Enabling WCF in IIS 7 on Vista

I created a Silverlight-enabled WCF service which worked perfectly when running my Silverlight app from Visual Studio, but as soon as I deployed to IIS 7 on my machine and opened it outside of VS I received the following error:

Unhandled Error in Silverlight 2 Application Exception has been thrown by the target of an invocation. at System.RuntimeMethodHandle._InvokeMethodFast
…… (there was more

I couldn’t be sure whether this was a Silverlight or a WCF issue so I opened the SVC url in my browser and received a (405) Method Not Allowed response. I checked IIS and discovered there was no HTTP Handler set up for WCF services.

I then managed to find this very helpful post about setting up WCF HTTP Handlers in IIS 7, and the solution described worked perfectly for me. Here are the steps:

1. Open a command prompt as administrator
2. CD to c:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation
3. Type ServiceModelReg -i and press return
4. A whole load of lines like “Installing: HTTP Handlers” will print out to the console. When it’s finished go into IIS 7 and open the HTTP Handlers list for your website. You should see a couple of new ones for the *.svc extension

Also, another issue I came across while trying to track down how to set these up was where people were deploying their WCF/Silverlight project to IIS 7 without updating their web.config to change the server binding reference. When you add a service reference to your Silverlight project the url is stored in the ServiceReferences.ClientConfig file, but if the WCF project is defined in the same solution then the URL will point to the local Cassini server, which means the service call will fail when you deploy the app to IIS.

One solution to the issue is to override the service URL in code, so that you don’t have to keep updating the .config file when you deploy to a web server.