An-Najah Staff

This thesis has been realized as a part of the project GOCD (French acronym for Management and optimization of document life cycle) and within the context of the French competitive cluster PICOM. The project aims to design and develop a new paperless workflow system and decision making tool to replace the current paper based system. The new workflow system must manage and optimize received credit demands at COFIDIS.The first part of this thesis presents and discusses a framework to model and implement workflow systems. The proposed framework allows more flexibility in workflow reengineering process and operational analysis for different business process. The proposed framework uses the most recent and promising language to model and execute workflow the Business Process Modeling Notation (BPMN) and Business Process Execution Language (BPEL).The flexibility offered by BPMN can also lead to undesirable properties for business process such as deadlocks and unreachablity. More, BPMN notation was designed to model business process, and little consideration was concentrated to represent data and resources. As a result, carrying out performance analysis on a BPMN model is also limited.To overcome these problems, we propose two additional phases in the reengineering process. They are applied to the target BPMN model. The first phase is verification and validation and the second one is optimization. These two phases are realized by transforming the BPMN model to a formal language, Petri nets. As for optimization, a new variant of bin packing problem has been defined. And we propose to integrate its resolution in a decision making tool.

Communication protocols are often investigated using simulation. This paper presents a performance study of the distributed coordination function of 802.11 networks. Firstly, our study illustrates the different classes of Petri Nets used for modeling network protocols and their robustness in modeling based on formal methods. Next we propose a detailed 802.11b model based on Object-oriented Petri Nets that precises backoff  procedure and time synchronization. Then, performance analyses are evaluated by simulation for a dense wireless network and compared with other measurements approaches. Our main goal is to propose a modular model that will enable to evaluate the impact of network performances on the performances of distributed discrete event systems.

The evaluation of using distributed systems DS in place of centralized systems has introduced the distribution of many services and applications over the network. However, this distribution has produced some problems such as the impacts of underlying networking protocols over the distributed applications and the control of the resources. In this paper we are interested particularly in manufacturing systems. Manufacturing systems are a class of distributed discrete event systems. These systems use the local industrial network to control the system. Several approaches are proposed to model such systems. However, most of these approaches are centralized models that do not take into account the underlying network. In this context, we propose the modeling of the distributed services and the underlying protocols with High-Level Petri Nets. Since the model is large, complex and therefore difficult to modify, we propose a component-based modeling approach. This approach allows the reuse of ready-to-use components in new models, which reduces the cost of development. To illustrate our approach and its reuse capabilities, we will implement it to model the link layer protocols of the norms IEEE 802.11b and IEEE802.3.