If InterChange Server Express fails when processing events, all the events currently in the Work-in-Progress (WIP) queue must be either recovered or otherwise processed when the server reboots. Potentially, because of memory requirements, the recovery of the WIP events can slow or even halt the server reboot. The InterChange Server Express product provides two features--deferred recovery and asnynchronous recovery--for improving the time it takes the server to reboot and for making the server available for other work before all events have been recovered.
Flow control and storing business object keys as part of the WIP data assist in the efficiency of deferred recovery and asynchronous recovery. Both features reduce the amount of memory needed during an InterChange Server Express recovery, and therefore, can decrease significantly the amount of time necessary for InterChange Server Express to reboot during a recovery.
Storing business object keys as part of the WIP data means that during recovery, the business object key is retrieved without deserializing the business object, avoiding an MQ or a database round-trip. Flow control is a service that allows you to configure either system-wide or component-level queue depth parameters in to control the memory demands on InterChange Server Express. For more information about configuring flow control, see Steps for configuring system-wide flow control.
In deferred recovery, recovery of a collaboration's WIP events is deferred until after the server has rebooted, thereby saving the memory usage associated with those events.
After the server has rebooted, you can resubmit the events manually. Note the following recommendations:
You establish deferred recovery by setting the RECOVERY_MODE property of a collaboration object.
The RECOVERY_MODE property has two settings, which do the following when a server failure and reboot occurs:
Events that were in the Working state before the server failure are changed to the Deferred state. No events for this collaboration are recovered until you resubmit them manually.
Events that were in the Working state before the server failure are recovered. Events in the Deferred state remain deferred until you resubmit them.
The default setting is Always.
Figure 60. Properties dialog box, Collaboration General Properties tab
The collaboration recovers all WIP events whose state is Working and that it owns at the time of server boot.
The collaboration changes the WIP event to the Deferred recovery state. You must process those events at a later time using the Flow Manager or Failed Event Manager. For more information, see Working with failed events.
InterChange Server Express does not wait for collaborations and connectors to recover before it completes the boot process; collaborations and connectors are allowed to recover asynchronously after InterChange Server Express has booted. This makes it possible to use troubleshooting tools -- such as System Monitor, Failed Event Manager, and Flow Manager -- when the connectors and collaborations are recovering.