using System.ServiceModel;

namespace IBLL
{
    /// <summary>
    /// 服务契约接口
    /// </summary>
    [ServiceContract]
    public interface IWcfDemoService
    {
        /// <summary>
        /// 一个操作契约 (等同于WebService中的WebMethod)
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        [OperationContract]
        int Add(int a, int b);
    }
}

using IBLL;

namespace BLL
{
    /// <summary>
    /// 实现服务契约业务类
    /// </summary>
    public class WcfDemoService: IWcfDemoService
    {
        public int Add(int a, int b)
        {
            return a + b;
        }
    }
}

<%@ ServiceHost Service="BLL.WcfDemoService" %>

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.5"/>
    <httpRuntime targetFramework="4.5"/>
    <customErrors mode="Off"/>
  </system.web>

  
  <!-- WCF 配置开始 -->
  <system.serviceModel>

    <services>
      <!-- 注意: 服务名称必须与服务实现的配置名称相匹配。 -->
      <service name="BLL.WcfDemoService" behaviorConfiguration="BLL.WcfDemoService" >
        <!-- 添加下列终结点。 -->
        <!-- 注意: 服务必须有一个 http 基址以便添加此终结点。 -->
        <endpoint contract="IBLL.IWcfDemoService" binding="mexHttpBinding" address="mex" />
      </service>
    </services>

    <behaviors>
      <serviceBehaviors>
        <behavior name="BLL.WcfDemoService" >
          <!-- 将下列元素添加到服务行为配置中。 -->
          <serviceMetadata httpGetEnabled="true" />
        </behavior>
      </serviceBehaviors>
    </behaviors>

  </system.serviceModel>
  <!-- WCF 配置结束 -->
  

</configuration>