Web Services Qos Access To Technology And Systems Design And Implementation

With the vigorous development of Web Services technologies, Web Services QoS has been paid much more attention. Recent research mainly focused on QoS-based applications, such as QoS-based dynamic composition and negotiation. However, few paper and research referred to the area of QoS acquisition today.On the other hand, under the circumstances of basic functions of assets library are getting more completed and the number of software assets stored in the library is growing fast. There is an urgent requirement for the library to enhance its quality assessment mechanism on software assets (expecially Web Services), in order to help users know the quality level of services better.For these demands, this paper took the acquisition of QoS as a topic, which includes the analysis of Web service call process, approaches of the QoS acquisition, and how to establish a centric platform called QoS Information Server to receive, store and process on QoS data. This QoS Information Server is responsible for receiving QoS data collected by all the collection source and estimating on QoS level according to specific QoS model, as well as to provide an efficient data query interface and event-based mechanism to support scalable QoS computation. In addition, this paper also made an analysis of QoS data content, proposed a "basic" and "extensible" data model. Based on this model, we also developed a QoS data transmitting protocol.During the implementation, we get help from a lot of new technologies (such as Java NIO, StAX API), good design patterns (Obersver, Chain of Responsibility, etc.) and design principles (Dependency Inversion Principle), and also many amazing open-source projects (Apache Lucene, Apache Axis, XSocket, etc.). Finally, this paper took three Web services from "Open Software Assets Library" of Peking University as targets, put QoS data acquisition into practice to demonstrate the utility of the implmentation system.