MDA

Content

• MDA framework – Transformation

• Meta-model – Meta-language

• 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.

• 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.

• 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.

• 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.

METAMODELINGIntroduction to Metamodeling

• 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?

Models, languages, metamodels, and metalanguages

• Languages were often defined using a grammar in BNF.

• For example, have a graphical syntax, like UML.

• However, BNF restricts us to languages that are purely text based.

• We will need a different mechanism for defining languages in the MDA context.

• This mechanism is called metamodeling.

• 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.

Models, languages, metamodels, and metalanguages

• 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.

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.