mex endpoint 只能以匿名方式访问。如果需要更新Silverlight 服务引用，需要同时开启IIS的匿名访问方式
1. 在web.config中开启windows authentication
<authentication mode="Windows" />
2. 配置basicHttpBinding
<system.serviceModel>
<bindings>
<basicHttpBinding>
<binding name="BasicHttpEndpointBinding">
<security mode="TransportCredentialOnly">
<transport clientCredentialType="Windows" />
</security>
</binding>
</basicHttpBinding>
</bindings>
<services>
.........
.........
</system.serviceModel>
