Add assembly references

Add references to the following assemblies in your existing web project:

• System.ServiceModel
• System.ServiceModel.Activation
• System.ServiceModel.Web

Create service class

Create a new service class where you will implement the service:

[ServiceContract]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
public class LetterService
{
    [WebGet(UriTemplate = "")]
    public List<string> GetList()
    {
        return new List<string>{"a", "b", "c"};
    }
}

Register service route

In Global.asax.cs, define a route to the service:

void Application_Start(object sender, EventArgs e)
{
    RouteTable.Routes.Add(new ServiceRoute("letter", new WebServiceHostFactory(), typeof(LetterService)));
}

Enable ASP.NET compatability

Add the following to web.config:

<configuration>
   <system.serviceModel>
      <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>
   </system.serviceModel>
</configuration>

…and you are good to go! The service will be available on http://<server>/letter

Optional: enable help

In order to get a nice help page for clients connecting to the service, add the following under the system.serviceModel element in web.config:

<standardEndpoints>
   <webHttpEndpoint>
      <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true" />
   </webHttpEndpoint>
</standardEndpoints>

Then, help will be available on http://<server>/letter/help