When Parameterized Model Driven Development Supports Aspect Based SOA

Introduction

Economical context impacts companies and their Information Systems (IS). Companies acquire new competitors or develop new business skills, delocalize completely, or parts of their organization. Moreover they are faced with powerful competitors, and they continuously have to develop new products that fit to customer needs, sometimes in as little as 3 months. There, IS is thus regularly confronted with these complex evolutions and should overcome these changes. With Service Oriented Architecture, each application owns a set of interfaces, offering services and masking implementation details. Applications can thus be seen as independent black boxes connected to a middleware such as an Enterprise Application Integration bus (EAI). However, this integration solution does not allow the interconnection of heterogeneous applications or infrastructures, such as for example distant IS. Web services are the cheapest and simplest technical solution to solve this problem. Since they are based on standards such as XML (eXtensible Markup Language), web services offer interoperability and allow loose coupling. However, we noticed several limitations concerning web services as a very monolithic code encapsulating a variety of different concerns such as business, security or confidentiality. Moreover, it is sometimes required to change a Web service’s code according to new needs, and thus having to redeploy the Web service. Each change is time consuming and during that time, the web service is not available. Nowadays, flexibility to changes is thus not optimal in web services. We have proposed aspect based solutions to gain in code simplicity without having to re-deploy the code and in a “non-intrusive” manner (Hmida, 2006; Tomaz, 2006). We have based our latest approach on extended BPEL (Business Process Execution Language) (Andrews, 2003) and temporized automatons (Alur, 1994; Haddad, 2006), that we prototyped by providing client, and server adaptability. Nevertheless, we are convinced this pragmatic and efficient solution is too complex for non expert users and developers and is difficult to maintain, because it requires strong technical knowledge.

Recently, we have investigated a model driven approach and context awareness to provide developers with the mechanisms that allow them to represent an application in an abstract way (in a model) and then, to automatically generate the corresponding code. We aimed to explore adaptability and flexibility on a service platform using context with the benefits of an MDD (Model Driven Development) strategy (OMG, 2001). These benefits are related to productivity, quality, adaptability and maintenance. We propose to discuss about the relevance of merging these two solutions.

We explain our technical approach based on services and aspects to implement adaptability in SOA and BPEL. Next we show how our first researches on the MDD approach ensure service adaptability while using context mechanisms. We comment on the needs of merging and extending these two research works: aspect based services for SOA and context modeling with parameterized transformation. It launches our future researches in this topic.