automatic generation of model traversals from metamodel definitions authors: tomaž lukman, marjan...
DESCRIPTION
Introduction Modeling is an important part of software engineering Model-Driven Engineering (MDE) promotes the systematic and disciplined use of precise models throughout the software lifecycle Increases productivity and software quality Domain-Specific Modeling Languages (DSMLs) – use concepts (e.g., terms, symbols and pictures) and abstractions that are common to a specific domain MDE needs tool support to enable various development tasks with a specific DSML model editor, model debugger, test suite, interpreters Without tool support a DSML can become obsolete 3/18TRANSCRIPT
AUTOMATIC GENERATION OF MODEL TRAVERSALS FROM METAMODEL DEFINITIONS
Authors: Tomaž Lukman, Marjan Mernik, Zekai Demirezen, Barrett Bryant, Jeff Gray
ACM SE ‘10, Oxford, MS, 4/17/2010
FACULTY OF ELECTRICALENGINEERING ANDCOMPUTER SCIENCEMaribor, Slovenia
Jožef Stefan Institute,Ljubljana,Slovenia
Agenda Introduction Research problem Research objectives Related work Proposed approach
Specification of semantics Model traversal algorithm
Example Conclusion
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Introduction Modeling is an important part of software
engineering Model-Driven Engineering (MDE) promotes the
systematic and disciplined use of precise models throughout the software lifecycle Increases productivity and software quality
Domain-Specific Modeling Languages (DSMLs) – use concepts (e.g., terms, symbols and pictures) and abstractions that are common to a specific domain
MDE needs tool support to enable various development tasks with a specific DSML model editor, model debugger, test suite, interpreters
Without tool support a DSML can become obsolete
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Model-Driven Engineering (MDE)
MDE: specifies and generates software systems based on high-level models
Domain-Specific Modeling (DSM): a paradigm of MDE that uses notations and rules from an application domain
Metamodel: defines a Domain-specific Modeling language (DSML) by specifying the entities and their relationships in an application domain
Model: an instance of the metamodel
Model Transformation: a process that converts one or more models to various levels of software artifacts (e.g., other models, source code)
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Research problem DSMLs are not defined precisely
The potential benefits of MDE cannot be achieved Semantics are the most challenging part of a
DSML definition State-of-the-practice: semantics are specified
with model interpreters Low understandability Model-based tools cannot be automatically
generated (e.g., code interpreters, debuggers) Manual development of model-based tools is
time consuming, error prone and expensive Challenge: How to generate model based tools
automatically?
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Research objectives Analogy: in the field of programming languages,
language-based tools can be automatically generated E.g., attribute grammars -> debuggers, animators,
test suites Broad objective: Development of a formalism for
semantics from which model based tools can be automatically generated
Current work: The generation of model interpreters
What is needed for the generation of model interpreters: A formalism to specify the semantics An algorithm to traverse the model and generate the
parser
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Semantics specification for modeling languages
State-of-the-art: several proposals for specifying the semantics of modeling languages already exist
Translation semantics: semantics are defined trough a mapping into formalism with well-known semantics (e.g., Abstract State Machines) Drawback: backward mapping of computation results
Weaving behavior: an action language specifies the bodies of the operations in the metamodel Drawback: action languages are imperative
Semantics based on rewriting systems: operational approach for defining through rewrite rules e.g., graph grammars
Issue: None of the proposed approaches focuses on the automatic generation of model-based tools
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Proposed approach Idea: extend metamodels with semantic
information Similar to attribute grammars in programming
languages Consists of two parts:
Information about semantics in the metamodel
= specification of semantics Automatic synthesis of this information to
generate model based tools = traversal algorithm
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Specification of semantics The semantics is specified with semantic attributes and semantic
rules Semantic attribute – associate with each
metaclass Semantic rules - carry semantic information
that specifies how semantic attributes are calculated Currently specified through Java
