Hi John, The Cron expression in MP is used to create firing schedules such as "At 8:00am every Monday through Friday" [1]. If it is set the MP will run according to that. Otherwise MP will poll the queue with the specified interval value continuously.
Also the MP has a parameter called max_delivery_attempts (defaults to 4), which defines the maximum retry attempts in case of a failure in end point. By default if the MP could not send the message to the end point after this number of retry count, it deactivates itself. But that message remains in the queue. After that you have to activate the MP explicitly to make the next schedule to be effective. Otherwise it will remain deactivated. If you need to override the above behaviour, you need to enable max-delivery-drop parameter, so that if the MP could not send the message after this number of attempts, it merely drops the message and continues. Here you loose the message if the endpoint is down. [1] http://www.quartz-scheduler.org/documentation/quartz-1.x/tutorials/crontrigger Thanks & Regards, On Thu, Sep 3, 2015 at 8:05 PM, John Hawkins <[email protected]> wrote: > Hi All, > > I'm trying to figure out when does the "cron schedule" get used that I > can configure on the MessageProcessor? > > The logic that I think is happening is - if the message fails to get sent > 'retry' number of times then it's put to the dead letter queue (or DLC as > its called in qpid) . The Message Processor then looks at the DLC based on > when the cron job tells it to? > > If this logic is correct (?) then I have a number of other questions > please: > > 1) what if this cron job is not set - does the message remain on the DLQ? > 2) Where is the DLQ defined to synapse/the message processor so that it > knows where to go? > 3) What if the message gets removed from the DLC for some reason (manually > or otherwise)? Do we fail quietly or log it somewhere? > 4) What if other messages from other parts of the ESB get put to the DLQ ? > How does the MessageProcessor know which messages are for it? > > > many thanks for your help ! > john. > > > John Hawkins > Director: Solutions Architecture > > > _______________________________________________ > Dev mailing list > [email protected] > http://wso2.org/cgi-bin/mailman/listinfo/dev > > -- Ravindra Ranwala Software Engineer WSO2, Inc: http://wso2.com <http://www.google.com/url?q=http%3A%2F%2Fwso2.com&sa=D&sntz=1&usg=AFQjCNEZvyc0uMD1HhBaEGCBxs6e9fBObg> Mobile: +94714198770
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