A Study On The Evolution Of SaaS Service On Request

With the rapid development of information technology, a new round of technological changes has arrived. In recent years, SaaS, a cloud computing service delivery model, has become a research hotspot. Software technology is expected to experience fundamental changes and bring forth far-reaching effects with the coming of new generations of cloud computing technoloegies and in-depth applications of them. And the software engineering theory for the present is inadequate in such a situation.Based on "single-instance, multi-tenant", function scalable, on-demand services, and other characteristics of SaaS software and tenant-demand driven, the conceptual framework of evolution of SaaS services is established. The OWL-S and Pi calculus and their extensions are used as the formal tools. The statute of the evolution of the demand for SaaS services, the demand for translation mapping the evolution of the operating model, model analysis are explored in depth. The evolution procces is realized from the perspectives of needs, service flows and services.The following is what this dissertation is focused on:1. To establish a conceptual framework of the SaaS service evolution. SaaS service system is analyzed from a comprehensive perspective. On the basis of the analysis, a conceptual framework of the tenant-demand driven evolution of SaaS service is established by layer.2. To put forward a formal representation method for a SaaS service requirements. Through a necessary extention of the Ontology Web Language for Service (OWL-S) to increase the positions and content descriptions of the evolution, the SaaS requirements are formally desicribed and demonstrated. The possible conflict type of SaaS service requirements are studied, as well as the conflict detection and resolution method.3. To establish a SaaS service flow evolution model. Service flow is formally described by extending the classic Pi-calculus. And service flow evolution model is established. The research covers the evolution of service flow before and after the simulation of degree. And the research covers the cluster model expansion problem. The solution to the problems are proposed. The flow of accessibility, deadlock and live lock be verified.4. To establish a SaaS incremental evolution model based on extended Pi calculus. The research covers the extention of the classic Pi calculus that enables the construction of the SaaS incremental evolution model, the atom services of SaaS service, and the demonstration and integration of the atom services. Besides, the interactive simulation theory is applied to prove the equivalence and consistency of the service evolution.With the analysis, design and implementation aforesaid, this thesis puts forth an aided SaaS evolution platform, assisting administrators and tenants complete SaaS service evolution. Through cases feasibility and practicality about the theories and methods of analysis in this paper illustrated.In short, this paper presents a tenant demand-driven SaaS service evolution method and theorizes the methods involved with an eye for the guidance of the potential SaaS software development, maintenance and operation. It provides an effective way for the realization of cloud computing software evolution environment.