Activity correlation：活动关联，确保两个活动一起工作。
当使用多个活动来完成单个操作时需要使用Activity correlation，WF4中的Send和ReceiveReply活动就是很好的例子。当我们使用ReceiveAndSendReply 或 SendAndReceiveReply 模板时，需要的活动的关联都已经自动的配置好了，但是如果我们在代码中使用Send 和 ReceiveReply或者 Receive 和SendReply活动时，就需要自己手动去实现，如没有改关联会有下面异常：System.InvalidOperationException：
The Send activity is configured with a request/reply Operation 'GetData', however, there is no ReceiveReply activity paired with it. Please pair Send with ReceiveReply and correlate them using a CorrelationHandle.
有不同的方式来配置活动关联，第一种就是使用CorrelationScope活动，CorrelationScope会自动的创建所需要的关联句柄，并且消息活动将会使用这个句柄。
下面是例子：
static Activity CreateWorkflow()
{
var getDataResult = new Variable<string>();
var handel = new Variable<CorrelationHandle>();
var send = new Send()
{
CorrelationInitializers =
{
new RequestReplyCorrelationInitializer()
{
CorrelationHandle = handel
}
},
OperationName = "GetData",
ServiceContractName = "IService1",
Endpoint = new Endpoint()
{
Binding = new BasicHttpBinding(),
AddressUri = new Uri("http://localhost:8080/GetDataService/")
},
Content = new SendParametersContent()
{
Parameters =
{
{"value", new InArgument<int>(42)}
}
}
};
var receive = new ReceiveReply()
{
Request = send,
Content = new ReceiveParametersContent
{
Parameters =
{
{"GetDataResult", new OutArgument<string>(getDataResult)}
}
}
};
var workflow = new Sequence()
{
Variables = { getDataResult, handel },
Activities =
{
send,
receive,
new WriteLine() { Text = getDataResult }
}
};
return workflow;
}
上面我们是使用RequestReplyCorrelationInitializer，我们还可以使用CorrelationScope来完成同样的事情，创建同样的工作流，如下：
static Activity CreateWorkflow()
{
var getDataResult = new Variable<string>();
var send = new Send()
{
OperationName = "GetData",
ServiceContractName = "IService1",
Endpoint = new Endpoint()
{
Binding = new BasicHttpBinding(),
AddressUri = new Uri("http://localhost:8080/GetDataService/")
},
Content = new SendParametersContent()
{
Parameters =
{
{"value", new InArgument<int>(42)}
}
}
};
var receive = new ReceiveReply()
{
Request = send,
Content = new ReceiveParametersContent
{
Parameters =
{
{"GetDataResult", new OutArgument<string>(getDataResult)}
}
}
};
var workflow = new Sequence()
{
Variables = { getDataResult },
Activities =
{
new CorrelationScope()
{
Body = new Sequence()
{
Activities = { send, receive }
}
},
new WriteLine() { Text = getDataResult } }
};
return workflow;
}本文转自生鱼片博客园博客，原文链接：http://www.cnblogs.com/carysun/archive/2009/12/06/wf4-Activitycorrelation.html，如需转载请自行联系原作者
