Interacting Abstract State Machines.
Marcelo de Almeida Maia, Vladimir O. Di Iorio, Roberto S. Bigonha · 1998
InteractingAbstractStateMachinesMarcelo de Almeida Maia1, Vladimir Oliveira Di Iorio2, and Rob erto da SilvaBigonha31Universidade Federal de Ouro Preto, Brazil, [email protected] Federal de Vicosa, Brazil, [email protected] Federal de Minas Gerais, Brazil, [email protected] this work we prop ose an extension to the original mo del ofAbstract State Machines. We fo cus on the mo dularization supp ort andontheexplicitinteractionabstractionbetweenmo dules(unitsofsp eci cation). We provide the new language syntax and semantics, andalso the sp eci cation of the Alternating Bit Proto col using the prop osedmetho d.1Intro ductionMuchoftheworkb eingdoneinsoftareengineeringareaconcernsdevelopmentofmechanisms that facilitatethe reuse and exibilityof softwarecomp onents.Themostpowerful resource toachieve thesegoals ismo dularity,which is based up on abstraction and information hiding and it is the only e ec-tiveway to break down the complexity of large systems. Even though AbstractState Machines[4] supp ort abstraction and information hiding, we advo cate morepowerfulabstractionmechanisms.Ifeconsidertheinherentmetho dologyofpro ducingASMssp eci cationsasametho dologythatprovidesverticalab-straction mechanism, in the sense that the ground mo del is successively re neduntil considered adequate, it is reasonable to think that it do es lack some kindof horizontal abstraction to supp ort the reuse of existent sp eci cations. An ar-gument to supp ort this view can b e found in [8], where are de ned some desiredcharacteristicsforgoodmo dularizationmechanismssuchasmo dularcomp os-ability, mo dular decomp osabilit, mo dular understandabilit, mo dular continu-ityand mo dular protection. Considering these characteristics, a central themethat a ects directly each one of them is the sp eci cation of how software mo dulesinteract with each other. So, our decision is in the direction of a formalism thatexplicitly enables the software engineer to write down how the interaction o ccursbetween the mo dules. We adopt a message exchanging style b ecause we b elieveitprovides a natural abstraction of how ob jects interact in the real world. When weexplicitly sp ecify the interaction b etween mo dules, we are automatically inclinedto think ab out the concurrency issues involved in the interaction pro cess. In ourview, mo dularization and concurrency concepts are interdep endent and shouldnot b e addressed separately, and this has inuenced our decision of putting themtogether in a unique framework.