Characterization of diagnosability and repairability for self-healing Web Services

Executive Summary This deliverable reports on Task 5.1. It analyses the requirements for self-healability and foresees the implications on the design of Web Services, comparing to how Web Services are designed today. Starting from the concepts of diagnosability and repairability, it provides a characterization of self-healability that builds upon coupling the two later. The different faults, observables and repair actions that apply to the domain of web services are listed and explained, although our focus is put on web services workflow observation and repair in the rest of the deliverable. These are then abstracted into the conceptual objects that are manipulated in the different modeling formalims. A survey of the state of the art on diagnosability is provided and diagnosability is characterized along the state-based and the event-based approaches. Repairability is a property that has not been the focus of much investigation so far. We do provide our own view of repairability and examine the properties of repair plans with respect to repairability. We claim that different levels of repairability can be defined and analyse how repairability of a workflow could be derived from the repairability properties of basic activities. Finally, self-healability is defined and conditions for self-healability are given in terms of coupled diagnosability and repairability properties.