UML, being the industry standard as a common OO modeling language, needs a welldefined semantic base for its notation. Formalization of the graphical notation enables automated processing and analysis tasks. This paper describes a methodology for synthesis of a Petri net model from UML diagrams. The approach is based on deriving Object Net Models from UML statechart diagrams and connecting these object models based on UML collaboration diagram information. The resulting system-level Petri net model can be used as a foundation for formal Petri net analysis and simulation techniques. The methodology is illustrated on some small examples and a larger case study. The case study reveals some unexpected invalid system-state situations. Int. J. Soft. Eng. Knowl. Eng. 2001.11:643-673. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/05/15. For personal use only. 644 J. A. Saldhana, S. M. Shatz & Z. Huization of ordinary PNs, allowing convenient definition and manipulation of data values. CPNs also have a formal, mathematical representation with a well-defined syntax and semantics.We suggest that design knowledge can be captured and formalized by the methodology outlined in Fig. 1. The methodology can enable a UML designer to verify UML models. In this paper, we focus on the key step of deriving an Object Petri net (OPN) from UML diagrams. We start with UML models as created by a system designer (appropriate UML editors can be used to develop UML statechart and collaboration diagrams). In our methodology, statechart diagrams are first converted to flat state machines. These state machines are then converted to a form of OPN called Object Net Models (discussed in Sec. 3). Then the UML collaboration diagrams are used to connect these object models to derive a single CPN for the system under study. Any standard CPN analyzer can be used to support analysis and simulation of the resulting CPN. This framework has the advantage of exploiting the mature theory and tools for Petri nets and essentially hiding these details from the end-user.

UML statecharts are used for describing dynamic aspects of system behavior. The work presented here extends a general Petri net-based methodology to support formal modeling of UML statecharts. The approach focuses on the specific task of generating explicit transition models associated with the hierarchical structure of statechart. We introduce a state-transition notation to serve as an intermediate model for conversion of UML statecharts, and in particular, the complexity of composite states, to other target specifications. By defining a process for deriving, from UML statecharts, a statetransition notation that can serve as an intermediate state machine model, we seek to deepen understanding of modeling practices and help bridge the gap between model development and model analysis. This work covers all of the primary issues associated with the hierarchical structure of composite states, including entry and exit transitions, transition priorities, history states, and event dispatching. Thus, the results provide an important step forward toward the goal of modeling increasingly complex semantics of UML statecharts.Keywords: Composite States, Petri Nets, Statecharts, State-transition Notation, UML IntroductionThe Object Management Group (OMG) adopted a new paradigm for software development called Model Driven Architecture (MDA) [Poo01] to recognize the fact that models are important artifacts of software development and they serve as a basis for systems as they evolve from requirements through implementation. In MDA, models are defined in the Unified Modeling Language (UML), which is a graphical language for visualizing, specifying, constructing, and documenting a software-intensive system [BJR99]. MDA raises the importance of addressing many primary issues in the current standard of UML.One of the issues, the semantics of UML, is the subject of active discussion and much research activity [Rum98]. UML is a semi-formal language, since some parts of it are specified formally, while other parts, 1 This material is based upon work supported by the U.S. Army Research Office under grant number DAAD19-01-1-1-0672, and the U.S. National Science Foundation under grant number CCR-9988168.2 for instance dynamic semantics, are defined informally [OMG01]. The lack of formal dynamic semantics for this language limits its capability for analyzing defined specifications. The need for a formal semantics for UML is motivated in the literature [BL+00,FE+98], and the pUML (precise UML) group has been created to achieve this goal [PUML]. A number of projects discuss formalizing UML by mapping the UML notation to an alternative notation to give the UML notation a precise semantics and achieve UML verification. This paper is concerned with one core component of UML -statechart diagrams [OMG03].Statechart diagrams are used for describing dynamic aspects of system behavior in the framework of UML. states, and event dispatching. This work defines an important step forward toward the goal of modeling increasingly complex seman...

We present a comprehensive unified modeling language (UML) statechart diagram analysis framework. This framework allows one to progressively perform different analysis operations to analyze UML statechart diagrams at different levels of model complexity. The analysis operations supported by the framework are based on analyzing Petri net models converted from UML statechart diagrams using a previously proposed transformation approach. After introducing the general framework, the paper emphasizes two simulation-based analysis operations from the framework: direct MSC inspection, which provides a visual representation of system behavior described by statechart diagrams; and a pattern-based trace query technique, which can be used to define and query system properties. Two case-study examples are presented with different emphasis. The gas station example is a simple multi-object system used to demonstrate both the visual and query-based analysis operations. The early warning system example uses only one object, but features composite states and includes analysis specifically aimed at one composite state feature, history states.