About Stereotype Application Repair

The EMF-based implementation of UML profiles in Papyrus has consequences for the storage of stereotype applications in Papyrus model files. Essentially, each profile applied to a model maps to an XML schema namespace which, upon loading a model, must be resolvable in the form of an EMF EPackage located either in a deployed plug-in or embedded in the UML profile, itself. Because of the dynamic nature of profiles, which can be moved from one location to another or re-defined to produce new versions over time, there are a number of ways in which stereotype applications (being effectively instances of the stereotypes defined in the profile as though they were metaclasses) can drift out of sync with the profile definition:

• the profile defining the stereotype applications may no longer be applied to the model. Normally, unapplying a profile removes all applications of its stereotypes, but this may be undone by various means: bad merges in a version control system, model units (resources) that were not available/loaded at the time, etc.
• the profile may be applied but the model may have applied a different version of the profile than the version on which the stereotype applications in the model are based. Thus the stereotype applications are properly loaded (the XML schema describing them is resolved) but they may not function correctly in the Papyrus editor
• the profile may have moved or been undeployed or is otherwise not known, resulting in the XML schema namespace in the model file being unresolved

Also, stereotype applications may sometimes become disconnected from the UML elements that they extend (effectively "dangling stereotypes") even though the correct version of the profile is properly applied. Reasons may be bad merges or bugs in the software, but the result is objects in the model resource that are no longer stereotype applications because they do not extend any model element.

The Stereotype Application Repair function can resolve or otherwise address all of these problems.

Invocation of Stereotype Application Repair

Papyrus scans all UML model resources when they are loaded to look for problems with stereotype applications. If any are found, the Repair Stereotypes dialog opens automatically to let the user fix them.

For each discrete XML namespace in a resource that has a problem, the dialog presents:

• the resource in which the problem is found
• the number of stereotype applications affected
• the name of the profile that defines the affected stereotypes. If the profile cannot be found automatically, a name is inferred from the XML namespace name (this is indicated by the "unknown schema" annotation as shown in the figure above
• the available actions for resolution of the problem

The dialog may be cancelled at any time, in which case no further action will be taken until the next time the repair dialog is launched. Any problems for which a repair action is selected (being not the Postpone action; see below) may be repaired by pressing the Apply button. The dialog will then remain open to continue with the remaining problems. Or press OK to apply all selected actions (including Postpone) and close the dialog.

The complete set of actions available for fixing a group of stereotype applications is

• Migrate Profile: if the profile defining the stereotype applications can be determined automatically, in the case where the problem is simply that a different version of the profile is applied to the model, this action migrates the stereotype applications to the currently applied profile definition. Otherwise, the user is asked to find the profile (either in the workspace or registered by an installed plug-in) and that profile is applied to the model, implicitly migrating the stereotype applications to its current definition
• Create Markers: this action does not change the model or the stereotype applications in any way but simply creates a problem marker for each affected model element as a reminder that there is an unresolved problem in its applied stereotype
• Delete Stereotypes: this action deletes the affected stereotype applications. Use it when the profile simply no longer exists or is otherwise obsolete and no longer required by the model
• Postpone: this action simply does nothing. Fixing the problem is deferred to the next time that Papyrus scans the resource for problems in stereotype applications

The dialog initially suggests the best available repair action for each group of broken stereotype applications. Usually this is the Migrate Profile action, which has the best chance of fixing the problem and not losing valuable information from the model. However, in the case of dangling stereotypes (which have become disconnected from the UML elements that they extend), the Migrate Profile action is not available and Delete Stereotypes is suggested instead. This is because these objects are not actually stereotype applications, being not extensions of any UML element, and so there is nothing to repair. If it happens that the elements they were meant to extend still exist and they need to be reconnected, then Papyrus cannot determine two which elements they should be reconnected. In that case, the user must simply take the Postpone option and fix up these objects' base element references by some other means.

Model Validation

Papyrus contributes a model validation constraint, enabled by default, that scans the model's stereotypes for problems when the entire model is validated. This uses the same repair analysis capability described above. Problems reported by this constraint have a "quick fix" available in the Model Validation view and in the Problems view that launches the same dialog described above for resolution of stereotype application issues.

This is useful, for example, after completing a compare/merge operation, profile migration, or other complex operation that may have resulted in structural problems in the model (whether in stereotype applications or otherwise).