reverse engineering – recent advances and applications - OpenLibra

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Reverse Engineering – Recent Advances and Applications
NEREUS is an intermediate notation open to many other formal languages such as
algebraic, logic or functional. We define its semantics by giving a precise formal meaning to
each of the constructs of the NEREUS language in terms of the CASL language (Bidoit &
Mosses, 2004).
3.2 Transforming metamodels into NEREUS
We define a bridge between EMOF- and Ecore- metamodels and NEREUS. The NEREUS
specification is completed gradually. First, the signature and some axioms of classes are
obtained by instantiating reusable schemes. Associations are transformed by using a
reusable component ASSOCIATION. Next, OCL specifications are transformed using a set
of transformation rules and a specification that reflects all the information of MOF
metamodels is constructed.
The OCL basic types are associated with NEREUS basic types with the same name. NEREUS
provides classes for collection type hierarchies. The types Set, Ordered Set, Bag and
Sequence are subtypes of Collection.
The transformation process of OCL specifications to NEREUS is supported by a system of
transformation rules. By analyzing OCL specifications we can derive axioms that will be
included in the NEREUS specifications. Preconditions written in OCL are used to generate
preconditions in NEREUS. Postconditions and invariants allow us to generate axioms in
NEREUS. We define a system of transformation rules that only considers expressions based
on Essential OCL (OCL, 2010). The following metaclasses defined in complete OCL are not
part of the EssentialOCL: MessageType, StateExp, ElementType, AssociationClassCallExp,
MessageExp, and UnspecifiedValueExp. Any well-formed rules defined for these classes are
consequently not part of the definition of the transformation rule system.
The system includes a small set with around fifty rules. It was built by means of an iterative
approach through successive refinements. The set of rules was validated by analyzing the
different OCL expression attached to the UML metamodels, MOF and QVT.
As an example we show a few rules of the system. A detailed description of the system may
be found at (Favre, 2010). In each rule the shaded text denotes an OCL expression that can
be translated by the non-shaded text in NEREUS:
Rule OCL
NEREUS
R1 v. operation(parameters)
operation(TranslateNEREUS(v),TranslateNEREUS (parameters))
R2 v->operation (parameters)
operation(TranslateNEREUS(v),TranslateNEREUS (parameters))
R3 v.attribute
attribute (v)
R4 context Assoc
object.rolename
Let a:Assoc
get_rolename (a, object)