WCF - 回调到客户端（双面打印？） [英] WCF - calling back to client (duplex ?)

问题描述

我有什么样的解决方案选择问题.. 我有一个服务运行，可以从网站接收订单的服务器运行。 为了这台服务器多个客户（远程计算机）的某种联系。

I have a problem with what solution to choose.. I have a server running having a Service running that can receive orders from a website. To this server several client (remote computers) are connected somehow.

我真的想使用WCF的所有交际，但不知道这是可能的。

I would really like to use WCF for all comunication, but not sure it's possible.

我不想在配置他们的路由器的所有客户端的防火墙设置，因此客户必须连接到服务器。

I dont wanna configure all client firewall settings in their routers, so the clients would have to connect to the server.

但是，当有命令：收到所述服务器上，它应被转移到特定的客户端。

But when an order is recieved on the server, it should be transferred to a specific client.

一种解决方案可以让客户端连接使用的是双螺旋结合，但它必须以某种方式保持连接活动，以便能接收到的数据从服务器...这是一个很好的办法做到这一点？

One solution could be to have the Client connect using a duplex binding, but it will have to somehow keep the connection alive in order to be able to received data from server... Is this a good way to do this ??

通常情况下，连接超时，可能是一个很好的理由......

Normally the connection times out and probably for a good reason...

任何人有洞察力这个问题。

Anyone have insight to this problem.

THX很多的任何意见： - ）

Thx alot for any advise :-)

最好的问候 瑟伦穆勒

推荐答案

这正是双工绑定被设计为。你有两个最好的选择是 NetTcpBinding的或<一href="http://msdn.microsoft.com/en-us/library/system.servicemodel.pollingduplexhttpbinding%28VS.95%29.aspx"相对=nofollow> PollingDuplexBinding 。

This is exactly what duplex bindings were designed for. The two best choices you have are NetTcpBinding or PollingDuplexBinding.

前者使用可能不适合你的客户，如果他们不是网络上的TCP协议。然而，它确实允许经由客户端发起的插座的双向通信。因此客户端不需要能够接受输入连接。最近，我用这一个项目，它工作得很好。这也是非常敏感。当客户端应用程序关闭，服务器上的会话立即结束。

The former uses a TCP protocol which may not be suitable for your clients if they aren't on your network. However, it does allow two-way communication over a client-initiated socket. So the client doesn't need to be able to accept incoming connections. I recently used this on a project and it works very well. It's also very responsive. When client applications close, the session on the server immediately ends.

第二个选项，PollingDuplexBinding包含在Silverlight中的SDK。它采用客户端发起的长HTTP请求。请求等待需要走出去到客户端，他们到达时，客户要求退货的消息。然后客户端发起一个新的HTTP请求发送回服务器。换言之，客户机总是有一个挂起的HTTP请求。这种运作良好，在防火墙，当你在处理互联网客户端进行使用。然而，我发现这是不一样的反应NetTcpBinding的。也可能是我做错了什么，但它似乎是尝试发送回调废弃的客户端会话花了一段时间超时。

The second option, PollingDuplexBinding is included in the Silverlight SDK. It uses a client-initiated "long" HTTP request. The request waits for messages that need to go out to the client and when they arrive, the client request returns. The client then initiates a new HTTP request back to the server. In other words, the client always has a pending HTTP request. This works well over firewalls and should be used when you're dealing with internet clients. However, I've found this to be not as responsive as NetTcpBinding. I may have been doing something wrong but it seemed like attempts to send callbacks to abandoned client sessions took a while to "time out".

下面是从我最近的项目是用于NetTcpBinding的进行双工通信的配置文件的例子。需要注意的是，除了一些调整，我感到非常使用默认值，此绑定pretty的以服务节流。但是，有各种各样的东西你可以调整，如receiveTimeout，inactivityTimeout，等等。

Here's an example of the configuration file from my recent project that used NetTcpBinding for duplex communication. Note that other than some tweaks to service throttling I am pretty much using the defaults for this binding. But there's all kinds of things you can tweak such as receiveTimeout, inactivityTimeout, etc.

<configuration>
    <system.serviceModel>

        <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />

        <behaviors>
            <serviceBehaviors>
                <behavior name="">
                    <serviceMetadata httpGetEnabled="true" />
                    <serviceDebug includeExceptionDetailInFaults="true" />
                    <serviceThrottling maxConcurrentCalls="65535" 
                                       maxConcurrentSessions="65535" 
                                       maxConcurrentInstances="65535" />
                </behavior>
            </serviceBehaviors>
        </behaviors>

        <bindings>
            <netTcpBinding>
                <binding maxConnections="65535">
                    <security mode="None" />
                </binding>
            </netTcpBinding>
        </bindings>

        <services>
            <service name="BroadcastService">
                <endpoint address="" binding="netTcpBinding" contract="BroadcastService" />
            </service>
        </services>

    </system.serviceModel>
</configuration>

---

[ServiceContract( CallbackContract = typeof( IBroadcastCallback ) )]
[ServiceBehavior( ConcurrencyMode = ConcurrencyMode.Multiple )]
public class BroadcastService : IDisposable
{

    [OperationContract(IsInitiating=true)]
    public long Subscribe( Guid clientID )
    {
        // clients call this to initiate the session
    }

    [OperationContract(IsOneWay = true)]
    public void Publish( BroadcastMessage message )
    {
        // client calls this to broadcast a message to
        // all other subscribed clients via callback
    }

}

[ServiceContract( Name = "BroadcastCallback" )]
public interface IBroadcastCallback
{

    [OperationContract( IsOneWay = true, AsyncPattern = true )]
    IAsyncResult BeginBroadcast(BroadcastMessage Message, AsyncCallback callback, object state);

    void EndBroadcast( IAsyncResult asyncResult );

}   // interface

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