The resource manager, through exit routines that get control in response to events, takes actions that commit or back out changes to a resource it manages. Often an application changes more than one protected resource, so that more than one resource manager is involved. It uses a two-phase commit protocol to coordinate changes to protected resources, so that all changes are made or no changes are made. During its processing, RRS drives resource manager exit routines. A resource manager must register itself with the system as a resource manager.
Registration services is itself an exit manager, though it drives only one exit routine.
For example, when a given context ends, context services drives the end-context exit routines for each resource manager involved. To process a sync point event, a data resource manager would take actions such as committing or backing out changes to the data it manages. A communications resource manager provides access to distributed resources by allowing an application to communicate with other applications and resource managers, possibly located on different systems. It acts as an extension to the sync point manager by allowing the local sync point manager to communicate with the other sync point manager needed to ensure coordination of the distributed resources the application accesses. To process a sync point event, a communication resource manager communicates the event to the distributed sync point managers.