الملخص الإنجليزي
Web services are rapidly becoming the de facto standard realization of the Service Oriented Architecture (SOA) due to: (i) the machine-readable standard format (XML) of their functional and non-functional specifications, and (ii) their messaging protocols which can be built on top of the Internet protocols. However their development with respect to SOA requires a methodology including a development life cycle. This development methodology needs to consider the legacy applications for several reasons including: (1) SOA is based on composing new solutions from existing loosely coupled services rather than building them from scratch, (2) legacy applications have most of the business functions locked inside of them, and (3) legacy applications constitute an important asset for the enterprise that should be modernized and preserved as investments.
There exist numerous automated tools to wrap legacy applications and expose them as Web services. Generally these tools consist of simply placing a thin layer of SOAP/WSDL/UDDI on top of legacy applications. While these tools have several features to wrap different parts of the legacy application (data, logic, or interface), they do not provide a proper guidance on which feature is most suitable for the target legacy application with respect to its accessibility (transaction, data or session based access).
This project mainly aims at defining an approach to wrap any legacy application with respect to its accessibility and expose it as a Web service regardless of the wrapping tool in use. It consists of an exploration and a survey of respectively several projects and automated wrapping tools concerned with wrapping and exposing legacy applications as Web services. This exploration has resulted in a categorization of the wrapping techniques into three basic categories: Transaction, Data, and Session Based Techniques. This categorization has guided an approach to wrap legacy applications as Web services. The proposed approach consists of four phases: (P1) identification and analysis of the legacy application, (P2) extraction of the business rules from the legacy application, (P3) selection of the suitable wrapping technique, and (P4) design and deployment of a Web service. The approach is illustrated through a student information system as a validation case study.
