EMF Compare is a framework supporting model differencing and merging for EMF-based models. Therefore, it enables users to determine changes they have applied to their models, to identify overlaps between distinct models and to merge changes that have been performed on the same model by different users in parallel. However, in many modeling projects, the modeling languages and tools for showing and editing models are tailored to the specific needs of the targeted users. Typical customizations range from domain-specific model editing UIs, such as diagrams or form-based UIs, to modeling macros that allow users to make many model changes with one click. If you apply EMF Compare in such customized modeling environments as is, the results cannot and will not be satisfactory out-of-the-box. EMF Compare is and can only be an extensible framework rather than a one-size-fits-all tool. In this talk, we show you how you can add tailor-made model comparison capabilities to your modeling project by customizing and integrating EMF Compare in various ways. We explain the extension mechanisms based on examples from customizations that we have actually developed for Papyrus UML and domain-specific form-based modeling projects.

1. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 1
Tailor-made model comparison:
How to customize EMF Compare
for your modeling language
Philip Langer <planger@eclipsesource.com>
Laurent Delaigue <laurent.delaigue@obeo.fr>
Maximilian Koegel <mkoegel@eclipsesource.com>

2. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 2
● Comparing and merging EMF-based models
○ Obtaining differences among model versions
■ Two-way differencing
■ Three-way differencing
○ Merging concurrently modified model versions
○ Merge viewers
■ Showing differences
■ Merging differences
■ Resolving conflicts
○ Integration with Eclipse team providers, such as EGit
○ Ships with dedicated support for Papyrus UML and GMF
EMF Compare + EGit =

3. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 3
The way how you model...

4. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 4
… should be as close as possible to how you compare/merge them

5. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 5
● Raise the unit of comparison from text line to model elements
● Compare and merge the logical structure of the models
● EMF Compare’s core is built with generic algorithms
○ Make use of the metamodel to obtain knowledge on logical structure
○ Reflective API to access and compare values generically
○ Support every modeling language that is specified in EMF
How does EMF Compare work?
Model
(model.uml)
Metamodel
(UML.ecore)
EMF’s
reflective
API
EObject
EReference
EAttribute
...

6. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 6
● Model comparison phases
○ Matching
Finding corresponding model elements
○ Diffing
Identifying differences among
corresponding model elements
○ Analysis of differences
Equivalences, dependencies, and
conflicts among differences
How does EMF Compare work?

7. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 7
● Model comparison phases
○ Matching
Finding corresponding model elements
○ Diffing
Identifying differences among
corresponding model elements
○ Analysis of differences
Equivalences, dependencies, and
conflicts among differences
How does EMF Compare work?

8. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 8
● Model comparison phases
○ Matching
Finding corresponding model elements
○ Diffing
Identifying differences among
corresponding model elements
○ Analysis of differences
Equivalences, dependencies, and
conflicts among differences
How does EMF Compare work?

9. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 9
● Model comparison phases
○ Matching
Finding corresponding model elements
○ Diffing
Identifying differences among
corresponding model elements
○ Analysis of differences
Equivalences, dependencies, and
conflicts among differences
How does EMF Compare work?

10. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 10
● Gap between what EMF Compare processes and what users see
○ EMF Compare only “knows” the abstract model and the metamodel
○ Users only know how to use the modeling editor
When and why is customization needed?
Model
(model.uml)
Metamodel
(UML.ecore)
EMF’s
reflective
API
EObject
EReference
EAttribute
...
Papyrus

11. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 11
● Gap between what EMF Compare processes and what users see
○ EMF Compare only “knows” the abstract model and the metamodel
○ Users only know how to use the modeling editor
When and why is customization needed?
Model
(model.uml)
Metamodel
(UML.ecore)
EMF’s
reflective
API
EObject
EReference
EAttribute
...
Hides complexity
of the modeling
language
Provides domain-
specific view of
the model
Offers composite
actions and
types
I have never
seen the
metamodel!

12. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 12
● Gap between what EMF Compare processes and what users see
○ EMF Compare only “knows” the abstract model and the metamodel
○ Users only know how to use the modeling editor
When and why is customization needed?
Model
(model.uml)
Metamodel
(UML.ecore)
EMF’s
reflective
API
EObject
EReference
EAttribute
...
The relative customization distance

13. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 13
● EMF Compare is a highly-customizable framework
○ Enabling us to implement tailor-made model comparison tools
○ Take generic support of EMF Compare and make it domain-specific
● Customization and extension points: EMF Compare Core
Customizing EMF Compare
Matching Diffing Analysis of Diffs Merging
Match Engine
Match Strategy
Diff Engine
Feature Filter
Equivalence Engine
Requirements Engine
Conflict DetectorWeight Provider
Merger
Post-processor Post-processor Post-processor

14. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 14
Customizing the EMF Compare Merge Viewer

15. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 15
Customizing the EMF Compare Merge Viewer
Group providers specify the content of this tree over a comparison
Default providers can be customized
Additional group providers
can be added for more options
Filters
can be added and auto-activated
or just added as option for users
Elements have to adapt to a type
Double-clicking an element will
open the content merge viewer for
the respective type
Content merge viewers
One or more content merge
viewers can be provided for a
defined type

16. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 16
● Library example
○ Additional filter
○ Additional domain-specific grouping option
○ New difference type
● Other model viewer
○ Custom content merge viewer
Demos of Example Customizations

17. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 17
● It isn’t possible to build a one-size-fits all model comparison tool
○ Difference viewer should be as close as possible to how users work
○ Customized modeling editor → customized model comparison tool
● Build a highly extensible and well-performing basis
○ Make extending EMF Compare as easy as possible
○ Maximize the reuse of knowledge from the modeling editor
● Build a perfect ready-to-use model comparison tool
○ For Papyrus UML, UML-RT, and SysML on top of EMF Compare
→ http://www.collaborative-modeling.org
Future Perspectives

18. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 18
● More information
○ EMF Compare Developer Guide
○ EMF Compare Forum
○ Contact us
● Follow us on http://www.collaborative-modeling.org
Thank you very much!

19. © 2015 EclipseSource | http://eclipsesource.com/vienna | Philip Langer et al. | Tailor-made Model Comparison 19
● Follow us on http://www.collaborative-modeling.org
Thank you very much!