Introduction
The aim of this project is to propose a new framework for the dynamic enforcement of composite Web services security, which is based on a synergy between Aspect-Oriented Programming (AOP) and BPEL (Business Process Execution Language). This synergy is achieved through the elaboration of a new language called AspectBPEL, which is used to specify security policies as separate components, referred to as aspects, to be weaved systematically in a BPEL process. Then, we identified some problems related to the complexity of XACML policies and performed experimental study in this regard. Afterwards, we extended the work with model-driven approach to address context-aware requirements and developed an Eclipse plugin for AspectBPEL and integrated it in the BPEL project. Finally, we addressed many concerns related to the efficiency of real-time decision process (i.e. policy evaluation) and the correctness of complex policies. In this regard, we proposed a novel set-based scheme that provides efficient evaluation and analysis of XACML policies. Our approach constitutes of elaborating (1) set-based language that covers all the XACML components and establish an intermediate layer to which policies are automatically converted, (2) policy evaluation module that provides better performance compared to the industrial standard Sun Policy Decision Point (PDP) and its corresponding ameliorations, and (3) policy analysis module that allows to detect flaws, conflicts and redundancies in XACML policies.