3. • A transformation tool takes a PIM and
transforms it into a PSM.
• A second (or the same) transformation tool
transforms the PSM to code.
• We have shown the transformation tool as a
black box. It takes one model as input and
produces a second model as its output.
4. • When we open up the transformation tool
and take a look inside, we can see what
elements are involved in performing the
transformation.
• Somewhere inside the tool there is a
definition that describes how a model should
be transformed.
5. • For example, define a transformation definition
from UML to C#, which describes which C#
should be generated for a (or any!) UML model.
• Transformation definition consists of a collection
of transformation rules (unambiguous).
• We can now define
transformation, transformation rule, and
transformation definition.
6. • A transformation is the automatic generation
of a target model from a source model,
according to a transformation definition.
• A transformation definition is a set of
transformation rules that together describe
how a model in the source language can be
transformed into a model in the target
language.
• A transformation rule is a description of how
one or more constructs in the source language
can be transformed into one or more
constructs in the target language.
7. METAMODELING
Introduction to Metamodeling Models, languages, metamodels,
and metalanguages
• We defined a model as a
description of (part of) a system
written in a well-defined
language.
• How do we define such a well-
defined language?
8. • Languages were often defined • However, BNF restricts us to
using a grammar in BNF. languages that are purely text
• For example, have a graphical based.
syntax, like UML. • We will need a different
mechanism for defining
languages in the MDA context.
• This mechanism is called
metamodeling.
9. Models, languages, metamodels,
and metalanguages
• A model defines what
elements can exist in a
system.
• The model of the language
describes the elements that
can be used in the
language.
10. • Because a metamodel is also a model, a metamodel itself must be written
in a well-defined language.
• This language is called a metalanguage.
• First, a metalanguage plays a different role than a modeling language in
the MDA framework, because it is a specialized language to describe
modeling languages.
• Secondly, the metamodel completely defines the language.
11. The Use of Metamodeling in the MDA
• First, we need a mechanism to define modeling languages, such that they
are unambiguously defined, a transformation tool can then read, write,
and understand the models. Within MDA we define languages through
metamodels.
• Secondly, the transformation rules that constitute a transformation
definition describe how a model in a source language can be transformed
into a model in a target language. These rules use the metamodels of the
source and target languages to define the transformations.
Notes de l'éditeur
we defined a model as a description of (part of) a system written in a well-defined language. A well-defined language was defined as a language which is suitable for automated interpretation by a computer.
If we define the class Cat in a model, we can have instances of Cat, (like "our neighbor's cat") in the system. A language also defines what elements can exist. It defines the elements that can be used in a model. For example, the UML language defines that we can use the concepts "Class," "State," "package," and so on, in a UML model. Looking at this similarity, we can describe a language by a model: the model of the language describes the elements that can be used in the language.
