Talk given at the EXE (EXEcutable Models) workshop from MODELS'2015.

1. Coping with Semantic Variation Points in
Domain-Specific Modeling Languages
1st International Workshop on Executable Modeling (EXE 2015)
MODELS 2015 Workshops
Florent Latombe1
Xavier Cr´egut1
Julien De Antoni2
Marc Pantel1
Benoˆıt Combemale3
1
University of Toulouse, IRIT, Toulouse, France
first.last@irit.fr
2
Univ. Nice Sophia Antipolis, CNRS, I3S, Inria, Sophia Antipolis, France
first.last@polytech.unice.fr
3
University of Rennes I, IRISA, Inria, Rennes, France
first.last@irisa.fr
2015/09/27

2. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Table of contents
Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 2/36

3. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
Overview
Introduction
Context: xDSMLs
Semantic Variation Points
Concurrency and SVPs
Implementing SVPs
Conclusion
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 3/36

4. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
eXecutable Domain-Specific Modeling Languages
(xDSMLs)
Modern systems: Too big to be addressed only as a whole.
Domain-Specific Languages (DSLs) capitalize domain knowledge
(security, fault tolerance, etc.) as language constructs.
Modeling Languages (MLs) provide user-friendly abstractions for
domain experts.
eXecutable DSMLs ease the design, verification and validation of modern
systems.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 4/36

5. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
Overview
Introduction
Context: xDSMLs
Semantic Variation Points
Concurrency and SVPs
Implementing SVPs
Conclusion
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 5/36

6. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
Semantic Variation Points
Semantic Variation Point (SVP) language specification part left intentionally
under-specified to allow further language adaptation. Usually dealt with:
Further refinement of the specification (e.g., stereotypes or profiles in
UML).
Arbitrary choices in the implementation (e.g., multithreaded programs in
CPython or Jython, fUML, etc.).
Tool vendors responsible for specifying and documenting the
implemented solution.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 6/36

7. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
Example: priorities of conflicting transitions in
Statecharts
Figure 1: Simple music player statechart.
When Event “StopEvent” occurs in
States “On” and “Playing”.
Original formalism: Transition
from “On” to “Off” is fired.
UML/Rhapsody: Transition from
“Playing” to “Paused” is fired.
Courtesy of the comparative study of the dif-
ferent Statecharts dialects and their SVPs by M.
Crane and J. Dingel [3].
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 7/36

8. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
Vocabulary Clarification
Language: syntax and semantics specification that may contain SVPs.
Dialect: language implementation, making choices about some – possibly
all – its SVPs.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 8/36

9. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
Problem
SVPs usually identified informally in the syntax and semantics
specification documents.
Tools usually only provide one dialect, constraining the end-user.
Complicates cooperation between tools (providing different dialects) and
users (who may assume different meanings for the same syntax).
Hinders cooperation in larger projects using different variants of the
same language that may be better fit for some aspects.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 9/36

10. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Context: xDSMLs
Semantic Variation Points
Summary of our Contribution
A concurrent executable metamodeling approach enabling the
specification of Concurrency-aware eXecutable Domain-Specific
Modeling Languages.
Specification of operational semantics that makes explicit the language
concurrency concerns in an adapted formalism based on concurrency
theory.
That allows to explicitly specify and implement xDSML’s SVPs.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 10/36

11. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Overview
Introduction
Concurrency and SVPs
Concurrency-aware xDSMLs
Statechart Example
Implementing SVPs
Conclusion
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 11/36

12. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Designing xDSMLs
Language design
Language AS + SD + M(AS, SD) Where:
Abstract Syntax (AS): concepts and relations between concepts
Semantic Domain (SD): meaningfull existing language
Semantic Mapping (M(AS, SD)): maps concepts from the AS to their
meaning in the SD.
Three main approaches to the Semantic Mapping: Axiomatic, Translational
(incl. Denotational) and Operational.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 12/36

13. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Overview of the GEMOC Approach
Separation of Concerns
(SLE 2013 [2])
Split the Semantic Mapping in:
Semantic Rules: Operational
specification of the model
runtime state evolution.
Concurrency Model: Partial
ordering of abstract actions in a
formalism inspired by
concurrency theory.
Communication Protocol: Relates
abstract actions and Semantic
Rules.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 13/36

14. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Concurrency Model
Called Model of Concurrency
and Communication (MoCC) in
GEMOC.
Focuses on concurrency,
synchronization and the, possibly
timed, causalities between
actions.
Actions are opaque (data
manipulations are abstracted).
Given as an EventType Structure
which builds the Event
Structure [10] for each model
concurrent control flow.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 14/36

15. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Communication Protocol
Relates the Concurrency Model
and the Execution Functions
See Weaving Concurrency in
eXecutable Domain-Specific
Modeling Languages (SLE
2015) [8].
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 15/36

16. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Class Diagram of the concurrent executable
metamodeling approach
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 16/36

17. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Execution
Translation
Model-specific specifications are generated (i.e., Semantic Rules,
Communication Protocol and MoCC all specific to the given model).
Runtime
The Event Structure (MoCC at the model level) gives a partial ordering
over abstract events.
Abstracts all the possible model executions paths (including all
interleavings of concurrent events).
Event occurrences are mapped to model runtime state changes by the
Communication Protocol.
Nondeterministic situations are resolved by runtime heuristics.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 17/36

18. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Overview
Introduction
Concurrency and SVPs
Concurrency-aware xDSMLs
Statechart Example
Implementing SVPs
Conclusion
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 18/36

19. Event Structure for our example model
At the Language Level
Main EventTypes:
Event.et occur,
Transition.et fire
Main constraints: When anEvent
occurs, one of the Transitions it
triggers will be fired.
Event Structure
Nodes
areconfigurations:
Unsorted set of
event occurrences
which occured at
this execution
point.

20. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Concurrency-aware xDSMLs
Statechart Example
Illustration of the Separation of Concerns at the
model level
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 20/36

21. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
SVPs and Concurrency Models
Example: Statecharts
Overview
Introduction
Concurrency and SVPs
Implementing SVPs
SVPs and Concurrency Models
Example: Statecharts
Conclusion
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 21/36

22. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
SVPs and Concurrency Models
Example: Statecharts
Event Structures and SVPs
Nondeterminism in Event Structures gives potential SVPs.
SVPs can be implemented by constraining the Event Structure partial
ordering.
Done at the language level in the EventType Structure.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 22/36

23. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
SVPs and Concurrency Models
Example: Statecharts
Overview
Introduction
Concurrency and SVPs
Implementing SVPs
SVPs and Concurrency Models
Example: Statecharts
Conclusion
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 23/36

24. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
SVPs and Concurrency Models
Example: Statecharts
Example: Conflicting Transitions SVP
Main Idea
Most of the concurrency concerns are shared by Statecharts dialects.
Statecharts MoCC specifies the superset of possible partial orderings.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 24/36

25. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
SVPs and Concurrency Models
Example: Statecharts
Example: Conflicting Transitions SVP (2)
SVP Implementations
Dialects extend the common MoCC to restrict partial orderings.
Removes On2Of for UML/Rhapsody dialects, and Playing2Paused for
Original dialect.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 25/36

26. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Overview
Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 26/36

27. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Implementation
GEMOC Studio1
implementation based EMF [7].
Abstract Syntax: Ecore (EMF implementation of EMOF [9]).
Semantic Rules: Kermeta 3 [6] (based on Xtend [1]).
Concurrency Model: MoCCML [4] and ECL [5].
Communication Protocol: Gemoc Events Language (GEL) [8].
1http://www.gemoc.org/studio
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 27/36

28. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Overview
Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 28/36

29. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Overview of our contribution
SVPs are usually poorly identified in language specifications.
GEMOC concurrent executable metamodeling approach, based on Event
Structure for the Concurrency Model of concurrency-aware xDSMLs
provides potential SVPs as nondeterministic situations.
Restricting the partial ordering defined in the Concurrency Model
implements SVPs.
SVP implementations are weaved in the language definition, allowing the
execution tool to remain independent from any arbitrary choice.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 29/36

30. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Overview
Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 30/36

31. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Perspectives
Distinguish wanted nondeterminism from potential SVPs (forbid
restrictions).
Other kind of SVPs using Semantic Rules and/or Communication
Protocol.
Integration with SVPs at the syntax level, both abstract and concrete.
Experiment the use of variability management techniques to handle
dialects.
Acknowledgement
This work is partially supported by the ANR INS Project GEMOC
(ANR-12-INSE-0011).
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 31/36

32. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Overview
Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 32/36

33. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
Thank you for your attention.
Questions?
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 33/36

34. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
References I
L. Bettini.
Implementing Domain-Specific Languages with Xtext and Xtend.
Packt Publishing Ltd, 2013.
B. Combemale, J. De Antoni, M. Vara Larsen, F. Mallet, O. Barais,
B. Baudry, and R. France.
Reifying Concurrency for Executable Metamodeling.
In SLE 2013, LNCS. Springer-Verlag.
M. L. Crane and J. Dingel.
UML vs. Classical vs. Rhapsody statecharts: not all models are created
equal.
SoSyM, 2007.
J. De Antoni, P. Issa Diallo, C. Teodorov, J. Champeau, and B. Combemale.
Towards a Meta-Language for the Concurrency Concern in DSLs.
In DATE’15, Mar. 2015.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 34/36

35. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
References II
J. De Antoni and F. Mallet.
ECL: the event constraint language, an extension of OCL with events.
Technical report, Inria, 2012.
DIVERSE-team.
Github for K3AL, 2015.
Eclipse Foundation.
EMF homepage, 2015.
F. Latombe, X. Cr´egut, B. Combemale, J. Deantoni, and M. Pantel.
Weaving Concurrency in eXecutable Domain-Specific Modeling
Languages.
In 8th ACM SIGPLAN International Conference on Software Language
Engineering (SLE 2015), Pittsburg, United States, Oct. 2015. ACM.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 35/36

36. Introduction
Concurrency and SVPs
Implementing SVPs
Conclusion
Implementation
Overview
Perspectives
Questions
References III
OMG.
MOF specification v2.5, 2015.
G. Winskel.
Event structures.
Springer, 1987.
F. Latombe, X. Cr´egut, J. De Antoni, M. Pantel, B. Combemale Coping with Semantic Variation Points in DSMLs 36/36