WF4:活动关联Activity correlation

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();

    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