The EchoService has a very simple ServiceContract, which contains a single Echo operation to return some data of type String (refer to the following code snippet).

[ServiceContract]
public interface IEchoService
{
    [OperationContract]
    string Echo();
}

To enable ASP.NET Compatibility Mode, we can simply set the aspNetCompatibilityEnabled attribute to true in the <serviceHostingEnvironment> setting of the WCF configuration section. The following screenshot shows the configuration fragment with ASP.NET Compatibility Mode enabled.

On the service implementation class of the WCF service, we need to apply the System.ServiceModel.Activation.AspNetCompatibilityRequirements attribute and set the RequirementsMode property to AspNetCompatibilityRequirementsMode.Allowed. This is quite useful, since sometimes we might not want certain WCF services to gain access to those ASP.NET runtime context objects, even if the hosting web application has ASP.NET Compatibility Mode enabled. The following code snippet shows the implementation class of the sample EchoService, which has applied the proper AspNetCompatibilityRequirements setting:

using System.ServiceModel.Activation;

[AspNetCompatibilityRequirements(
    RequirementsMode=AspNetCompatibilityRequirementsMode.Allowed
    )]
public class EchoService : IEchoService
{
…
}

public class EchoService : IEchoService
{
   public string Echo()
   {
    var approot = HttpContext.Current.Server.MapPath("~/");

    var data = HttpContext.Current.Cache["key1"];

    var url = HttpContext.Current.Request.RawUrl;
        
    return string.Format("{0}, {1}, {2}", approot, data, url) ;
   }
}

By performing a quick test on the WCF service in the WCF Test Client tool, we can get the expected response with all the ASP.NET context properties returned, as shown in the following screenshot: