c# - 双工 channel 故障事件不会在第二次连接尝试时出现

Question

我有常规的 net.tcp WCF 服务客户端和常规的 net.tcp duplex(即带有回调)WCF 服务客户端。我已经实现了一些逻辑，以在服务出现故障时不断地重新实例化连接。

它们的创建方式完全相同:

FooServiceClient Create()
{
    var client = new FooServiceClient(ChannelBinding);
    client.Faulted += this.FaultedHandler;
    client.Ping(); // An empty service function to make sure connection is OK
    return client;
}

BarServiceClient Create()
{
    var duplexClient = new BarServiceClient(new InstanceContext(this.barServiceCallback));
    duplexClient.Faulted += this.FaultedHandler;
    duplexClient.Ping(); // An empty service function to make sure connection is OK
    return duplexClient;
}

public class Watcher
{
public Watcher()
{
    this.CommunicationObject = this.Create();
}

ICommunicationObject CommunicationObject { get; private set; }

void FaultedHandler(object sender, EventArgs ea)
{
    this.CommunicationObject.Abort();
    this.CommunicationObject.Faulted -= this.FaultedHandler;
    this.CommunicationObject = this.Create();
}
}

FaultedHandler() 中止 channel 并使用上面的代码重新创建它。

FooServiceClient 重新连接逻辑工作得很好，它在多次故障后正在重新连接。然而，几乎相同但双工的 BarServiceClient 仅从第一个 BarServiceClient 实例接收 Faulted 事件，即 一次。

为什么只有双工 BarServiceClient 的第一个实例得到错误事件？有任何解决方法吗？

---

类似的未回答问题:WCF Reliable session without transport security will not faulted event on time

Answer 1

经过两天与 WCF 的斗争后，我找到了解决方法。

有时 WCF 会触发 Faulted 事件，但有时不会。但是，Closed 事件始终会被触发，尤其是在 Abort() 调用之后。

所以我在 FaultedHandler 中调用了 Abort()，它有效地触发了 Closed 事件。随后，ClosedHandler 执行重新连接。如果 Faulted 从未被框架触发，则始终会触发 Closed 事件。

BarServiceClient Create()
{
    var duplexClient = new BarServiceClient(new InstanceContext(this.barServiceCallback));
    duplexClient.Faulted += this.FaultedHandler;
    duplexClient.Closed += this.ClosedHandler;
    duplexClient.Ping(); // An empty service function to make sure connection is OK
    return duplexClient;
}

public class Watcher
{
public Watcher()
{
    this.CommunicationObject = this.Create();
}

ICommunicationObject CommunicationObject { get; private set; }

void FaultedHandler(object sender, EventArgs ea)
{
    this.CommunicationObject.Abort();
}

void ClosedHandler(object sender, EventArgs ea)
{
    this.CommunicationObject.Faulted -= this.FaultedHandler;
    this.CommunicationObject.Closed -= this.ClosedHandler;
    this.CommunicationObject = this.Create();
}
}