WCF REST on Sharepoint

SampleService.csproj

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <!-- .... -->
	  
	  <!-- 
	      Add .svc to let build tool to substitute$SharePoint.Project.AssemblyFullName$ like
	      placeholders during build process.
	      
	      use ; to separate multiple:   svc;ashx;...
	  -->
	  <TokenReplacementFileExtensions>svc</TokenReplacementFileExtensions>
  
  </PropertyGroup>
  <!-- .... -->
</Project>

SampleService.svc

<%@ServiceHost
     language= "C#"
     Service="MyNamespace.TestService, $SharePoint.Project.AssemblyFullName$"
     Factory= "Microsoft.SharePoint.Client.Services.MultipleBaseAddressWebServiceHostFactory, 
    Microsoft.SharePoint.Client.ServerRuntime, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c"%>

<!-- 
  Microsoft.SharePoint.Client.Services.MultipleBaseAddressWebServiceHostFactory  for REST
  Microsoft.SharePoint.Client.Services.MultipleBaseAddressBasicHttpBindingServiceHostFactory  for SOAP


http://host/sitecollurl/_layouts/15/solution_name/SampleService.svc/Do
http://host/sitecollurl/_layouts/15/solution_name/SampleService.svc/DoWork/12
-->

TestService.cs

namespace MyNamespace
{
    [ServiceContract]
    public interface ITestService
    {
        [OperationContract]
        [WebInvoke(Method = "GET",ResponseFormat = WebMessageFormat.Json,BodyStyle = WebMessageBodyStyle.Bare)]
        string Do();


        [OperationContract]
        [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json,UriTemplate = "DoWork/{id}")] 
        // .../_layouts/15/solution_name/SampleService.svc/DoWork/12
        string DoWorkWithParams(int id);
    }

    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
    public class TestService : ITestService
    {
        public string Do()
        {
            return "OK";
        }

        public string DoWorkWithParams(int id)
        {
            return "Do: " + id;
        }
    }
}