The Package Backout utility enables you to back up and recover non-editable types, using a backup group controlled within SCLM. The backout process restores an executable environment by promoting the previously backed up modules from the backup group. Source members are recoverable through versioning, using SCLM services and administration procedures external to the Package Backout processes.

The term "package" refers to an SCLM architecture member that is used during the build and promote processes within SCLM. This architecture member defines the modules/ARCHDEF members that are promoted using include or change code parameters.

The libraries that contain packages are determined by using the ISAPACK=Y flag on the FLMTYPE macro within the project definition. If an architecture member is promoted from a library which does not have an ISAPACK=Y flag then the package backout process will not be invoked and no modules will be backed up.

To recover source or editable types, you must implement versioning at the group being targeted for package backout.

During package backout, the Copy phase of the promote process is triggered, to allow DB2® BINDs to be performed against any recovered DBRMs, and the Purge phase is triggered to delete the backed-up modules. Promote copy and purge exit processing is also invoked during the package backout process. This ensures the integrity of backed out load modules and ensures that any other exit processing that is in place during a normal copy or purge promote process is maintained.

Package Backout involves two phases: Backup and Restore.

The backup phase occurs during a Promote process (see Figure 1). For each member of a package marked for backout, it:

1. Copies the old members to the existing backup data set.
2. Saves the package details into the Package Details file.
3. Allows the promote to continue.

The restore phase occurs when requested by the user (see Figure 1). Restore promotes the old members back to the original group.

Package backout enables users to quickly restore an executable environment. The backout process restores the previously backed up package modules through the promote process from the backup group.

Once the immediate problem has been resolved in the executable environment, the user must apply the changes to the source using the normal development process. Use version retrieval to retrieve the version of the source corresponding to the backed out member into a development group for editing, or make the change in the existing copy of the member in the hierarchy.

The Package Details file holds the date and time details of both the backed up members and the editable members in the package, so these can be used as input to determine the appropriate versions to be recovered.

A package has the status of "BACKEDUP" when it is initially backed up, and "RESTORED" after a package-level restore is performed.

A similar status is retained against the backed-up member, showing either "BACKEDUP", or "RESTORED" if it is restored using a member-level restore.

To be able to recover source parts using Package Backout, versioning must be implemented for any editable types (such as source) that are promoted to a level at which Package Backout has been implemented.