Access intent of a committable resource

 

The access intent determines how the resources participate together in a transaction.

When a resource is placed under commitment control, the resource manager indicates how the resource is accessed:

• Update

• Read-only

• Undetermined

The following table shows what access intents are possible for a particular type of resource and how the system determines the access intent for a resource when it is registered.

Resource type	Possible access intents	How the access intent is determined
FILE	Update, read-only	Based on how the file was opened
DDL	Update	Always update
API	Update	Always update
DDM	Update, read-only	Based on how the file was opened
LU62	Undetermined	Always undetermined
DRDA®	Update, read-only, undetermined	For DRDA Level 1, the access intent is update if no other remote resources are registered. Otherwise, the access intent is read-only. For DRDA Level 2, the access intent is always undetermined.
TCP	Undetermined	Always undetermined

The access intent of resources that are already registered determines whether a new resource can be registered. The following rules apply:

• A one-phase resource whose access intent is update cannot be registered when any of the following conditions is true:

  • Resources whose access intent is update are already registered at other locations.

  • Resources whose access intent is undetermined are already registered at other locations.

  • Resources whose access intent is undetermined are already registered at the same location and the resources have been changed during the current transaction.

• A two-phase resource whose access intent is update cannot be registered when a one-phase resource whose access intent is update is already registered.

 

Parent topic:

How commitment control works with objects