Collaborative Open Market to Place Objects at your Service

D1.3.1 Service modelling and representation – First version

In this deliverable, we put together the baseline models for service description to be used in COMPOSE, building on the results of the project SOA4All, and with the aim of publishing service descriptions as Linked Data. Guided by real-world services from two of the project’s use cases, we also gather further relevant ontologies and we propose lightweight COMPOSEspecific vocabularies to be used in service descriptions, where we can find no suitable existing ontologies to re-use. The primary uses for service and object descriptions in COMPOSE are discovery – making services and service objects reachable and understandable, and composition – combining multiple services and service objects in higher-level, added-value services and applications. These uses guide the selection and design of vocabularies in this deliverable. The core ontology is the Minimal Service Model (MSM), which presents a simplified operationoriented understanding of services, and maps straightforwardly to WSDL descriptions. On the side of RESTful services and APIs, where WSDL is usually not available, we adopt the hRESTS microformat that gives MSM structure to plain-HTML documentation. On top of the MSM, we use SAWSDL annotations as a standard way of attaching semantics to service descriptions. To structure the semantics, we use the WSMO-Lite service semantics ontology, which distinguishes four types of service semantics: functional, nonfunctional, behavioural, and information-model semantics. The COMPOSE-specific vocabularies in this deliverable are all built on top of existing ontologies, and they use the lightweight terms of WSMO-Lite. Further, we specify terms for basic service description metadata, and we provide an initial sketch of future work in the directions of security, reputation and trust. This document should serve as a common basis for the project’s efforts around publishing, discovering, and composing services and service objects. It is not meant as a comprehensive single model that would be set in stone; rather it is the first convergence point that can kick-start dependent efforts. The common set of ontologies, whether external or COMPOSE-specific, will be maintained in a public, up-to-date resource, for the benefit of project partners as well as third parties who may reuse the work.

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