Process Process

Modeling and Analysis Alexandre David November 18, 1998 Introduction It is our experience with model-checkers such asUppaal [1] that a large part of the total time, in most of the case studies, is spent on constructing the system model. This has lead to a strong demand for a modeling language with features supporting abstractions such as hierarchical descriptions of models. There have been several such modeling languages as Statecharts [3], developed particularly for modeling and simulation. However they did not o er the facilities of Object Oriented modeling. Furthermore, rather little work has been done on static analysis for such languages using information such as types, hierarchical structures etc, to guide veri cation. We present the object{oriented modeling language UL++ for the tool Uppaal in order to build a foundation for future work in this direction. The rest of this paper is organized as follows : section one gives the principles of object modeling, section two the informal syntax of UL++, section three the semantics and section four the translation to Uppaal in order to simulate and verify a model. 1 Object Modeling 1.1 Motivation Uppaal models are based on timed automata extended with variables. These automata are based on processes which have clocks to simulate time and which synchronize with each other on channels. Figure 1 gives an example of two processes synchronizing on a channel. The transitions are decorated with clock resets here. e-mail : [email protected]. This work was carried out as my Msc project at Department of Computer Systems, Uppsala University Box 325, S-751 05 Uppsala, Sweden. c! c? x:=0 P1 P2