Phase Freeze Concept
Long-running projects face the challenge that either the process instance used throughout the project lifetime is getting outdated or at best does not benefit from process improvements, or the process instance gets updated on a regular basis but might demand additional tasks to be executed for process parts that were already completed in the past.
A process is typically divided into phases that have a defined completion gate and time (typically a milestone) and have a chronological order. Therefore those phases are a suitable entity to distinguish process parts that are already completed and need to be stable from process parts that are still executed and therefore should get updated.
Note: While this guide uses the terminology of freezing phases Stages is not restricted to using phases as freezable elements but almost any kind of element.
Stages processes are distributed and updated by utilizing the concept of core processes. For preventing process modifications, Stages provides the concept of process baselines. There is a working revision of a process which is updateable and optionally further saved baselines of a process that cannot be modified. One of those process baselines is declared as valid version and used for process execution. With these existing concepts a process can only be updated or frozen as a whole.
To achieve the goal of freezing process parts, the concept of process phases or as general term process modules is needed. A process module is defined by its root element and rules of which dependent and associated elements are also part of the module (e.g. a phase and all its executed activities).
Executing the Phase Freeze for a certain phase will create a new process baseline based on the valid version to save the state of the process at the time of freezing. From those frozen baselines and the working revision, a new merged valid version is created that contains the state of the frozen baselines for elements of frozen phases and the updated working revision for not frozen elements.
There might be process elements that are used in more than one phase, so they might be needed in an older revision for a frozen phase while other unfrozen phases need the up to date revision. These kinds of conflicts are resolved by moving the older frozen revision of shared elements below a new process element folder called “Duplicates for phase XXX”.
Project data like project attributes and files are no longer editable in case the owning process element is part of a frozen phase. Therefore not only the process but also the project state of that phase is frozen.