Silverlight与自托管WCF使用TCP双工通信

“跨域访问”问题

异常信息

未能连接到 net.tcp://localhost:4503/IMyService。连接尝试的持续时间为 00:00:00.3300189。TCP 错误代码 10013: 试图以其访问权限所禁止的方式访问套接字。。原因可能是，试图以跨域的方式访问某服务，而该服务的配置不支持跨域访问。您可能需要与服务的所有者联系，以公开通过 HTTP 的套接字跨域策略，并在允许的套接字端口范围 4502-4534 之内承载该服务。

解决

让客户端能以“http://<<YourNetTcpIPAddress>>:80/clientaccesspolicy.xml”方式访问到跨域访问配置。

跨域配置内容

<?xml version="1.0" encoding="utf-8"?>
<access-policy>
  <cross-domain-access>
    <policy>
      <allow-from http-request-headers="*">
        <domain uri="*" />
      </allow-from>
      <grant-to>
        <socket-resource port="4502-4534" protocol="tcp" />
      </grant-to>
    </policy>
  </cross-domain-access>
</access-policy>

解决方案

ClientCrossDomainAccessPolicy类

using System;
using System.IO;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.ServiceModel.Web;
using System.Text;

public static class ClientCrossDomainAccessPolicy
{
    [ServiceContract]
    public interface IPolicy
    {
        //确定可以访问“http://localhost:80/clientaccesspolicy.xml"
        [OperationContract, WebGet(UriTemplate = "/clientaccesspolicy.xml")]
        Stream GetSilverlightPolicy();

        //确定可以访问“http://localhost:80/crossdomain.xml"
        [OperationContract, WebGet(UriTemplate = "/crossdomain.xml")]
        Stream GetFlashPolicy();
    }

    class Policy : IPolicy
    {
        #region IClientAccessPolicy Members

        Stream StringToStream(string result)
        {
            var oc = WebOperationContext.Current;
            if (oc == null)
                throw new NullReferenceException("WebOperationContext");

            oc.OutgoingResponse.ContentType = "application/xml";
            return new MemoryStream(Encoding.UTF8.GetBytes(result));
        }
        public Stream GetSilverlightPolicy()
        {
            const string result = @"<?xml version=""1.0"" encoding=""utf-8""?>
<access-policy>
    <cross-domain-access>
        <policy>
            <allow-from http-request-headers=""*"">
                <domain uri=""*""/>
            </allow-from>
            <grant-to>
                <socket-resource port=""4502-4534"" protocol=""tcp"" />
            </grant-to>
        </policy>
    </cross-domain-access>
</access-policy>";
            return StringToStream(result);
        }

        public Stream GetFlashPolicy()
        {
            const string result = @"<?xml version=""1.0""?>
<!DOCTYPE cross-domain-policy SYSTEM ""http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd"">
<cross-domain-policy>
    <allow-access-from domain=""*"" />
</cross-domain-policy>";
            return StringToStream(result);
        }

        #endregion
    }

    public static ServiceHost GetHost()
    {
        var policyHost = new ServiceHost(typeof(Policy), new Uri("http://localhost:80"));//端口必须为80。若非TCP，像如HTTP托管，则直接将Policy发布至根下即可
        policyHost.AddServiceEndpoint(typeof(IPolicy), new WebHttpBinding(), string.Empty).Behaviors.Add(new WebHttpBehavior());

        return policyHost;
    }
}

使用方式

            /////////////////////////////////////////////////
            //加上以下三行以解决Silverlight跨域访问问题。实现效果：可以直接访问“http://localhost:80/clientaccesspolicy.xml"与“http://localhost:80/crossdomain.xml"读取跨域授权配置文件
            using (var policyHost = ClientCrossDomainAccessPolicy.GetHost())
            {
                policyHost.Open();

//写你自己的代码...

效果截图

参考

Policy file for NetTcp

Using Silverlight 4 and Net.TCP Duplex Callbacks

示例代码下载