Language Specification using Metamodelling

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Language Specification using Metamodelling

• Joachim Fischer
• Humboldt University Berlin

LAB Workshop Geneva 24.11.02
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Languages ...

• cover domains, not the universe
• ? complex systems need more than one language
  (SDL, ASN.1, ...) for their description,
  implementation, deployment, ...
• are driven by user needs (concepts, notations)
• ? evolution
• need notations
• ? graphical notation in favour
• state of the art (SDL, TTCN, MSC, URN, ...)
• best suited to cope with complexity (2
  dimensional drawing text)
• clear representation (better than text)
• often share similar concepts (OO concepts, ODP
  concepts...)
• need tools to be used !
• need a community to live and to evolve !

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Language Definitions ...

• differ in the level of formality
• "traditionally" use grammars
• concrete grammar for definition of notations
• abstract grammar for definition of concepts
• do not share the grammar with other languages
• "new" Metamodelling approach use graphs
  (labelled nodes and arcs)
• graphs for definition of concepts
• assignment of notation elements (informal,
  formal)
• differentiation of abstraction levels model and
  Metamodel
• concept of Metamodelling in general is not new
  but for the definition of languages!
• Similarities between both?

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"New" versus "Traditional"
"traditional" Layer
Description
"new" Layer
Meta- Metamodel
infrastructure for - language definitions
- Metamodelling architecture
M3

• - instance of M3
• - language for specification of / programs /
  models
• - semantic definition

- instance of M2 - language for description of
an information domain
- instance of M1 - real subject of existence
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Semantic Concerns
"traditional"
"new"

• grammar
• wellformedness rules (text,ASM )
• ASM,

• M3 implications
• wellformednessrules (text,OCL, )
• mapping tolanguages
• ASM,

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Characteristics of Metamodelling

• language definition in M2 layer (Metamodel)
• defines concepts
• may be manipulated (Extension, Specialization,
  Structural adaptation)
• definition of semantic separated from language
  notation
• no coupling to grammar technologies
• suitable (graphical) notation can be selected!
• integration of languages with different notations
  is possible
• common Meta-metamodel is a suitable way for a
  language integration
• relations between metamodels (SDL ?? UML),
• construction of a merged Metamodel (language) is
  possible

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MOF - Meta Object Facility

• OMG standard
• base of OMG Model Driven Architecture (MDA)
• What is it ?

• model driven distributed object framework
• specification
• construction
• management
• exchange
• integration
• integrating
• of Metadata in software systems

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MOF - Meta Object Facility

• OMG standard
• base of OMG Model Driven Architecture (MDA)
• What is it ?

• model driven distributed object framework
• specification
• construction
• management
• exchange
• integration
• integrating
• of Metadata in software systems

• Concept Space
• fundamental object oriented terminology
• classes, associations, inheritance, packages
• common modelling concepts similar to
  UML-Core (more restricted)

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MOF - Meta Object Facility

• OMG standard
• base of OMG Model Driven Architecture (MDA)
• What is it ?

• model driven distributed object framework
• specification
• construction
• management
• exchange
• integration
• integrating
• of Metadata in software systems

• MOF Repository as a Tool
• offers I/f for storing and processing of
• Metamodels (based on MOF concepts)
• models (based on those Metamodels)

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MOF - Meta Object Facility

• OMG standard
• base of OMG Model Driven Architecture (MDA)
• What is it ?

• model driven distributed object framework
• specification
• construction
• management
• exchange
• integration
• integrating
• of Metadata in software systems

• XML representation ensures
• exchange of Metamodels and models,
  independend from
• - syntactical representation
• MOF-tool-vendor
• ORB vendor

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MOF - Meta Object Facility

• OMG standard
• base of OMG Model Driven Architecture (MDA)
• What is it ?

• model driven distributed object framework
• specification
• construction
• management
• exchange
• integration
• integrating
• of Metadata in software systems

• usage of the same Metameta-model
• as a base for
• relating Metamodels
• representing concepts of different languages
• comes with the result of
• an integrated language
• on conceptual level nothing is said about a
  common notation !!!

but MOF does not define the style of notations
! MOF 1.x comes only with textual
description of MOF
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• if UML is used for concrete MOF syntax, UML
  tools can used for that new language too

UML, IDL, EDOC, ...
eODL, TTCN-3, URN, SDL ???
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Benefits of MOF (1)

• MOF repository stores metamodels
• access via IDL interfaces
• generic interfaces for inspection and traversal
• model specific interfaces according to MOF
  concepts
• tools can obtain information about the language
• tools can add information (implemented language
  subset)
• same interfaces for all metamodels (languages)!

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Benefits of MOF (2)

• MOF-to-IDL mapping generates repositories
• IDL for Metamodel specific repository
• serve to
• store,
• manipulate,
• retrieve and
• exchange models
• standard API for modelling tools
• Similar to MOF-IDL
• same technology for allmetamodels (languages)!

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Benefits of MOF (3)

• MOF-XMI provides file/streaming format
• XML Metadata lnterchange
• XMI defines a DTD for MOF
• Metamodels can be exchangedas XML file/stream
• XMI defines rules to createDTDs for Metamodels
• Model can be exchanged as XML file/stream (e.g.
  UML XMI)
• common interchange formatfor all Metamodels!

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Vision of an MOF-based Integration of ITU
languages

• MOF based Metamodels for all languages
• standardized methodology and tool interfaces for
  language development
• Creation, Extension, ...
• merge of Metamodels possible
• Language integration (as UML is an integration of
  ...)
• definition of arbitrary notations ruled by the
  zeitgeist

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Can standards allow common tools for UML, SDL,
ASN.1, MSC, with backward compatibility ?
our visionary technology approach
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Questions, Statements ???