The meaning of the model will be obtained by evaluating attribute occurrences The initial value of the attribute is undefined Redefined by the traversal algorithm during its execution They are used to obtain/compute the meaning of the whole model
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Model traversal algorithm A traversal algorithm over models (graphs) is needed to
evaluating semantics attributes based on semantic rules The algorithm depends on the metamodel and the API
(application programming interface) of the model repository
Example of modeling environments: GME (Generic Modeling Environment) GMF (Graphical Modeling Framework)
We developed an initial algorithm that works with EMF (Eclipse Modeling Framework) Optimized and extended to other environments in the future
The development of the traversal algorithm represents the most challenging part of our approach
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Development of the model traversal algorithm (1/3) The requirements for the model
traversal algorithm: i. All model elements should be visitedii. Avoidance of endless loops iii. It must find the start element of the
modeliv. Executabiltiy on disconnected models
(there are some modes that are not connected to other nodes)
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Development of the model traversal algorithm (2/3) Interpreters are developed based on the metamodel
nodes and relationships between them We specified: what the algorithm should do (i.e.,
where to navigate) when a specific relationship occurs The types of relationships in Ecore (EMFs
metamodeling language): Root metaclass – traverse all
traversable relationships
Unidirectional metarelationship – traverse into one direction (where arrow is pointing)
Bidirectional metarelationship – traverse in both ways
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Development of the model traversal algorithm (3/3)
To use an algorithm based on these simple rules we have to use metamodels that satisfy this requirements: The root metaclass should not be connected to each other
with any relationship except the composition relationship Bidirectional metarelationships are not used
Composition metarelationship – traverse away from the composition
Generalization metarelationship – traverse down the inheritance tree
Root metaclass with a self-containing metarelationship – traverse away from the filled diamond until the current instance is the root
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The developed traversal algorithm Based on the previous
design decisions we havedefined the following algorithm:
modelRoot = findAbsoluteModelRoot();visit(modelRoot);
// recursive visiting functionfunction visit(currentModelElement)
// evaluate the current nodeevaluateInheritedAttributes();// visit possible generalizations – top downif currentModelElement has subMetaclasssubMetaclassOfCurrent = getSubMetaclass(currentModelElement);visit(subMetaclassOfCurrent);end-if
// visit possible unidirectional relationshipsforeach unidirectionalRel in currentModelElementif unidirectionalRel.source == currentModelElement evaluateInheritedAttributes();foreach modelElement in unidirectionalRel.targetvisit(modelElement);end-foreachevaluateSynthesizedAttributes();markPathAsVisited();end-ifend-foreach
// visit possible composition relationshipsforeach compositionRel in currentModelElementif compositionRel.source == currentModelElement evaluateInheritedAttributes();foreach modelElement in compositionRel.targetvisit(modelElement);end-foreach evaluateSynthesizedAttributes();markPathAsVisited();end-ifend-foreachevaluateSynthesizedAttributes();
end-function
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Example (1/2) We demonstrate our approach on the finite
state machine (FSM) modeling language (metamodel below)
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Example (1/2) According to our algorithm and the semantic
specification, the following interpreter can be generated:modelRoot = StateMachine();
modelRoot->TransitionList.envt=new EList();modelRoot->AbstractState.envs=new EList();
foreach AbstractState in modelRoot->statesif notVisited() AbstractState.envs.insert(AbstractState.text); markPathAsVisited();end-ifend-foreach
foreach Transition in modelRoot->statesif notVisited() Transition.envt.insert(Transition.src, Transition.dst); markPathAsVisited();end-ifend-foreach
modelRoot.code = compute(AbstractSate.envs, Transition.envt);
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Conclusion Identified the need for automatic generation
of model-based tools Proposed a semantics specification, which
allows the generation of model interpreters Consists of a semantics definition and a
traversal algorithm Showed a FSM example that uses our
approach This was our first step towards the theory of
generating various model based tools from DSML definitions
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