Meta l metacase tools & possibilities

MetaL MetaCASE Tools &
Possibilities

Fahad Rafique Golra

19/03/2012 Département Informatique

Table of Contents

1. MetaL1
2. MetaL2
3. Examples
4. Benefits
5. Discussion
page 1 Département Informatique Fahad R. Golra

MetaL Language

 Two distinct layers

• MetaL 1 (minimal kernel language)
• MetaL 2 (formal foundation)


MetaL 1 Repository

 Everything in the repository is a dataobject (D: set
of all dataobjects)
 Facets of Dataobject
• Object (O: set of all objects)
• Properties (P: set of all properties)
domain : P  O
range : P  O
« facet of » defines the hidden dataobject
fo : O  P  D
A dataobject can be a property, an object or both


Properties & Objects

o1, o2 , o3 , op O

op, q P

 op has both a property and an object facet


Dataobject Types

 The objet type, OT is a subset of O
 The property type, PT is a subset of P
 Instance-type relationship is modeled as

o def
typeo O OT x y typeo x, y
typep P PT p def
x y type p x, y

A property has exactly one property type
 Every object has atleast one object type


Types

 Thedomain (resp. range) of a property must be an
instance of the domain (resp. range) of its property
type.

o
domain( p)  domain( pt )

and
o
range( p)  range( pt )


Object values

 Object values are specialized objects that hold
value
val : OB  OS  O  O  O  B  S      

 If x OT then val ( x) T where T denotes any
type N,B, …

 The object value sets are disjoint and are all
included in O.


Inheritance & Name

 isa relationship isa OT OT

 Objecttypes inherit properties from their
supertypes
typeo (o, t ) t isa* t typeo (o, t )

 Object and property types have unique names
x, y OT : name( x) name( y) x y

p1 , p2 P : name( p1 ) name( p2 )
T
Fam* (domain( p1 )) Fam* (domain( p2 )) p1 p2


MetaL1 Specification

 Root object type ( ) and property type ( )

( ) is an instance of root object type and
supertype of the elementary types

 For example:
TN OT  ON isa(TN , )
typeo (TN , ) typeo (TN , TN )
val (TN ) 0 name(TN ) int


Elementry Types

 Each object value is typed by exactly two types

o ON : typeo (o, TN ) typeo (o, ) 2


Example

 To model: Albert and Bernard are two persons
who have the same age, they are 45 years old.


Integrity

 If some object o O is deleted
- If p P is a property whose domain( p) o typep ( p, pt ) true for some
pt P and if dr kind ( pt ) then range( p) must also be deleted.
T

- If p P is a property whose range( p) o typep ( p, pt ) true for some
pt P and if rd kind ( p ) then domain( p) must also be deleted.
T t

 If some property p P is deleted
- If pd kind ( pt ) , then domain( p) must be deleted

- If pr kind ( pt ) , then range( p) must be deleted


MetaL 2 Metametamodel

 CommonMetaObject

- Default supertype of all other metaclasses
 CommonMetaModel

- Default supertype of all constructs denoting metamodels

- Inherits from CommonMetaObject
 MetaObject

- Key metaclass as main concept

- Generalizes MetaRole, MetaProperty, MetaModel

- Has a unique name



 MetaProperty

- Adds slots to metaobjects

- Inherits from MetaObject

- Domain of cardP property which limits the number of concrete
properties

- Cardinality -1 is considered infinite, otherwise ≥ 1

- Must have exactly one cardinality and one type

- Cardinality is the range of exactly one metaproperty



 MetaRole

- Both object type and property type

- As object type, subtype of MetaObject

- As property type, has MetaObject object type as domain and
range

- Domain of cardR property, where cardR denotes one-to-
one(0), one-to-many(1), many-to-one(4), many-to-many(5),
manys-to-manys(10).

- Cardinality is the range of exactly one metarole



 MetaModel

- Aggregate concept defined by a set of metaobjects

- Inherits from CommonMetaModel

- PartWhole metaRole has CommonMetaObject as domain
and CommonMetaModel as range.

- PartWhole is domain of
– nickname:optional, unicity of name inside a metamodel
– canNotBeShared: allows sharing in metamodels
– isNotDependentOn: dependency of object on metamodel
– isHidden: hiding technical details


Example

 PartWhole

- metametamodel – metaclass

- statechart – state

- coffemachine - IDLE



 Inheritence

- MetaObjects can inherit from other MetaObjects

- Multiple inheritance is allowed

- Cycles are forbidden in the generalization graph

- Inheritance between metamodels is allowed

MM typeo ( , MetaModel)


MetaL 2 Concrete Layer

 ConcreteObjects

- Instance of metaobject which is instance of MetaObject

- Can belong to several concrete models

- Can not live outside the definition of atleast one concrete
model
 Concrete Property
- Valued slot attached to concrete object

- Can be shared by multiple concrete objects

- As its a metaobject so it can own properties, roles etc


MetaL 2 Concrete Layer

 Concrete Roles
- Has property and object facets

- Links two objects and can be a domain/range of property

- Respects cardinality

 Concrete Models
- Instance of metamodel which is an instance of MetaModel

- Composed of concrete objects that are instance of
metaobjects in metamodel definition.


Example Coffee Machine (state chart)
Redundancy
Properties can have
properties then MetaRoles
are redundant

Instance of/Conforms to
« state name » a property
or an object


General Benefits

- Meta(models) can overlap

- Sharing between (meta)models is fine-grained: (meta)objects,
(meta)models, …

- Multiple instantiation

- Free from instance/type delimitation in modeling layers

- Granularity: meta(models) are meta(objects)

- Metamodel refinement: As metamodels can be extended
further and refined.


Example


Points for discussion

• Having shared objects can help transformations, as
some part of the (meta)model remains constant in
transformation

• Maintaining metamodel families by transformations
without referential redundancies

• As other terminal languages can be defined on top
MetaL1, so a complete family of of DSLs can exist
e.g. for Component Oriented Programming.


References

1. V. Englebert. MetaL1: a formal specification. Technical Report,
University of Namur – PRECISE Research Centre, Belgique,
May 2010.

2. V. Englebert. MetaL2: a formal specification. Technical Report,
University of Namur – PRECISE Research Centre, Belgique,
May 2010.

3. V. Englebert, P. Heymans, “Towards More Extensive
MetaCASE Tools”, In: Proceedings of CAiSE 2007, Springer-
Verlag Berlin Heidelberg, pp 454–468, 2007.


Meta l metacase tools & possibilities

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