I am developing a Windows service that exposes a WCF service intended to be consumed by a Silverlight application, as explained in this blog post: http://mtaulty.com/Communi
Please look at the following folder for System.ServiceModel.Web.dll
C:\Program Files\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\
Are you targetting .NET4 Full or Client Profile? The latter does not include the System.ServiceModel.Web assembly.
I use Visual Web Developer and facing the same issue. My project is already configured targetting .Net 4.0 Framework. The solution for my case is adding reference to my my project by :
right click on References, choose Add Reference and find System.ServiceModel.Web under .Net Tab
Add the following reference to your project
System.ServiceModel.Web.dll
If you are not able to find System.ServiceModel.Web in - 'Add Reference' click on Component Name to sort the list.
Check your project properties and on the Application tab make sure you have selected the full ".NET FRAMEWORK" and not ".NET FRAMEWORK CLIENT PROFILE" in the target framework combo.
Apparently when you select .NET framework 4.0 while creating the project, Visual Studio 2010 Beta 2 actually targets .NET framework 4 client profile. Change the target framework to .NET framework 4 using project properties.