Exposing and Aggregating Non-functional Properties in SOA from the Perspective of the Service Consumer

Non-functional properties (NFPs) represent an important facet of service descriptions, especially when a Service Oriented Architecture (SOA) approach is used. An effective SOA service development approach requires the identification, specification, implemen-tation, aggregation, management and monitoring of service-related NFPs. However, at this point in time, NFPs are either not handled at all or handled partially in proprietary ways. The goal of this thesis is to encourage their availability for use. In this thesis, the focus is on the NFPs relevant from the perspective of service consumers, in opposition to the perspective of service providers (or developers) and to multi-perspectives. In other words, the scope covers only the NFPs that need to be pub-lished to help service consumers determine whether a given service is an appropriate one for their needs (e.g., description of NFPs to be attached to the service along with the functionality description). This thesis provides the following contributions to the SOA knowledge base: definition of a domain-independent catalogue comprising 17 NFPs relevant to the descriptions of atomic services from the perspective of service consumers. These NFPs have been derived from a literature review and have been vali-dated via a two-step survey; formalization of NFP representation by defining data structures to enable quantifying and codifying them, together with a corresponding XML schema; definition, implementation and validation of algorithms to aggregate the NFPs of the composite service based on the NFPs of its underlying services, with a discussion of the NFP aggregation limitations; definition of a modeling approach for the NFP-aware selection of services, which involves aspect-oriented modeling with the User Requirements Nota-tion, in the context of SOA; integration of NFP descriptions into the Web Services Description Language (WSDL); and definition and use of the discriminator operator in service composition, to en-able the creation of fault-tolerant composite services. Overall, this work contributes to research by providing better insight on the nature, rele-vance, and composability of NFPs in a service engineering context. As for industrial im-pact, this work contributes a validated collection of NFPs with a concrete syntax and composition algorithms ready to be used for defining, selecting, and composing NFP-driven services and for evolving current SOA-related standards