Today, many Web-based products and software systems must continuously evolve in E-Time. Nonetheless, they must be easily changeable, extensible, and reveal many other non-functional properties. The question arises how software systems can be prepared to cope with these requirements? Conventional applications are driven by a specific set of requirements that is stable during development, at least in theory. Applications may be extended after their rollout, but their usage context is mostly unchanged. This approach doesn´t work anymore for a Web-based world. Here, new applications must be developed with change and integration in mind. This requires a more framework-like approach where the same applications may participate in different contexts.
To support this kind of flexibility, we need to increase entropy. That means, applications shouldn´t make too many assumptions a priori where they run and how they interact. Everything should be loosely coupled. Meta-information should be decentralized. For this purpose, applications need to resort to standards and minimize dependencies on other applications. This does not only hold for inter-application interaction, but also for intra-application boundaries. Thus, we should partition applications into decoupled services we can compose to completely new applications previously not anticipated.
In other words: we need agile software technologies for an agile world. What we finally get is a world of services that interoperate and interact with each other using Web-based standards. Finally, we have reached the universe of Web Services and Web-based middleware. '