Expressing interest in a UR

When an application program requests access to a resource, the resource manager that owns the resource needs to express an interest in the UR. The expressed interest tells RRS that the resource manager is involved with the UR. The interest can be protected, which means the changes require coordination, or unprotected, which means the changes do not require coordination.

In response, RRS invokes the resource manager's exit routines in the syncpoint processing of the UR, enabling the resource manager to protect its resource.

Most database accesses are read-only accesses. For a read-only access, the resource manager should express an unprotected interest in the UR. The resource manager's exit routines are invoked; however, if a failure occurs, RRS does not needlessly inform the resource manager that it previously expressed interest in the UR.

If your resource manager expects to process multiple URs for the same work context, see Using context services.

The services related to expressing interest in a UR are:

Callable service	Description
Express_UR_Interest	Express® an interest in a UR and provide persistent and nonpersistent interest data.
Retrieve_Interest_Count	Determine if resource managers have expressed more than one interest in a UR.
Change_Interest_Type	Change the interest type from unprotected to protected.
Retain_UR_Interest	Express interest in the next UR for the current context.
Delete_UR_Interest	Delete an interest in a UR.

For more information, see Callable resource recovery services.

On Express_UR_Interest, you specify the type of two-phase commit protocol for the UR, and there are additional techniques you can use to optimize RRS processing.