Web services are changing software development thanks to their loosely coupled nature and simple adoption. They can be easily composed to create new more powerful services, allowing for large programming systems. Verification and validation techniques try to find defects in a program to minimize losses that its malfunction could cause. Although many different approaches have been developed for “traditional” program testing, none of them have proven definitive. The problem is even more challenging for new paradigms like web services and web service compositions, because of their dynamic nature and uncommon web service-specific instructions. This chapter surveys the different approaches to web service and web service composition verification and validation, paying special attention to automation. When no tools are available for a given technique, academic efforts are discussed, and challenges are presented.
TopIntroduction
According to the Software Engineering Body of Knowledge - SWEBOK (Abran & Moore, 2004),
verification and validation addresses software product quality directly and uses testing techniques which can locate defects so that they can be addressed.
Software Verification and Validation (V&V) has been a key problem in Computer Science since the so-called Software Crisis, causing monetary and human losses (Leveson, 1995). Many efforts have been made since then to develop computer programs that meet system requirements, but up to date, no solution has proven definitive (Myers, Badgett, Thomas, & Sandler, 2004). This way, a “good” quality can only be achieved by carefully combining different techniques.
Service Oriented Architectures (SOA), and Web Services (WS) are changing software development. They greatly ease system interoperability, and new WS can be built on them using service composition technologies. But they also include some peculiarities uncommon in other paradigms (like WS-specific instructions), so V&V techniques have to be adapted accordingly (Bozkurt, Harman, & Hassoun, 2010). This chapter surveys the different approaches to web service and web service composition V&V, paying special attention to the tools available to automate them.
The rest of the chapter is divided into five sections. The first one provides some background information to make the text self-contained. The second section, Service Verification and Validation, deals with V&V techniques for external WS, given that we don't have access to their code (i.e. black-box testing). The following one explains additional techniques to test the internal logic of a composition of different WS, that is white-box testing. Along these two sections we comment tools1 to automate the different software testing techniques, or proposals showing how to implement them. In the fourth and fifth sections, we compile future research directions, and draw some conclusions about the state of the art of service and service composition V&V. Finally, we include the references, some additional readings and a glossary of key terms and definitions.