Software must be adapted to accommodate new features in the context of changing requirements. In this paper, we illustrate how applications with aspect weaving capabilities can be easily and dynamically adapted with unforseen features. Aspects were used at three levels: in the context of semantic analysers, within a BPEL engine that orchestrates Web Services, and finally within BPEL processes themselves. Each level uses its own tailored domain-specific aspect language that is easier to manipulate than a general-purpose one (close to the programming language) and the pointcuts are independent from the implementation.

Web service orchestration engines need to be more open to enable the addition of new features into service-based applications. In this paper, we illustrate how, in a BPEL engine with aspect-weaving capabilities, a process-driven application based on the Google Web service can be dynamically adapted with new features and hot-fixed to meet unforeseen post-deployment requirements. Business processes (the application skeletons) can be enriched with additional features such as debugging, execution monitoring, or an application-specific GUI. Dynamic aspects are also used on the processes themselves to tackle the problem of hot-fixes to long running processes. In this manner, composing a Web service 'on-the-fly' means weaving its choreography interface into the business process.