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Lesson 4: Beginning the Conversation

In this lesson, you will learn to start a conversation that spans two instances of the Database Engine and send a request message from the initiator instance to the target instance. Run these steps from a copy of Management Studio running on the same computer as the initiator instance.

Procedures

Switch to the InitiatorDB database

  • Copy and paste the following code into a Query Editor window. Then, run it to switch context to the InstInitiatorDB database where you will initiate the conversation.

    USE InstInitiatorDB;
GO

Start a conversation and send a request message

  • Copy and paste the following code into a Query Editor window. Then, run it to begin a conversation and send a request message to the //TgtDB/2InstSample/TargetService in the InstTargetDB. The code must be run in one block because a variable is used to pass a dialog handle from BEGIN DIALOG to the SEND statement. The batch runs the BEGIN DIALOG statement to begin the conversation, and then builds a request message. Then, it uses the dialog handle in a SEND statement to send the request message on that conversation. The last SELECT statement just displays the text of the message that was sent.

    DECLARE @InitDlgHandle UNIQUEIDENTIFIER;
DECLARE @RequestMsg NVARCHAR(100);

BEGIN TRANSACTION;

BEGIN DIALOG @InitDlgHandle
     FROM SERVICE [//InstDB/2InstSample/InitiatorService]
     TO SERVICE N'//TgtDB/2InstSample/TargetService'
     ON CONTRACT [//BothDB/2InstSample/SimpleContract]
     WITH
         ENCRYPTION = ON;

SELECT @RequestMsg = N'<RequestMsg>Message for Target service.</RequestMsg>';

SEND ON CONVERSATION @InitDlgHandle
     MESSAGE TYPE [//BothDB/2InstSample/RequestMessage]
     (@RequestMsg);

SELECT @RequestMsg AS SentRequestMsg;

COMMIT TRANSACTION;
GO

Next Steps

You have successfully started a conversation and sent the request message to the target service. Next, you will receive the request message from the target queue and send a reply message to the initiator service. See Lesson 5: Receiving a Request and Sending a Reply.