Object-oriented Modelling of Communicating Gis-based Applications

Recent communication technologies (Internet, GSM, GPRS, PDA, GPS) have implied new GIS-based applications called telegeoprocessing applications [2]. This new type of systems concerns fields such as : · Internet access to geographic data using Web Map Server, · Mobile geographic databases, · Traffic monitoring. These new applications have naturally produced new needs in terms of conceptual methods. In order to facilitate the specification of telegeoprocessing applications, this paper proposes an extension of the Unified Modelling Language (UML) [4]. Indeed, UML began the new standard for the graphical object-oriented specifications of systems [4]. The works of [3] underline that UML extensions can be proposed in order to facilitate the GIS-based application design at a high level of abstraction. The purpose of these extensions is to encapsulate the complexity of geographic data during the first steps of modelling. This paper aimed at describing the method T-OMEGA for telegeoprocessing design. This method integrates: · a new extension of UML class diagrams for GIS-based application modelling (section 2), · an extension of the Object Constraint Language (OCL) associated to UML [4] so that topologic constraints can be expressed between geographical objects (section 3), · a new extension of UML for communication modelling ; this extension is intended for GIS designers with low skills in distributed systems field (section 4), · an implementation of proposed UML extensions (section 5). In introduction, the method T-OMEGA is evoked. This new method is dedicated to telegeoprocessing application design and was defined in the context of an industrial project with the French company CIRIL SA. The method T-OMEGA reuses some characteristics of the previous proposed method named OMEGA originally defined for GIS-based application design [3]. T-OMEGA considers two different types of actors participating to telegeoprocessing development project: GIS specialists and communicating system specialists. GIS specialists specify the global system to model and communicating system specialists define protocols of interaction modules used between applications. The methodology of T-OMEGA recommends that communicating system specialists use a dedicated language (such as SDL, ROOM, SADT, etc...) in order to design communication protocols. For GIS specialists, T-OMEGA proposes a specific UML extension that will be described in this paper.