An introduction to self-healing Web services (tutorial summary)

The service-oriented approach is becoming more and more popular to integrate highly heterogeneous systems. Service-oriented architectures (SoAs) define a new flexible coordination paradigm for integrating components (services) in unstable and evolving contexts, where the high degree of flexibility and dynamism requires that available functionality be discovered at run-time and its quality parameters be negotiated dynamically. This is the case, for example, of ambient computing and automotive applications that need to cope with continuously evolving configurations. The dynamic nature of these systems precludes the a-priori identification of the components that define the system and demands for the run-time discovery and composition of such services, adding uncertainty to the system. It could be the case, for example, that a binding (request/provision) cannot span multiple executions since the changing context alters the set of available services. This means that problems related to the discovery of services should also be considered and handled at run-time. If the selection phase aborts, simply shutting down the system is not, in general, going to be a solution. The execution environment should be able to select new services and even reorganize the process to find a solution that uses what is available, if a perfect match does not exist.