A novel approach to modeling Zvezdan Protić, Tom Verhoeff, Mark van den Brand

Preliminaries  MDSE  Models  A model is an abstraction of System Under Study (SUS) that can be used for reasoning about that SUS  Metamodels  Syntactic carrier of models  Metametamodels

Popular Metametamodels having “layered” architecture PAGE 3  MOF (UML)  Ecore (Eclipse)  GME (Generic Modeling Environment) metametamodel

Some reasons for a new approach  In traditional modeling approaches a metametamodel is an instance of itself  Thus, conceptually, an > relation can have two interpretations  But those interpretations are not clearly stated for traditional metametamodels  “A metamodel is simply the model of a model, and if that model is itself a metamodel, then the metamodel is in fact a meta-metamodel.[4] Got it? If not, don't worry about it, as it's really just an academic issue anyway.”  EMF Eclipse Modeling Framework (2 nd Edition)  The relationship instantiation problem  E.g. in MOF the instance of an > is a >  But link does not contain attributes of association, e.g. cardinalities, unless it inherits from >, thus an instance of a link cannot be used as a link again

> problem of the layered architecture PAGE 5

Our MetaMetaModel PAGE 6

Example Metamodel PAGE 7 State Transition Label:String From To0..1

Example model (with relations to its metamodel) PAGE 8 AB SM1

Similarities to UML 2.4

Implementing a layered architecture in our approach PAGE 10 MetaMetaModel MetaModel2 Model2 conforms-to instance-of MetaModel3Model3 ModelMetaModel conforms-to Transform (interpret) conforms-to Transform (interpret) instance-of

Why is our approach a plausible approach?  Ethan K. Jackson, and Janos Sztipanovits: Formalizing the Structural Semantics of Domain-specific Modeling Languages, Journal of Software and System Modeling, 2009  An algebraic approach to defining the syntax and structural semantics of domain specific modeling languages (DSML)  A DSLM is a pair of a domain and interpretations.  A domain is specified similar to a language as a tuple of: concepts that can be used to build models (Y), a set of all realizations of models (RY), and a set of constraints over RY  Concepts, are described by using term algebras  Constraints are described by using formulas of a logic  Terms can be transformed into formulas  The validity of a model is checked by making a deductive closure of an union of constraint formulas and term formulas  An interpretation is a transformation from a domain to a domain  Formally, an interpretation is a triple of source domain signature, a target domain signature, and the set of formulas in the same logic as the one used to specify constraints  A metametamodel is just another domain, that has, as concepts, all the concepts that can be used in other domains  This means it is very easy to change the metametamodel  A metamodel is a model of a metametamodel, such that there is an interpretation that can generate a domain based on that metamodel  A metametamodel is meta-circular if it has a realization that when interpreted into a domain, can be interpreted back into the metametamodel domain

Applications  Model comparison  Metamodel and Model co-evolution

Metamodel-independent model comparison  A model comparison is the process of determining differences between two models  Model differences are represented by a another (differences) model that conforms to a differences metamodel  The model repositories are bound to have large number of metamodels that models conform to  Metamodel-dependent model comparison may not suffice

Our approach to model comparison: metamodel of model differences

Metamodel independent metamodel and model co-evolution MM1_v1MM1_v2 M1M1_v2 conforms-to evolution conforms-to co-evolution

A common approach to co-evolution

Why we propose SOT-s  An example operation: Make Reference Composite  What are some possible solutions:  Copy all referenced entities into the new containers?  Move all referenced entities into the new containers?  Assign all entities of the referenced type to containers of the referees?  Or let the user decide which entities should stay in old containers, and which entities should move ?

Metamodel for metamodels PAGE 18

An example metamodel in “natural” and “transformed” representation PAGE 19

Advantages of our approach  All the atomic differences between metamodels are known  Thus, we can create one transformation that co-evolves models  By using SOT, the users that are co-evolving models can easily adapt the transformation to a particular situation

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