Research On Web Service Resource Management Based On Open Network Application Service Models

The OSI/RM and Internet were essentially designed as a network interconnection platform addressing universal access issues among computer systems. However, application systems were out of the scope of OSI/RM, although a layer called Application had been added on top of the platform to perform common support for applications. The fact that OSI/RM lacks the open Application-Layer service and interface definitions blurs the demarcation between network applications and Application Layer, leading to a situation that support functions offered by network platforms can hardly be encapsulated and delivered to applications in a unified and effective manner. Applications are thus tightly coupled with Application Layer, resulting in poor portability, especially in a distributed environment. In this dissertation, the ONAS (Open Network Application Service) Model in the context of OSI/RM was introduced with the aim to clearly set the boundary between applications and network. It was discussed in this dissertation on how to simplify the development of network applications by offering common support functions through explicitly well-defined Network Application Service Interfaces (NASI). And Web services were deliberately chosen to investigate the above design ideas.Over the years, the Web has evolved from a hypertext/hypermedia exchange tool to a business application support platform. Recent years have also witnessed the emergence of Web services to adapt to the evolution. In fact, Web services have become the common portals for a variety of applications not only in C/S mode but also in P2P mode. Benefited from advantages such as well encapsulation, loose coupling and high integration, Web services can be extensively reused to assemble network applications. However, there are still a few problems left unsolved in different stages (service modeling, publishing, discovery, composition, execution, etc.) spanning the Web service life cycle, which hampers the further development and wider adoption of Web services. This dissertation is devoted to solutions to a few critical Web service resource management issues in different stages from the perspective of ONAS Model. The contributions to Web service resource management include:(1) Proposed the ServUnity platform providing a unified approach for Web service modeling, storing, and discovering to bridge the gap among diverse Web services such as W3C Web Services(i.e. WSDL), RESTful Services and general Web APIs to achieve unified management. Specifically, ServUnity is supported by the following research work:? The Unified Service Graph Model (USGM):a high-level abstraction of different service languages, which models heterogeneous services as service graphs by means of W3C Resource Description Framework (RDF) and enables unified service modeling, publishing and discovery. ? Service graph conversion schemes and the Service Knowledge Base (SKB): automatic conversion algorithms for standard-based service types (such as WSDL, Yahoo! Pipes, etc.), interactive conversion with semi-automated assistance for non-standard-based service types (such as RESTful Service). On the basis of the generated service graphs, SKB is constructed for extensive semantics mining and sensible service selection decisions.? A unified Web service query engine over SKB supported by the standard RDF query language SPARQL and the new Cost-based Service Chain Optimization (CSCO) algorithm to meet different requirements in different application scenarios.(2) Proposed the Collaborative Web Service Composition (CWSC) scheme based on Space-filling Curve and Distributed Hashing Table:It solves QoS-aware service composition problem by matching new requests with distributed solution-bases to avoid intensive computation as with traditional Mathematical Programming approaches, and provide better scalability and reliability than centralized Case Based Reasoning (CBR) approaches.(3) Proposed a new approach called DOLCO (Decentralized Orchestration with Local Centralized Orchestration) for composite Web service execution:It improves composite service execution performance with affinity-based multi-proxies by combining the advantages of traditional CO (Centralized Orchestration) and DO (Decentralized Orchestration), resulting in better system concurrency and reliability than CO and higher utility of proxies than DO at average request rate. A few backup proxies can be used to cope with peak request traffic via dynamic proxy configuration to reduce proxy failure.The final contribution of this dissertation is, on the basis of ONAS Model, the introduction of a new open application interconnection model called NTSP-DAS/RM (Network Transport Support Platform-Distributed Application Service/Relation Model) as discussed in Chapter7, which challenges OSI/RM from the perspective of application interconnections. It simplifies the interaction between the NTSP and distributed application systems by returning the Application Layer back to application systems. Analysis has shown that NTSP-DAS RM is more superior over ONAS Model discussed in Chapter1, considering that information exchange between network platform and applications can be greatly reduced and it is also more flexible to adapt to heterogeneous networking environment.