How to delay queue processing?

I am looking for some suggestions on how to implement a delay in processing
queue elements. For example, I am using a queue to process requests to call
a web service. If the web service is unable to process a particular request,
I would like that request to be retried 5 minutes from now while continuing
to process other requests that may be in the queue. I suspect I may need
additional queues, such as a delay queue. Any ideas would be appreciated.

TIA -- Keith.Conversation Timers can be used to do something periodically or to do something after a fixed delay. You can either keep the same dialog you received the message came in on, set a timer and then send the message again when the timer message is received or else put the messages on a different queue and then process that queue periodically. The first option will require keeping the message body around somewhere - either by using retension on the queue or by keeping it in a seperate table (maybe indexed by dialogID).

Here's a little sample that uses timere to do something once a minute:

-- Set up a queue for the timer sample

CREATE QUEUE [TimerQueue]

CREATE SERVICE [TimerService] ON QUEUE [TimerQueue]([DEFAULT]) ;

CREATE SERVICE [TimerResponseService] ON QUEUE [TimerQueue];

GO

-- Create the stored procedure to handle the timer messages

CREATE PROCEDURE [dbo].[HandleTimer] AS

DECLARE @.conversationHandle uniqueidentifier

DECLARE @.message_type_name sysname

DECLARE @.dialog uniqueidentifier

BEGIN TRANSACTION

-- Timer messages only happen once a minute so there's no

-- need to receive in a loop.

WAITFOR (

RECEIVE top(1)

@.message_type_name=message_type_name,

@.dialog = conversation_handle

FROM [TimerQueue]

), TIMEOUT 500

IF (@.message_type_name = 'http://schemas.microsoft.com/SQL/ServiceBroker/DialogTimer')

BEGIN

-- Start the next cycle

BEGIN CONVERSATION TIMER ( @.dialog ) TIMEOUT = 60;

-- Do Whatever you want to do here

END

COMMIT TRANSACTION

go

ALTER QUEUE [TimerQueue] WITH ACTIVATION (

STATUS = ON, PROCEDURE_NAME = HandleTimer ,

MAX_QUEUE_READERS = 1,EXECUTE AS SELF)

go

DECLARE @.conversationHandle uniqueidentifier

BEGIN DIALOG CONVERSATION @.conversationHandle

FROM SERVICE [TimerResponseService]

TO SERVICE 'TimerService';

BEGIN CONVERSATION TIMER ( @.ConversationHandle ) TIMEOUT = 60;