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

The quest for certainty in population screening for cervical cancer

The thesis explores the management of the certainty/uncertainty tension in the context of cervical screening programs (CSPs). In the past, the discursive making of certainty by laboratories, health educators, and promoters, has elicited a broad public perception of a simple screening test provided as a public good in answer to a common need. However, the recent litigation 'watershed' has recast CSP technologies as problematic. The quest for solutions emerging from a desire both to 'get it right', and to avoid litigation, has produced technologies of control which among other things, perform transformed answers to the question 'How should we live?' The turn to litigation is interpreted as a transforming moment in the continually unfolding CSP trajectory. The complex conditions of the Pap test's emergence as simultaneously a problem and a solution, are located and de-composed to reveal a multiplicity of performers, performances, understandings, and interpretations within the CSP arena. Problems experienced with constitutive elements of the CSPs have arisen from a disjunction between practices, representations, expectations, and perceived outcomes of screening. Early and continuing messages about screening have failed in some cases to accord with lived experience. As the workings of the CSPs have been opened to public scrutiny in the courts and the media, old certainties have been displaced by doubt, perceptions of error, and calls for improvement. Moves to manage these revealed uncertainties have issued in newly articulated and defensive strategies for building resilience and securing continuity. Such moves to regain control and restore public confidence are manifested and embodied in the processes of accreditation, regulation, registration, quality management, and automated technologies, all of which contain the promise of better ways of going on. The opening up of the CSPs to critical scrutiny in the courts and media, has meant adapting to a different discursive milieu in which the languages of cost benefit analysis, technological advantage, TQM, and zero-error, are fused with legal constructions of morality, responsibility, and certainty to perform a significant rhetorical shift. In this altered moral milieu, there is a danger that the flexible and reflective attitude which encourages multiple, and different voices to be heard, may be overcome by the rigidities expressed and performed in an overzealous quest for certainty