toolbox.SendGovTalkRequest(request); status = Toolbox.GetMessageStatus(response); if (status.Status.ToLower() == "error") { fault = new HubFault() { Message = status.Text }; } else { Object obj = Toolbox.GetGovTalkResponse(response, "CompanyNumberSearchResult.xsl", typeof(CompanySearchResult)); } } } catch (FaultException<ArgumentException> ex) { fault = new HubFault() { FaultType = ex.Detail.GetType().FullName, Message = ex.Detail.Message }; } catch (System.Exception ex) { fault = new HubFault() { FaultType = ex.GetType().FullName, Message = ex.Message }; } finally { } Wrap up So there we have it – a reusable set of functions to send and interpret XML results from an internet based service. The code is reusable with a little change with any service which uses XML as a transport mechanism – and as for the Companies House GovTalk service all I need to do is create various objects for the result and message sent and the relevent XSLT files. I might need minor changes for other services but something like 70-90% will be exactly the same.

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  • A first look at ConfORM - Part 1

    - by thangchung
    All source codes for this post can be found at here.Have you ever heard of ConfORM is not? I have read it three months ago when I wrote an post about NHibernate and Autofac. At that time, this project really has just started and still in beta version, so I still do not really care much. But recently when reading a book by Jason Dentler NHibernate 3.0 Cookbook, I started to pay attention to it. Author have mentioned quite a lot of OSS in his book. And now again I have reviewed ConfORM once again. I have been involved in ConfORM development group on google and read some articles about it. Fabio Maulo spent a lot of work for the OSS, and I hope it will adapt a great way for NHibernate (because he contributed to NHibernate that). So what is ConfORM? It is stand for Configuration ORM, and it was trying to use a lot of heuristic model for identifying entities from C# code. Today, it's mostly Model First Driven development, so the first thing is to build the entity model. This is really important and we can see it is the heart of business software. Then we have to tell DB about the entity of this model. We often will use Inversion Engineering here, Database Schema is will create based on recently Entity Model. From now we will absolutely not interested in the DB again, only focus on the Entity Model.Fluent NHibenate really good, I liked this OSS. Sharp Architecture and has done so well in Fluent NHibernate integration with applications. A Multiple Database technical in Sharp Architecture is truly awesome. It can receive configuration, a connection string and a dll containing entity model, which would then create a SessionFactory, finally caching inside the computer memory. As the number of SessionFactory can be very large and will full of the memory, it has also devised a way of caching SessionFactory in the file. This post I hope this will not completely explain about and building a model of multiple databases. I just tried to mount a number of posts from the community and apply some of my knowledge to build a management model Session for ConfORM.As well as Fluent NHibernate, ConfORM also supported on the interface mapping, see this to understand it. So the first thing we will build the Entity Model for it, and here is what I will use the model for this article. A simple model for managing news and polls, it will be too easy for a number of people, but I hope not to bring complexity to this post.I will then have some code to build super type for the Entity Model. public interface IEntity<TId>    {        TId Id { get; set; }    } public abstract class EntityBase<TId> : IEntity<TId>    {        public virtual TId Id { get; set; }         public override bool Equals(object obj)        {            return Equals(obj as EntityBase<TId>);        }         private static bool IsTransient(EntityBase<TId> obj)        {            return obj != null &&            Equals(obj.Id, default(TId));        }         private Type GetUnproxiedType()        {            return GetType();        }         public virtual bool Equals(EntityBase<TId> other)        {            if (other == null)                return false;            if (ReferenceEquals(this, other))                return true;            if (!IsTransient(this) &&            !IsTransient(other) &&            Equals(Id, other.Id))            {                var otherType = other.GetUnproxiedType();                var thisType = GetUnproxiedType();                return thisType.IsAssignableFrom(otherType) ||                otherType.IsAssignableFrom(thisType);            }            return false;        }         public override int GetHashCode()        {            if (Equals(Id, default(TId)))                return base.GetHashCode();            return Id.GetHashCode();        }    } Database schema will be created as:The next step is to build the ConORM