GUERRERO, D. D. S.; http://lattes.cnpq.br/2050632960242405; GUERRERO , Dalton Dario Serey.
Abstract:
This thesis discusses the integration of object oriented concepts and Petri nets modelling
of systems. In particular, distributed and concurrent software systems. We argue that the
main cause for the unsuccessful object oriented Petri nets notations is the approach used
to combine concepts which emphasizes syntactical aspects instead of the semantic ones.
We defend that semantic integration principles must guide the combination of syntactical
structures in an orthogonal way. This approach promotes the development of notations
that are more easily accepted by designers, since i t minimizes the influence the paradigms
have on each other. The essence of each language is better preserved this way. Also, it
maximizes the chances of adapting the existing analysis techniques, because most of them
depend on semantical aspects.
Present notations combine concepts in a syntactical way. Such approach does not provide
two complementary, articulated views of the models. Instead, it provides a single
statically compound view. One of the main reasons is the unbalanced integration of concepts.
Because object orientation is often explained informally, formalizations are clearly
Petri-net biased. This has two consequences. First, it forces different interpretation for
existing concepts of Petri nets, so they can be adapted to object language. This has a severe
impact on the chances of adaptation of existing techniques, because they rely heavily
on concepts whose interpretations are modified. Second, it forces the adaptation of object
concepts, so they fit well within Petri nets. This leads to a loose/weak characterization of
the object paradigm and, as a consequence, to a badly accepted notation.
As a result, we present an integration strategy that avoids the problems mentioned
above. The strategy consists on balancing the emphasis and the role that each paradigm
has on the proposed notation, assuring that the notation and its meaning are defined
in a orthogonal way, and defining a semantic composition of the involved concepts. In
practice, this was achieved through the explicit adoption of a conceptual computing model
for concurrent and distributed systems for which the central notion is the object. We also
present a (Petri net independent) formalism that allows the modelling of the evolution of
concurrent object systems. Finally, we propose an integrated notation, which is based on
meaning composition instead of syntactical integration.