Information AboutQvt |
| CATEGORIES ABOUT QVT | |
| software engineering | |
| systems engineering | |
| unified modeling language | |
| domain-specific languages | |
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Abstract Of particular importance to Model Driven Engineering or Model Driven Architecture is the notion of Model Transformation . The OMG has defined a specific standard for model transformation called MOF/QVT or in short QVT . Several model transformation languages like VIATRA or ATL are presently available, with different level of compliance to the QVT standard. Description Model Transformation is the process of converting a model Ma conforming to metamodel MMa into a model Mb conforming to metamodel MMb. If MMa=MMb, then the transformation is endogeneous else it is an '''exogeneous''' transformation. Model transformation is a critical component of MDA. Recognizing this, an RFP (Request for proposal) has been issued by OMG on MOF Query/Views/Transformations to seek a standard compatible with the MDA recommendation suite (UML, MOF, OCL, etc.). Several replies were given by a number of companies and research institutions that evolved during three years to produce a common proposal that was submitted and approved. Presently there are several products (commercial or open source) that claim compliance to the QVT standard. QVT defines a standard way to transform source models into target models. There are several ideas in this proposal. One is that the source and target models may conform to arbitraries MOF metamodels. Another one is that the transformation program is considered itself as a model, and as a consequence also conforms to a MOF metamodel. This means more precisely that the abstract syntax of QVT should conform to a MOF 2.0 metamodel. As a matter of fact, this is a bit more complex. First the QVT language integrates the OCL 2.0 standard. Second QVT defines not one but three Domain Specific Languages named ''Relations'', ''Core'' and ''Operational Mappings'' and these languages are organized in a layered architecture. Relations and Core are declarative languages at two different levels of abstraction, with a normative mapping between them. The Relations language has a graphical concrete syntax. The QVT/OperationalMapping language is an imperative language that extends both QVT/Relations and QVT/Core. The syntax of the QVT/OperationalMappings language provides constructs commonly found in imperative languages (loops, conditions, etc.). Finally a mechanism called ''QVT/BlackBox'' for invoking transformation facilities expressed in other languages (''XSLT'', ''XQuery'') is also an important partof the specification. For the time being the QVT standard only addresses model to model transformations, model meaning some entity conforming to any MOF 2.0 metamodel. All transformations of type ''model to text'' or ''text to model'', whatever the text is (XML, Code, SQL, etc.), are presently outside the scope of QVT and possibly subject to other standardization initiatives. They may be viewed as alternative transformation DSLs in the MDA technical space. SEE ALSO Articles
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