CD-JRA-2.3.3 Requirements for Service Registries in Dynamic Environments and Evaluation of Existing Service Registries

Web service registries are tools for the implementation of loosely-coupled service-based systems. For instance, business processes query registries in order to find services which implement functionality that is needed in the process, and adaptable service compositions need to be aware of which alternatives are available for each service. Furthermore, there is a clear interrelation between end-to-end quality provisioning and monitoring, and service registries, since SLA monitoring and enforcement is based on the availability of a service repository providing an expressive set of metadata. Even more, with the advent of the Internet of Services, an Internet-scale Web service ecosystem with unique scale and heterogeneity characteristics, a number of new challenges for the next generation of Web service registries will arise. First of all, the sheer size of the ecosystem (in terms of number of clients, providers and services) will cause a need for new scalable service discovery mechanisms built on the notions of the Internet. This includes not only discovery of atomic services, but also of task flows (ad hoc service mashups). Additionally, the distributed and heterogeneous nature of the Internet of Services asks for new data dissemination methods between physically and logically disjoint registry entities, which work in spite of missing, untrusted, inconsistent and wrong data. Further challenging requirements are going to be put forward by mobile, human-provided and ad hoc services, which are common in the Internet of Services. These services are volatile in nature, and need to be actively tracked by the service registries. Finally, another class of challenges is introduced by the human factor in the Internet of Services -- since services are often consumed and provided by humans, new means of evaluating service performance based on user-perceived and fuzzy Quality of Experience metrics need to be devised. In this deliverable we describe these requirements for the next generation of service registries for large-scale service environments in detail, and explain why we consider existing registry approaches as not sufficient for these environments. The deliverable provides the baseline research topics to be covered by the ``registry segment'' of the work package WP-JRA-2.3 in S-Cube; research questions steering the second part of the work package focussing on adaptation are described within the deliverable CD-JRA-2.3.2.

CD-JRA-2.3.3_Requirements_for_service_registries_in_dynamic_environments_and_evaluation_of_existing_service_registries.pdf — PDF document, 1031Kb