English abstract
A Web service is a software system designed to support inter-operable machine-to machine interaction over the Internet. The Web services underlying technologies and standards allow interfacing, publishing, and binding services available on the Web and accessible through open Internet protocols such as HTTP, FTP, SMTP, etc. Moreover, Web services can easily live with distributed object computing middleware such as CORBA, DCOM and EJB, and integrated with semantic Web to overcome their limitations. These capabilities make Web services technology a natural platform to implement the service-oriented architecture (SOA), which is a methodology for achieving application interoperability and reuse of IT assets Yet, Web services deployment is still hindered by technical as well as methodological issues. The technical issues are related to security, policy, transactions management, orchestration, and quality of service (QoS). The methodological issues concern with approaches, architectures, methods, models, and tools used to deploy Web services. This project deals with the approaches and tools to: identify, analyze, design, implement and deploy Web services as an instance of SOA. To achieve the objectives of this project, the following points were created: 1. A study of SOA methodology and Web services underlying technologies. 2. A comparative study of different approaches for deploying Web services, namely business-oriented and IT-oriented, according to criteria specified with respect to Web service development properties such as: (i) their categorization including granularity, accessibility, complexity and functionality, (ii) the building blocks on top of which they are built, (iii) the development process, and (iv) how to deal with legacy systems. These studies result in a comprehensive multi-abstraction level architecture with respect to a business model, where higher abstract levels deal with business orientation, and the lower levels concern with IT. The methodology includes a five step design process assisted by a case tool, which consists of Step 1: Specification of the SOA requirements Step 2: Identification and Analysis of Web services Step 3: Design of Web services Step 4: Implementation of Web services Step 5: Deployment of Web services A CASE tool that assists the design process, namely the identification, the design and the implementation steps has been specified and implemented. For lower steps, the available market technologies such as IBM WebSphere, SUN J2EE, or TME GLUE can be used. To bring the legacy system in a Web services fom, a legacy wrapper/adapter is used.
