modulexcite / wcfex

Yet another WCF extensions library

WcfEx

Yet another lightweight WCF extensions library for .NET 4.0+

###PM> Install-Package WcfEx###

Please check out the wiki.

Features:

• Generic client channel wrappers for simplex and duplex contracts
• A generic WCF host executable for DLL-based services, optionally installed as a Windows service
• A UDP transport layer, for input/output and request/reply channels
• An in-process transport layer and automatic client host, for configuration-based hosting within the client process
• GZip/Deflate message encoders, for compressing buffered or streamed messages
• Base classes for the WCF bindings, channels, listeners, factories, and behaviors with default sync or async methods
• Synchronous and asynchronous IAsyncResult implementation utilities, for simplified Asynchronous Programming Model (APM) implementation in WCF

###Client Channel Wrappers### These generic classes simplify the development of WCF clients by removing the need for IDE-generated wrappers, which do nothing but duplicate the contract methods and delegate to the service interface. Simply instantiate a new instance of Client or DuplexClient and call the interface directly through the Server property.

// default configuration-based endpoint
using (var client = new WcfEx.Client<IService>()
   client.Server.Execute("test");

// named configuration-based endpoint
using (var client = new WcfEx.Client<IService>("MyEndpoint")
   client.Server.Execute("test");

// explicitly configured endpoint
using (var client = new WcfEx.Client<IService>(new NetNamedPipeBinding(), "net.pipe://localhost/Test"))
   client.Server.Execute("test");

###WCF Host Application### This project includes a generic Windows application (WcfExHost.exe) that can be used to host WCF DLL services created via the WCF Service Application project template. It is a lightweight alternative to IIS/WAS hosting.

Simply deploy WcfExHost.exe in the same directory as your service, and start the executable. It will load any .dll.config files in that directory and create a WCF ServiceHost instance for each configured service.

You may also register the host to run as a Windows service, using InstallUtil. The name of the Windows service is customizable via install parameters.

###UDP Transport Layer### Of course, no WCF library would not be complete without the requisite UDP transport binding. However, this version goes a bit further than the MSDN samples, including full IPV6 support and a fully re-entrant request channel that optimizes one-way requests by not sending reply messages. The UDP transport layer is also fully compatible with the composite duplex and reliable transport bindings.

###Automatic Hosting and the In-Process Transport Layer### Occasionally, it is necessary to host a WCF service within the client process, when implementing a mocked version of the service for testing, for example. However, using the ServiceHost directly within the client application couples the client to that implementation. Ideally, embedding the service host or mock in the client could be done tranparently via configuration.

WcfEx provides this with the ClientHostBehavior extension. When this behavior is added to a client endpoint, it automatically starts a host for the configured service when the client channel is first created.

<system.serviceModel>
   <extensions>
      <behaviorExtensions>
         <add name="clientHost" type="WcfEx.ClientHostBehavior,WcfEx"/>
      </behaviorExtensions>
   </extensions>
   <services>
      <service name="MyMockService">
         <endpoint contract="IMyService">...</endpoint>
      </service>
   </services>
   <client>
      <endpoint contract="IMyService">...</endpoint>
   </client>
   <behaviors>
      <endpointBehaviors>
         <behavior>
            <clientHost/>
         </behavior>
      </endpointBehaviors>
   </behaviors>
</system.serviceModel>

In addition, the library includes the <inProcTransport> binding that bypasses the system networking infrastructure and WCF encoding stack, transferring messages directly between the client and service within the same process. This is useful both for testing the service and for planning deployment flexibility without committing to a remote service installation. Because it bypasses the encoding layer, the in-process transport also performs significantly (10% in tests) better than even the named pipe transport.

###Compression Encodings### The WcfEx library includes GZip/deflate message encoders for compressing WCF messages before sending them to transport. The compression encoders work with both buffered and streamed messages.

###WCF Base Classes### Frequently when using WCF, it is necessary to extend the framework with custom functionality using the extension interfaces. However, implementing custom channel stacks and behaviors is tedious, particularly the Begin/End APM methods.

WcfEx includes an extensive library of base classes to ease the implementation and registration of these components. These base classes are used heavily within WcfEx to simplify its extension classes. In most cases, the user can simply implement either the sync or async side of an interface and rely on the base class's implementation of the other.

###APM Utilities### Implementing the IAsyncResult interface is a straightforward, but tedious thing to do. However, implementing it correctly and efficiently in a concurrent environment with exceptions is devilishly tricky.

The WcfEx SyncResult and AsyncResult classes provide a concurrent and exception-correct implementation of IAsyncResult for synchronous and asynchronous operations, respectively. These classes also lazily allocate the AsyncWaitHandle property, avoiding an expensive event handle allocation when it is not used.

For synchronous operations:

public String Trim (String str)
{
   return str.Trim();
}
public IAsyncResult BeginTrim (String str, AsyncCallback callback, Object state)
{
   var trimmed = Trim(str);
   return new SyncResult(callback, state, trimmed);
}
public String EndTrim (IAsyncResult result)
{
   return ((SyncResult)result).GetResult<String>();
}

For asynchronous operations:

public String Trim (String str, TimeSpan timeout)
{
   return EndTrim(BeginTrim(str, timeout, null, null));
}
public IAsyncResult BeginTrim (String str, TimeSpan timeout, AsyncCallback callback, Object state)
{
   var result = new AsyncResult(callback, state, timeout);
   ThreadPool.QueueUserWorkItem(o => result.Complete(str.Trim()), null);
   return result;
}
public String EndTrim (IAsyncResult result)
{
   return ((AsyncResult)result).GetResult<String>();
}