Model-Driven Engineering - Model-Driven and Software Product Line Engineering - page 85

syntax of QVT such as SmartQVT [FRA 09], at the time of
writing, there is no official reference implementation.
There are several implemented MOF-based model-
to-model transformation languages,such asATL [JOU 06] and
Kermeta[MUL05].Similarly,theopenArchitectureWare(oAW)
framework [OAW 09] provides a textual language to support
the activities of model-to-model transformations, the Xtend
language, but also a language to support the activities of code
generation, the Xpand language.
3.6.1. QVT
Recognizing that model transformations are a critical
component of MDE, OMG issued a request for proposal (RFP)
in 2002 on MOF Query/View/Transformation. It was finally
adoptedinJuly2007.QVTdefinesastandardwaytotransform
source models into target models. In QVT, source and target
models may conform to arbitrary MOF metamodels. The
transformation program is itself considered a model; then, it
conforms to a MOF metamodel. This means that the abstract
syntax of QVT should conform to a MOF 2.0 metamodel.
The QVT standard only addresses model-to-model
transformations. Transformations of type model-to-text
or text-to-model, are currently outside the scope of QVT.
QVT has a hybrid declarative/imperative nature and it
defines three domain-specific languages named Relations ,
Core and Operational Mappings . Relations is a declarative
language, which has a graphical concrete syntax and supports
complex object pattern matching and object template creation.
Relations supports traces between model elements involved
in a transformation (they are created implicitly). Core is a
declarative language that supports pattern matching over
a flat set of variables by evaluating conditions over those
variables against a set of models. In Core, all trace classes are