Agility

Software applications are seldom built for the sort of general purpose uses that a computer is suitable for. Despite our ingenuity in building computer chips that can run everything from aircraft to video games, the software itself is good for only one kind of activity or another. The result is that all too often software that is anything but “soft” – it is very brittle and difficult to change.

In chapter8, we emphasized that an SOA addresses this long-standing problem by treating software quality – and in particular agility – as an integral part of software architecture. It is important to note that this does not mean formalizing the development process, as in the “engineering” approach to software quality, exemplified by the CMMI, the established approach to formalizing the processes of creating and managing software.

The fact is that when we build software to meet specific, predefined requirements, it almost always falls short of meeting the true requirements for that software, primarily because the actual requirements for software are typically in a state of constant flux. Software must be agile enough to meet as yet undefined requirements at some point in the future.

In this chapter, we therefore focus on how to design agile services. This takes us to the heart of SOA: modeling techniques that help get the right set of services.