Service orientation fosters a high-level model for distributed applications development, which is based on the discovery, composition and reuse of existing software services. However, the heterogeneity among current service-oriented technologies renders the important task of service discovery tedious and ineffective. This dissertation proposes a new approach to address this challenge. Specifically, it contributes a framework supporting the unified discovery of heterogeneous services, with a focus on web, peer-to-peer, and grid services. The framework comprises a service query language and its enacting service discovery engine. Overall, the proposed solution is characterized by generality and flexibility, which are ensured by appropriate abstractions, extension points, and their sup- porting mechanisms. The viability, performance, and effectiveness of the proposed framework are demonstrated by experimental measurements.
Most of the currently existing languages for service discovery fail to address the heterogeneity in service descriptions and service discovery mechanisms. In @cite_13 @cite_9 , the authors propose the use of XQuery to express queries over service descriptions that are constructed according to specific schemas. Similarly, in @cite_17 @cite_24 , service queries can only be evaluated against WSDL documents. In an effort to address the need for multi-dimensional query formulation, the approach proposed in @cite_12 defines certain extensions to the UDDI specification, still queries are only compliant with registries of that type. Also, numerous approaches that have adopted existing semantic service description languages to express service queries, as for example in @cite_22 , are naturally confined to limited sets of available services.
@cite_22 @cite_9 @cite_24 @cite_13 @cite_12 @cite_17
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The increasing availability of web services demands for a discovery mechanism to find services that satisfy our requirement. UDDI provides a web wide registry of web services, but its lack of an explicit capability representation and its syntax based search provided produces results that are coarse in nature. We propose to base the discovery mechanism on OWL-S. OWL-S allows us to semantically describe web services in terms of capabilities offered and to perform logic inference to match the capabilities requested with the capabilities offered. We propose OWL-S UDDI matchmaker that combines the better of two technologies. We also implemented and analyzed its performance. The requirements of service discovery are spread everywhere as service discovery is the prerequisite of resource sharing, data integration and process collaboration in the network environments. In this paper, a unified service discovery framework Service CatalogNet is presented to cover many application scenarios including grid environment. We introduce the service description model in Service CatalogNet which can describe non-functional features by dynamic contexts and is supported by the semantic query engine. We also propose the unified service discovery mechanism and give the evaluations of the algorithm in terms of number of messages and query time. Web services have acquired enormous popularity among software developers. This popularity has motivated developers to publish a large number of Web service descriptions in UDDI registries. Although these registries provide search facilities, they are still rather difficult to use and often require service consumers to spend too much time manually browsing and selecting service descriptions. This paper presents a novel search method for Web services called WSQBE that aims at both easing query specification and assisting discoverers by returning a short and accurate list of candidate services. In contrast with previous approaches, WSQBE discovery process is based on an automatic search space reduction mechanism that makes this approach more efficient. Empirical evaluations of WSQBE search space reduction mechanism, retrieval performance, processing time and memory usage, using a registry with 391 service descriptions, are presented. In this paper, we propose the Web Service Discovery Architecture (WSDA). At runtime, Grid applications can use this architecture to discover and adapt to remote services. WSDA promotes an interoperable web service discovery layer by defining appropriate services, interfaces, operations and protocol bindings, based on industry standards. It is unified because it subsumes an array of disparate concepts, interfaces and protocols under a single semi-transparent umbrella. It is modular because it defines a small set of orthogonal multi-purpose communication primitives (building blocks) for discovery. These primitives cover service identification, service description retrieval, data publication as well as minimal and powerful query support. The architecture is open and flexible because each primitive can be used, implemented, customized and extended in many ways. It is powerful because the individual primitives can be combined and plugged together by specific clients and services to yield a wide range of behaviors and emerging synergies. Web services technology has generated a lot interest, but its adoption rate has been slow. This paper discusses issues related to this slow take up and argues that quality of services is one of the contributing factors. The paper proposes a new Web services discovery model in which the functional and non-functional requirements (i.e. quality of services) are taken into account for the service discovery. The proposed model should give Web services consumers some confidence about the quality of service of the discovered Web services. The web-services stack of standards is designed to support the reuse and interoperation of software components on the web. A critical step in the process of developing applications based on web services is service discovery, i.e. the identification of existing web services that can potentially be used in the context of a new web application. Discovery through catalog-style browsing (such as supported currently by web-service registries) is clearly insufficient. To support programmatic service discovery, we have developed a suite of methods that assess the similarity between two WSDL (Web Service Description Language) specifications based on the structure of their data types and operations and the semantics of their natural language descriptions and identifiers. Given only a textual description of the desired service, a semantic information-retrieval method can be used to identify and order the most relevant WSDL specifications based on the similarity of the element descriptions of the available specifications with the query. If a (potentially partial) specification of the desired service behavior is also available, this set of likely candidates can be further refined by a semantic structure-matching step, assessing the structural similarity of the desired vs the retrieved services and the semantic similarity of their identifiers. In this paper, we describe and experimentally evaluate our suite of service-similarity assessment methods.