Model Driven Service Oriented Systems

Introduction Nowdays research and market pay attention to new software architectures like service oriented ones (SOA). These paradigms are intrinsically distributed systems, many times they are composed of federations of systems non controlled by the same organization. This often implies heterogeneous architec-tures and a not standardized semantic of communications and operations. More specifically, service-centric systems are dynamic loosely coupled infras-tructures, services are bound together only specifying communication protocols and interfaces expressed using common languages. The bindings are not hard coded in the systems, instead are created at runtime with the help of service brokers. These features permit to identify a basic pattern we can find in every service oriented architecture: there is a service provider which provides a service; there is a service broker which advertises services (service providers register new services onto the broker); there is a service consumer which interrogates the service broker to find needed services, makes the binding with these services at runtime and uses the service. Being architecturally different from conventional object oriented systems, these new architectures need new methodologies for analysis and design and also new development processes. Service oriented analysis and design methodologies must allow the design of a system at a higher abstraction level than object oriented analysis and design [41]. We deal with components which incapsulate complex functionality (like a cooperation of other services), and the system is heterogeneous. Object oriented analysis and design techniques also do not contemplate the level of dynamism reached by service oriented systems. These new design issues do not imply that we are supposed to forget object oriented analysis and design techniques. Basic principles, like separation of concerns and inheritance, are still valid and designing a service oriented ar-3 CHAPTER 1. INTRODUCTION chitecture also means designing the internals of services. This last issue is not different from designing a traditional object oriented system, which can be built with traditional OOAD techniques. In the last few years a new development approach (MDA) has been designed. It is is mainly concerned with traditional object oriented systems but not necessarily restricted to them. The main feature of this new methodology is to allow the developer of an application to work at a higher abstraction level making heavy use of models. Developers can concentrate on a platform independent description of the system without bothering about lower level details. MDA is already supported by many commercial tools, and most of its …