Lesson 3: Begin a conversation and transmit messages

Applies to: SQL Server Azure SQL Managed Instance

In this lesson, you learn to complete a basic request-reply message cycle in a system configured with an internal activation stored procedure.

Procedures

Switch to the AdventureWorks database

Copy and paste the following code into a Query Editor window, then run it to switch context to the AdventureWorks2025 database.

USE AdventureWorks2022;
GO

Begin a conversation and send a request message

Copy and paste the following code into a Query Editor window, then run it to start a conversation and send a request message to the //AWDB/InternalAct/TargetService. 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 start the conversation. It builds a request message, then uses the dialog handle in a SEND statement to send the request message on that conversation. The last SELECT statement displays the text of the message that was sent.

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

BEGIN TRANSACTION;

BEGIN DIALOG @InitDlgHandle
    FROM SERVICE [//AWDB/InternalAct/InitiatorService]
    TO SERVICE N'//AWDB/InternalAct/TargetService'
    ON CONTRACT [//AWDB/InternalAct/SampleContract]
    WITH ENCRYPTION = OFF;

-- Send a message on the conversation
SELECT @RequestMsg = N'<RequestMsg>Message for Target service.</RequestMsg>';

SEND ON CONVERSATION (@InitDlgHandle)
    MESSAGE TYPE [//AWDB/InternalAct/RequestMessage] (@RequestMsg);

-- Display sent request.
SELECT @RequestMsg AS SentRequestMsg;

COMMIT TRANSACTION;
GO

Receive the request and send a reply

When you send the request message, Service Broker automatically activates a copy of TargetActiveProc. The stored procedure receives the reply message from the TargetQueueIntAct and sends a reply message back to the initiator.

Receive the reply and end the conversation

Copy and paste the following code into a Query Editor window. Then, run it to receive the reply message and end the conversation. The RECEIVE statement retrieves the reply message from the InitiatorQueueIntAct. The END CONVERSATION statement ends the initiator side of the conversation and sends an EndDialog message to the target service. The last SELECT statement displays the text of the reply message so that you can confirm it's the same as what was sent in the previous step.

DECLARE @RecvReplyMsg AS NVARCHAR (100);
DECLARE @RecvReplyDlgHandle AS UNIQUEIDENTIFIER;

BEGIN TRANSACTION;

WAITFOR (RECEIVE TOP (1) @RecvReplyDlgHandle = conversation_handle,
    @RecvReplyMsg = message_body FROM InitiatorQueueIntAct),
TIMEOUT 5000;

END CONVERSATION @RecvReplyDlgHandle;

-- Display received request.
SELECT @RecvReplyMsg AS ReceivedReplyMsg;

COMMIT TRANSACTION;
GO

End the target side of the conversation

When you run the END CONVERSATION statement for the initiator, Service Broker sends an EndDialog message to the TargetQueueIntAct queue. The TargetActiveProc procedure receives the EndDialog message and issues an END CONVERSATION that ends the target side of the conversation.

Next step

You successfully completed a request-reply message cycle between the //AWDB/InternalAct/InitiatorService and the //AWDB/InternalAct/TargetService. You can repeat the steps in this lesson as many times as you want to transmit a request-reply pair of messages. When you finish investigating the SEND and REPLY statements, you can drop all the objects that were used by the conversation.