Table of Contents for SharePoint as a WCF host. 

1. Create a WCF Home. This is the virtual directory that will host all your WCF endpoints.

2. Create a WCF Service Library, and throw it in the GAC.

3. Create a relevant .svc file in the WCF home you created in step #1.

4. Write a WCF Virtual Path Provider, and register it in the SharePoint site.

Okay good, so you created a _wcf home, and you created a service in a service library. The service library is in the GAC.

The next step is to create a .svc file.

Well, here is how my HelloWorld.svc looks like -

<%@ Assembly Name="HelloWorld, Version=1.0.0.0, Culture=neutral, PublicKeyToken=0512278251be14ea"%> 
<% @ServiceHost Service="HelloWorld.service1" %>

Well, is that enough? Not nearly. You haven't specified the endpoint details yet.

In the same _wcf home, create a web.config that looks like this -

   1:  <?xml version="1.0" encoding="utf-8"?>

   2:  <configuration>

   3:    <system.serviceModel>

   4:      <services>

   5:        <service behaviorConfiguration="HelloWorld.service1Behavior" name="HelloWorld.service1">

   6:          <endpoint address="" binding="wsHttpBinding" contract="HelloWorld.IService1" />

   7:          <host>

   8:            <baseAddresses>

   9:              <add baseAddress="http://moss2007/_wcf/" />

  10:            </baseAddresses>

  11:          </host>

  12:        </service>

  13:      </services>

  14:      <behaviors>

  15:        <serviceBehaviors>

  16:          <behavior name="HelloWorld.service1Behavior">

  17:            <serviceMetadata httpGetEnabled="true" />

  18:            <serviceDebug includeExceptionDetailInFaults="false" />

  19:          </behavior>

  20:        </serviceBehaviors>

  21:      </behaviors>

  22:    </system.serviceModel>

  23:  </configuration>

As you can see above, very very similar to hosting it in a plain vanilla IIS website, I have specified endpoint details. The important/interesting thing to note here is that the base address - is your WCF home.

Great you should be all set huh? Not nearly.

If this was plain vanilla IIS/ASP.NET, then you would have been all set. But go ahead and try accessing your .svc file at http://moss2007/_wcf/HelloWorld.svc and you will be greeted by the below:

What is going on??

Well, after having banged my head with reflector for a few hours, I figured out that the SPVirtualPathProvider isn't coded to handle URLs that start with '~'. (Seriously!).

Anyway, luckily ASP.NET is extensible, so I'm gonna write my own Virtual Path Provider to fix this issue.