Process choreographer: Failed message handling and quiesce mode

Process choreographer provides a facility for handling temporary infrastructure failures. This facility consists of two numerical limits, two queues, quiesce mode, and the message retry behavior.

Retry Limit

The Retry Limit defines the maximum number of times that a message can fail before being put on the hold queue. In a performance critical application running in a reliable infrastructure, the retry limit should be small, for example, one or two. This parameter can be found in the administration console, on the Business Process Container page.

Retention Queue Message Limit

The Retention Queue Message Limit defines the maximum number of messages that can be on the retention queue. If the retention queue overflows, the system goes into quiesce mode. To make the system go into quiesce mode as soon as one message fails, set the value to zero. To make the system more tolerant of infrastructure failures, increase the value. This parameter can be found in the administration console, on the Business Process Container page.

Retention Queue

The retention queue holds failed messages, that will be replayed by moving them back to the business process container's internal work queue. Any messages that have failed a number of times equal to the retry limit the message does not return to the retention queue, but instead, is moved to the hold queue. If the retention queue the retention queue is full to the limit defined by the retention queue message limit, and another message fails, the queue has overflowed, and the system goes into quiesce mode. The administrator can move the messages in this queue back to the internal queue performing the task Querying and replaying failed messages.

Hold Queue

The hold queue is where messages end up when the number of times that they have failed is equal to the retry limit. The administrator can move the messages in this queue back to the internal queue performing the task Querying and replaying failed messages.

Replay Messages

The administrator can move the messages from the hold or retention queues back to the internal queue. This is done using the Replay Messages panel for the business process container.

Quiesce Mode

Quiesce mode is entered when the retention queue overflows. When this happens, it is assumed that there is a serious, though possibly temporary, infrastructure failure. The purpose of quiesce mode is to prevent the system from using a lot of resources while an infrastructure failure means that most messages will probably fail anyway. In quiesce mode, the system sleeps for two seconds before attempting to process the next message. As soon as a message is successfully processed, the system resumes normal message processing.


Related tasks
Using scripts to query and replay failed messages



Searchable topic ID:   c7replay
Last updated: Jun 21, 2007 8:07:48 PM CDT    WebSphere Business Integration Server Foundation, Version 5.0.2
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