builder to create a NHibernate Configuration. Patrick have a excellent article about it at here. Contract of it below: public interface IConfigBuilder    {        Configuration BuildConfiguration(string connectionString, string sessionFactoryName);    } The idea here is that I will pass in a connection string and a set of the DLL containing the Entity Model and it makes me a NHibernate Configuration (shame that I stole this ideas of Sharp Architecture). And here is its code: public abstract class ConfORMConfigBuilder : RootObject, IConfigBuilder    {        private static IConfigurator _configurator;         protected IEnumerable<Type> DomainTypes;         private readonly IEnumerable<string> _assemblies;         protected ConfORMConfigBuilder(IEnumerable<string> assemblies)            : this(new Configurator(), assemblies)        {            _assemblies = assemblies;        }         protected ConfORMConfigBuilder(IConfigurator configurator, IEnumerable<string> assemblies)        {            _configurator = configurator;            _assemblies = assemblies;        }         public abstract void GetDatabaseIntegration(IDbIntegrationConfigurationProperties dBIntegration, string connectionString);         protected abstract HbmMapping GetMapping();         public Configuration BuildConfiguration(string connectionString, string sessionFactoryName)        {            Contract.Requires(!string.IsNullOrEmpty(connectionString), "ConnectionString is null or empty");            Contract.Requires(!string.IsNullOrEmpty(sessionFactoryName), "SessionFactory name is null or empty");            Contract.Requires(_configurator != null, "Configurator is null");             return CatchExceptionHelper.TryCatchFunction(                () =>                {                    DomainTypes = GetTypeOfEntities(_assemblies);                     if (DomainTypes == null)                        throw new Exception("Type of domains is null");                     var configure = new Configuration();                    configure.SessionFactoryName(sessionFactoryName);                     configure.Proxy(p => p.ProxyFactoryFactory<ProxyFactoryFactory>());                    configure.DataBaseIntegration(db => GetDatabaseIntegration(db, connectionString));                     if (_configurator.GetAppSettingString("IsCreateNewDatabase").ConvertToBoolean())                    {                        configure.SetProperty("hbm2ddl.auto", "create-drop");                    }                     configure.Properties.Add("default_schema", _configurator.GetAppSettingString("DefaultSchema"));                    configure.AddDeserializedMapping(GetMapping(),                                                     _configurator.GetAppSettingString("DocumentFileName"));                     SchemaMetadataUpdater.QuoteTableAndColumns(configure);                     return configure;                }, Logger);        }         protected IEnumerable<Type> GetTypeOfEntities(IEnumerable<string> assemblies)        {            var type = typeof(EntityBase<Guid>);            var domainTypes = new List<Type>();             foreach (var assembly in assemblies)            {                var realAssembly = Assembly.LoadFrom(assembly);                 if (realAssembly == null)                    throw new NullReferenceException();                 domainTypes.AddRange(realAssembly.GetTypes().Where(                    t =>                    {                        if (t.BaseType != null)                            return string.Compare(t.BaseType.FullName,                                          type.FullName) == 0;                        return false;                    }));            }             return domainTypes;        }    } I do not want to dependency on any RDBMS, so I made a builder as an abstract class, and so I will create a concrete instance for SQL Server 2008 as follows: public class SqlServerConfORMConfigBuilder : ConfORMConfigBuilder    {        public SqlServerConfORMConfigBuilder(IEnumerable<string> assemblies)            : base(assemblies)        {        }         public override void GetDatabaseIntegration(IDbIntegrationConfigurationProperties dBIntegration, string connectionString)        {            dBIntegration.Dialect<MsSql2008Dialect>();            dBIntegration.Driver<SqlClientDriver>();            dBIntegration.KeywordsAutoImport = Hbm2DDLKeyWords.AutoQuote;            dBIntegration.IsolationLevel = IsolationLevel.ReadCommitted;            dBIntegration.ConnectionString = connectionString;            dBIntegration.LogSqlInConsole = true;            dBIntegration.Timeout = 10;            dBIntegration.LogFormatedSql = true;            dBIntegration.HqlToSqlSubstitutions = "true 1, false 0, yes 'Y', no 'N'";        }         protected override HbmMapping GetMapping()        {            var orm = new ObjectRelationalMapper();             orm.Patterns.PoidStrategies.Add(new GuidPoidPattern());             var patternsAppliers = new CoolPatternsAppliersHolder(orm);            //patternsAppliers.Merge(new DatePropertyByNameApplier()).Merge(new MsSQL2008DateTimeApplier());            patternsAppliers.Merge(new ManyToOneColumnNamingApplier());            patternsAppliers.Merge(new OneToManyKeyColumnNamingApplier(orm));             var mapper = new Mapper(orm, patternsAppliers);             var entities = new List<Type>();             DomainDefinition(orm);            Customize(mapper);             entities.AddRange(DomainTypes);             return mapper.CompileMappingFor(entities);        }         private void DomainDefinition(IObjectRelationalMapper orm)        {            orm.TablePerClassHierarchy(new[] { typeof(EntityBase<Guid>) });            orm.TablePerClass(DomainTypes);             orm.OneToOne<News, Poll>();            orm.ManyToOne<Category, News>();             orm.Cascade<Category, News>(Cascade.All);            orm.Cascade<News, Poll>(Cascade.All);            orm.Cascade<User, Poll>(Cascade.All);        }         private static void Customize(Mapper mapper)        {            CustomizeRelations(mapper);            CustomizeTables(mapper);            CustomizeColumns(mapper);        }         private static void CustomizeRelations(Mapper mapper)        {        }         private static void CustomizeTables(Mapper mapper)        {        }         private static void CustomizeColumns(Mapper mapper)        {            mapper.Class<Category>(                cm =>                {                    cm.Property(x => x.Name, m => m.NotNullable(true));                    cm.Property(x => x.CreatedDate, m => m.NotNullable(true));                });             mapper.Class<News>(                cm =>                {                    cm.Property(x => x.Title, m => m.NotNullable(true));                    cm.Property(x => x.ShortDescription, m => m.NotNullable(true));                    cm.Property(x => x.Content, m => m.NotNullable(true));                });             mapper.Class<Poll>(                cm =>                {                    cm.Property(x => x.Value, m => m.NotNullable(true));                    cm.Property(x => x.VoteDate, m => m.NotNullable(true));                    cm.Property(x => x.WhoVote, m => m.NotNullable(true));                });             mapper.Class<User>(                cm =>                {                    cm.Property(x => x.UserName, m => m.NotNullable(true));                    cm.Property(x => x.Password, m => m.NotNullable(true));                });        }    } As you can see that we can do so many things in this class, such as custom entity relationships, custom binding on the columns, custom table name, ... Here I only made two so-Appliers for OneToMany and ManyToOne relationships, you can refer to it here public class ManyToOneColumnNamingApplier : IPatternApplier<PropertyPath, IManyToOneMapper>    {        #region IPatternApplier<PropertyPath,IManyToOneMapper> Members         public void Apply(PropertyPath subject, IManyToOneMapper applyTo)        {            applyTo.Column(subject.ToColumnName() + "Id");        }         #endregion         #region IPattern<PropertyPath> Members         public bool Match(PropertyPath subject)        {            return subject != null;        }         #endregion    } public class OneToManyKeyColumnNamingApplier : OneToManyPattern, IPatternApplier<PropertyPath, ICollectionPropertiesMapper>    {        public OneToManyKeyColumnNamingApplier(IDomainInspector domainInspector) : base(domainInspector) { }         #region Implementation of IPattern<PropertyPath>         public bool Match(PropertyPath subject)        {            return Match(subject.LocalMember);        }         #endregion Implementation of IPattern<PropertyPath>         #region Implementation of IPatternApplier<PropertyPath,ICollectionPropertiesMapper>         public void Apply(PropertyPath subject, ICollectionPropertiesMapper applyTo)        {            applyTo.Key(km => km.Column(GetKeyColumnName(subject)));        }         #endregion Implementation of IPatternApplier<PropertyPath,ICollectionPropertiesMapper>         protected virtual string GetKeyColumnName(PropertyPath subject)        {            Type propertyType = subject.LocalMember.GetPropertyOrFieldType();            Type childType = propertyType.DetermineCollectionElementType();            var entity = subject.GetContainerEntity(DomainInspector);            var parentPropertyInChild = childType.GetFirstPropertyOfType(entity);            var baseName = parentPropertyInChild == null ? subject.PreviousPath == null ? entity.Name : entity.Name + subject.PreviousPath : parentPropertyInChild.Name;            return GetKeyColumnName(baseName);        }         protected virtual string GetKeyColumnName(string baseName)        {            return string.Format("{0}Id", baseName);        }    } Everyone also can download the ConfORM source at google code and see example inside it. Next part I will write about multiple database factory. Hope you enjoy about it. happy coding and see you next part.

