How to handle EndDialog message when using Asynchronous Trigger Pattern?

Question

I have Service A which sends a message to Service B when a update/delete/insert trigger fires.  Service B dequeing logic looks like:
declare @messagebody xml
declare @messagetype nvarchar(256)
declare @cg uniqueidentifier
declare @ch uniqueidentifier
DECLARE @messages TABLE(messagetype nvarchar(256),messagebody xml)
begin try
begin transaction;
waitfor
receive top (1)
@cg = conversation_group_id,
@ch = conversation_handle,
@messagetype = message_type_name,
@messagebody = cast(message_body as xml)
from MyPolicyQueue
),TIMEOUT @receiveTimeoutMs
if @messagebody is not null
begin
insert into @messages values (@messagetype, @messagebody)
end
select * from @messages
end conversation @ch
commit
end try
ServiceB will end the conversation but afterwards, the queue now has an EndDialog message that never gets processed.
The intent is asynchronous handling of update messages with the trigger used as the event source.  Service B closes the conversation but trigger does not (It would probably be a very bad thing if trigger blocked waiting for EndDialog message response).
  How do you handle the EndDialog message in this scenario?
The code is based on this example.
scott

Answer 1

A common practice is to create an activated proc on the initiator queue to close the conversation loop after the target service does it's job.  This activated proc simply ends the conversation upon receipt of an EndDialog message type.  If
an unexpected message type is received (including Error), the proc can end the conversation with error and perhaps log the details to a table that can be monitored for exceptions.
See Rusanu's artice for a description of this pattern:
http://rusanu.com/2006/04/06/fire-and-forget-good-for-the-military-but-not-for-service-broker-conversations/
Dan Guzman, SQL Server MVP, http://www.dbdelta.com