Ontology-independent and QOS-enabled dynamic composition of web services in business domains

vii, 107 leaves : ill. ; 29 cm.Includes abstract.Includes bibliographical references (leaves 102-107).This thesis proposes a novel and high-performance ontology-independent approach and methods for Quality of Services (QoS)-enabled dynamic web services discovery and composition. One proposed method uses Google distance for calculating semantic similarities instead of using the state-of-the-art ontological-based approaches in the semantic matching stage. A further new method is architected for the QoS operational matching stage of web services discovery. Moreover, the thesis proposes a hybrid approach to dynamic web services composition, called FOIQOS, consisting of using a prescriptive system for web services discovery and composition. Another problem the thesis addresses is the absence of comparisons of existing QoS-enabled composition approaches in the literature. To compare the new methods proposed in the thesis, FOIQOS and three other approaches for QOS-enabled dynamic web services composition were implemented. Experimental results show that the proposed FOIQOS approach significantly outperforms its ontology-based and heuristic-based method counterparts, in terms of both increased accuracy and reduced overhead

Web service composition : architecture, frameworks, and techniques

OASIS defines Service Oriented Architecture (SOA) as a paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains. One approach to realize SOA is Web services. A Web service is a software system that has a machine processable Web Services Description Language (WSDL) interface; other systems interact with it using SOAP messages in a manner prescribed by its description. Descriptions enable Web services to be discovered, used by other Web services, and composed into new Web services. Composition is a mechanism for rapid creation of new Web services by reusing existing ones. Web services have functional, behavioral, semantic, and non-functional characteristics. These characteristics have to be considered for composition, as they provide essential information about the services. In order to compose Web services with these characteristics, they have to be described appropriately. However, the existing techniques do not consider all these aspects together for description and composition. This thesis proposes a business model, also referred to as architecture, a description framework, and a composition framework for Web service composition. Techniques for matching, categorizing, and assembling the composite services are also proposed as a part of the composition framework. The architecture, frameworks, and techniques describe, discover, manipulate, and compose Web services by taking into account all their characteristics. The standard Web service business model is extended by the proposed business model to support Web service composition. In the model, based on their demand, the requested Web services are composed by the Web service composer. In the proposed architecture, Web services are described using the description framework languages. The proposed framework combines Semantic Annotations for WSDL and XML Schema (SAWSDL) for functional and semantic description, Message Sequence Charts (MSC) for behavioral description, and a simple and new Non Functional Specification Language (NFSL) for the non-functional properties description of Web services. It uses Higher Order Logic (HOL) for formalizing and integrating the three languages. The role of Web service composer in the architecture is realized by the composition framework. It essentially defines the architecture of the composer. In this framework, matchmaking, categorization, and assembly techniques are used to create the requested composite service. These techniques manipulate the Web services at HOL-level. The formal matchmaking technique discovers the primitive Web services by using a HOL theorem prover. The categorization and the assembly techniques manipulate the matched services and orchestrate the composite service. The concepts of the model, frameworks, and techniques are implemented, and their working is illustrated using case studies. Prototypes of the model's components (extended registry and extended requester) and the composition framework are developed, and their performance is analyzed. Case studies to illustrate the description and the composition frameworks are also presente