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  • Class Mapping Error: 'T' must be a non-abstract type with a public parameterless constructor

    - by Amit Ranjan
    Hi, While mapping class i am getting error 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. Below is my SqlReaderBase Class public abstract class SqlReaderBase<T> : ConnectionProvider { #region Abstract Methods protected abstract string commandText { get; } protected abstract CommandType commandType { get; } protected abstract Collection<IDataParameter> GetParameters(IDbCommand command); **protected abstract MapperBase<T> GetMapper();** #endregion #region Non Abstract Methods /// <summary> /// Method to Execute Select Queries for Retrieveing List of Result /// </summary> /// <returns></returns> public Collection<T> ExecuteReader() { //Collection of Type on which Template is applied Collection<T> collection = new Collection<T>(); // initializing connection using (IDbConnection connection = GetConnection()) { try { // creates command for sql operations IDbCommand command = connection.CreateCommand(); // assign connection to command command.Connection = connection; // assign query command.CommandText = commandText; //state what type of query is used, text, table or Sp command.CommandType = commandType; // retrieves parameter from IDataParameter Collection and assigns it to command object foreach (IDataParameter param in GetParameters(command)) command.Parameters.Add(param); // Establishes connection with database server connection.Open(); // Since it is designed for executing Select statements that will return a list of results // so we will call command's execute reader method that return a Forward Only reader with // list of results inside. using (IDataReader reader = command.ExecuteReader()) { try { // Call to Mapper Class of the template to map the data to its // respective fields MapperBase<T> mapper = GetMapper(); collection = mapper.MapAll(reader); } catch (Exception ex) // catch exception { throw ex; // log errr } finally { reader.Close(); reader.Dispose(); } } } catch (Exception ex) { throw ex; } finally { connection.Close(); connection.Dispose(); } } return collection; } #endregion } What I am trying to do is , I am executine some command and filling my class dynamically. The class is given below: namespace FooZo.Core { public class Restaurant { #region Private Member Variables private int _restaurantId = 0; private string _email = string.Empty; private string _website = string.Empty; private string _name = string.Empty; private string _address = string.Empty; private string _phone = string.Empty; private bool _hasMenu = false; private string _menuImagePath = string.Empty; private int _cuisine = 0; private bool _hasBar = false; private bool _hasHomeDelivery = false; private bool _hasDineIn = false; private int _type = 0; private string _restaurantImagePath = string.Empty; private string _serviceAvailableTill = string.Empty; private string _serviceAvailableFrom = string.Empty; public string Name { get { return _name; } set { _name = value; } } public string Address { get { return _address; } set { _address = value; } } public int RestaurantId { get { return _restaurantId; } set { _restaurantId = value; } } public string Website { get { return _website; } set { _website = value; } } public string Email { get { return _email; } set { _email = value; } } public string Phone { get { return _phone; } set { _phone = value; } } public bool HasMenu { get { return _hasMenu; } set { _hasMenu = value; } } public string MenuImagePath { get { return _menuImagePath; } set { _menuImagePath = value; } } public string RestaurantImagePath { get { return _restaurantImagePath; } set { _restaurantImagePath = value; } } public int Type { get { return _type; } set { _type = value; } } public int Cuisine { get { return _cuisine; } set { _cuisine = value; } } public bool HasBar { get { return _hasBar; } set { _hasBar = value; } } public bool HasHomeDelivery { get { return _hasHomeDelivery; } set { _hasHomeDelivery = value; } } public bool HasDineIn { get { return _hasDineIn; } set { _hasDineIn = value; } } public string ServiceAvailableFrom { get { return _serviceAvailableFrom; } set { _serviceAvailableFrom = value; } } public string ServiceAvailableTill { get { return _serviceAvailableTill; } set { _serviceAvailableTill = value; } } #endregion public Restaurant() { } } } For filling my class properties dynamically i have another class called MapperBase Class with following methods: public abstract class MapperBase<T> where T : new() { protected T Map(IDataRecord record) { T instance = new T(); string fieldName; PropertyInfo[] properties = typeof(T).GetProperties(); for (int i = 0; i < record.FieldCount; i++) { fieldName = record.GetName(i); foreach (PropertyInfo property in properties) { if (property.Name == fieldName) { property.SetValue(instance, record[i], null); } } } return instance; } public Collection<T> MapAll(IDataReader reader) { Collection<T> collection = new Collection<T>(); while (reader.Read()) { collection.Add(Map(reader)); } return collection; } } There is another class which inherits the SqlreaderBaseClass called DefaultSearch. Code is below public class DefaultSearch: SqlReaderBase<Restaurant> { protected override string commandText { get { return "Select Name from vw_Restaurants"; } } protected override CommandType commandType { get { return CommandType.Text; } } protected override Collection<IDataParameter> GetParameters(IDbCommand command) { Collection<IDataParameter> parameters = new Collection<IDataParameter>(); parameters.Clear(); return parameters; } protected override MapperBase<Restaurant> GetMapper() { MapperBase<Restaurant> mapper = new RMapper(); return mapper; } } But whenever I tried to build , I am getting error 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. Even T here is Restaurant has a Parameterless Public constructor.

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  • C# .Net 3.5 Asynchronous Socket Server Performance Problem

    - by iBrAaAa
    I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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