Accurate Usage Models for Effective Web Testing and Quality Improvemen

Software quality is generally characterized by the absence of observable problems and satisfaction of user expectations. For the web applications, reliability, usability and security are identified as the primary quality attributes. Markov operational profile (Markov OP) is a type of usage models for large applications involving state transitions such as web applications. Such usage models not only help us ensure and maximize product reliability, but can also be used to understand user behavior, guide user interface design, and fine-tune system performance and usability.;Markov OP can be constructed based on actual usage of the application by target users recorded in existing web logs. Initial models constructed before maintenance and evolution may not reflect actual usage of the updated application accurately. Consequently, accuracy of the initial Markov OP could deteriorate over maintenance and evolution. We develop a method to update the initial Markov OP using existing information sources, including activity diagrams commonly used in web development activities and task models commonly used in user interface development (UID) and user centered design (UCD).;Markov OP shares some common characteristics with activity diagrams or task models which describe the updated web application in terms of user activities or tasks. Therefore, we update the initial Markov OP and improve its accuracy by analyzing ts differences with the activity diagrams or with the task models. We have applied our method in a web application to provide an initial validation of its applicability and effectiveness.;The accuracy of Markov OP would affect the effectiveness of quality assurance and testing activities. We examined the impact of accurate usage models on reliability, test coverage, and test efficiency. A case study is carried out to quantify this impact. We found supporting evidence that accurate Markov OP improves reliability, test coverage, and test efficiency.