Model-Driven Software Development by Thomas Stahl

Author:Thomas Stahl
Language: eng
Format: mobi, epub
ISBN: 9781118725764
Publisher: John Wiley & Sons
Published: 2013-06-24T16:00:00+00:00

10.4 An Example Transformation

In Section 6.11 we discussed the ALMA metamodel example, which can be used to model astronomic observational data. It provides a platform-independent abstraction over all the possible artifacts required for the ALMA software infrastructure. One possible platform-specific incarnation of ALMA data could be a relational database. In this section, we discuss a transformation from the ALMA metamodel to a simple relational database metamodel, referred to as DB.

Before discussing the actual transformation, we have to specify the input (or source) and output (or target) metamodels of the QVT transformation accurately. Since QVT assumes MOF-based metamodels for its input and output, we show a MOF rendition of the ALMA metamodel. Note that it is in theory possible to specify a QVT transformation directly on the UML profile, where the source metamodel would then have to be UML itself. However, because the UML metamodel as an instance of MOF is extremely large and complex, such transformations are often difficult to understand, let alone write. The QVT transformation writer is then required to understand the UML metamodel as an instance of MOF, which may not be straightforward and, more importantly, may distract from the domain-specific intentions of the metamodel.

A UML Profile is in many ways a concrete syntax model. From practical experience, we have observed that well-structured and adaptable transformations3 written directly against a UML profile tend to first transform the profile into an implicit MOF-like metamodel before implementing the actual transformation logic. This is particularly important when the transformation is the basis for reuse and adaptation4.

Figure 10.2 shows the ALMA metamodel as an instance of MOF.

Figure 10.2 ALMA metamodel as an instance of MOF.

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