We are assisting to a paradigmatic shift in
developing Web applications since their componentsare often distributed and
deployed as services among different organizations. Their logic is basedon a
set of actions that can be linked together by exploiting higher level languages
more suitableto address the scale of the Web. On this multi-organization scale,
applications can be influencedby different context events generated by the
environment where they run. Handling theseevents requires run-time adaptations
of the application’s behaviour to react, properly and quickly,to changes. The
paper addresses these needs by proposing a programming paradigm based
on”autonomic service compositions”, i.e. compositions that are able
to self-change their structure,according to a specific life-cycle, to allow for
the continuation of execution, even if unexpectedevents arise. The approach
exploits autonomic computing and reasoning for taking decision oninformation
collected during processes execution. Autonomic actions on composition
structuresare performed using Event Condition Action rules and a set of
meta-operations. The approachis detailed, analysed and discussed with reference
to some examples derived from a real-worldapplication.
KEYWORDS:
Service Composition;
Self-Management; Software Adaptation; Autonomic computing.