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.
Many service discovery frameworks have also embraced semantic web technologies to improve precision and recall of the matchmaking process, as it is reported in @cite_30 @cite_7 @cite_0 . However, such approaches mainly focus on support for the evaluation of functional search criteria, they are constrained to specific types of service brokers, and generally lack flexibility. Other efforts have tackled the challenge of multi-dimensional query evaluation @cite_5 @cite_4 , or the heterogeneity in service discovery mechanisms @cite_26 @cite_31 . Even though the proposed system architectures are characterized by flexibility, they exclusively support the discovery of web services and thus their solution is not applicable to other types of services.
@cite_30 @cite_26 @cite_4 @cite_7 @cite_0 @cite_5 @cite_31
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Service discovery has been recognized as an important aspect in the development of service-centric systems, i.e., software systems which deploy Web services. To develop such systems, it is necessary to identify services that can be combined in order to fulfill the functionality and achieve quality criteria of the system being developed. In this paper, we present a framework supporting architecture-driven service discovery (ASD)â€”that is the discovery of services that can provide functionalities and satisfy properties and constraints of systems as specified during the design phase of the development lifecycle based on detailed system design models. Our framework assumes an iterative design process and allows for the (re-)formulation of design models of service-centric systems based on the discovered services. The framework is composed of a query extractor, which derives queries from behavioral and structural UML design models of service-centric systems, and a query execution engine that executes these queries against service registries based on graph matching techniques. The article describes a prototype tool that we have developed to demonstrate and evaluate our framework and the results of a set of preliminary experiments that we have conducted to evaluate it. The growing number of web services advocates distributed discovery infrastructures which are semantics-enabled and support quality of service (QoS). In this paper, we introduce a novel approach for semantic discovery of web services in P2P-based registries taking into account QoS characteristics. We distribute (semantic) service advertisements among available registries such that it is possible to quickly identify the repositories containing the best probable matching services. Additionally, we represent the information relevant for the discovery process using Bloom filters and pre-computed matching information such that search efforts are minimized when querying for services with a certain functional QoS profile. Query results can be ranked and users can provide feedbacks on the actual QoS provided by a service. To evaluate the credibility of these user reports when predicting service quality, we include a robust trust and reputation management mechanism. 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. The capability to easily find useful services (software applications, software components, scientific computations) becomes increasingly critical in several fields. Current approaches for services retrieval are mostly limited to the matching of their inputs outputs possibly enhanced with some ontological knowledge. Recent works have demonstrated that this approach is not sufficient to discover relevant components. In this paper we argue that, in many situations, the service discovery should be based on the specification of service behavior (in particular, the conversation protocol). The idea behind is to develop matching techniques that operate on behavior models and allow delivery of partial matches and evaluation of semantic distance between these matches and the user requirements. Consequently, even if a service satisfying exactly the user requirements does not exist, the most similar ones will be retrieved and proposed for reuse by extension or modification. To do so, we reduce the problem of behavioral matching to a graph matching problem and we adapt existing algorithms for this purpose. A prototype is presented (available as a web service) which takes as input two conversation protocols and evaluates the semantic distance between them.