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EMF Compare/CompareUMLPapyrusAPI

Some of this work are sponsored by Ericsson

Enhance the existing tree editor

  • Specific team handler for model resources managed through Git with eGit. This handler enables the comparison and merge of files managed with Git.
  • Capability to switch between the tree and textual editor by using a popup menu, without losing the selection.
  • Capability to restrict the comparison on the current selection
  • Capability to group differences by:
    • File
    • Modification type
    • Meta model element
    • Flat text elements (?)
  • Capability to dynamically hide/show the displayed elements with filters:
    • Filter add changes
    • Filter delete changes
    • Filter modify changes
    • Filter element order changes
  • Propose a Preference page to define default settings for EMF compare filter
  • Provide an API enabling the contribution of new filters.

Specific support of UML Model

In order to provide the best possible accuracy and precision when comparing and merging UML models, it is necessary to implement a specific comparison engine which handles the UML meta-model directly (according to the UML metamodel defined with EMF in Eclipse / Modeling Tools / UML).

For example, for the addition (or deletion or modification) of an association at the UML level, there is 3 additions (or deletions, or potential modifications) in the EMF representation : one "association", and two "property ends". We will define specific UML extensions for EMF Compare using the DiffExtension API to create the UML level operations (AddAssociation, DeleteAssociation, ModifyAssociation) and write the recognition code to identify these UML level change operations from the EMF level change operations. So, the end-user who diffs and merges a UML model will only see UML level change operations, and the changes will be applied atomically on the model to avoid model inconsistency.

Additionally, EMF Compare will support diff and merge of fragmented UML models, that is UML models stored in several physical resources, and of sets of UML model fragments. The fact that UML level operations are atomically applied will be specifically addressed in the case of merging of model fragments to forbid partial merges in one fragment that would corrupt the whole model.

Another transversal UML issue to be addressed is the support of UML profiles.

We will also ensure that generic APIs are adapted to work at the UML level. More specifically, we will provide UML level APIs for:

  • API to request a UML diff between two models providing the result as a list of structural differences or serialized to a file
  • API to retrieve the UML modification types (e.g. add, delete, change, move, separation/fragment, join/fragment)

Then, we identify separate sets of UML diagram meta-models which will be supported incrementally:

  • Support first set of Structural metamodels : Package, Class
  • Support second set of structural metamodels : Composite
  • Support first set of behavioral metamodels : Use Case , Sequence, Activity
  • Support second set of behavioral metamodels : State, Communication

GMF Diagram Comparison

With diagram comparison, a user must be able to graphically visualize the changes between two or three diagrams. Diagram comparison will contribute a new comparison editor, in addition to the tree and textual comparison editors. This new editor will be available when the compared resources are GMF diagrams. Typically, the diagram comparison editor will display one version of the diagram without decoration (the original diagram) alongside another version of the diagram with graphical decorations to show the differences.

  • Additions of nodes or edges must be highlighted with a specific graphical decoration.
  • Modifications of nodes and edges must be highlighted with a specific decoration.
  • Layout changes must be displayable, but must also be filtered with a configurable threshold. This threshold must be configurable either through an API, or an Eclipse preference.

Support fo various UML diagrams comparison in Papyrus

Beyond the generic implementation of GMF graphical diagrams comparison, we will integrate diagram comparison in the Eclipse foundation open source tool Papyrus. We will incrementally implement the different diagrams supported in Papyrus:

  • Support first set of Structural diagram metamodels : Package, Class
  • Support second set of structural diagram metamodels : Composite
  • Support first set of behavioral diagram metamodels : Use Case , Sequence, Activity
  • Support second set of behavioral diagram metamodels : State, Communication

A specific communication and contribution channel will be established to ensure that the UML model comparison is integrated with the mainstream Papyrus releases.

Others generic APIs

The following APIs will be implemented to work both with the Tree and diagram comparison editors:

  • API to create a viewer listing all structural changes resulting from a model comparison which includes the filtering and grouping options as mentioned previously. This API will offer the capability to programmatically retrieve the Meta model class (type) e.g. Documentation, stereotype)
  • API to query the viewer for the list of visible changes (e.g. not filtered out) The type of elements returned in the list of structural differences should offer an API to retrieve the location information of the affected elements, in order to trigger the selection of the affected elements in both the Project Explorer and Editor.
  • API to handle and serialize a set of graphical elements under comparison so that it is possible to pass them on to another tool.
  • API to launch an Eclipse Model Compare editor with two specified versions of model files and be able to programmatically request the selection of a structural change based on a previously obtained location.

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