Abstract

The utilization of a Web services based application depends not only on meeting its functional requirements but also its non-functional requirements. The nonfunctional requirements express the quality of service (QoS) expected from a system. The QoS describes the capability of the service to meet the requirements of its consumers. In the context of Web services, considerations of QoS are critical for a number of reasons. Reliability is among the important QoS requirements of such distributed components as it enhances confidence in the services provided. Although the importance of QoS requirements are well established, they are often ignored until the end of the development cycle. Reasons cited for this are that they are difficult to define and represent precisely, and relay on entities that may not be known at early stages. This articles aims to address the challenges of incorporating the QoS at an early stage of service development and represent it in a precise manner. To achieve this goal, this paper makes use of a process model to facilitate the incorporation of the QoS attributes and Z as the specification language for its formalism. Reliability is used to exemplify the process. The Z schemas have been checked for syntax and type using the Fuzz type checker.

Highlights

  • Web services have enjoyed rapid acceptance in recent years

  • Our research presented in this article complements the works of other researchers mentioned above by catering for an early incorporation of quality of service (QoS) requirements into the development cycle

  • This paper has introduced a process for formalizing QoS attributes of Web service and demonstrated its applicability in formalizing Reliability

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Summary

A Z Specification for Reliability Requirements of a Service-based System

Graduate School of Business Leadership University of South Africa Pretoria, South Africa. The importance of QoS requirements are well established, they are often ignored until the end of the development cycle Reasons cited for this are that they are difficult to define and represent precisely, and relay on entities that may not be known at early stages. This articles aims to address the challenges of incorporating the QoS at an early stage of service development and represent it in a precise manner. To achieve this goal, this paper makes use of a process model to facilitate the incorporation of the QoS attributes and Z as the specification language for its formalism.

INTRODUCTION
RELATED WORK
IMPLEMENTATION AND DISCUSSION
FORMAL SPECIFICATION
Given Sets and Globalvariables
Abstract State Space
A Proof Obligation
Partial System Operations
Error Conditions
Findings
CONCLUSIONS AND FUTURE WORK
Full Text
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