Evaluation of web-specific goal oriented requirements language models with quantitative reasoning

Abstract

In this paper, we propose to evaluate Web-specific Goal Driven Models to choose amongst various design alternatives, deal with conflicts, check completeness and reaffirm the sanity of the model. The work is based on Web specific User Requirements Notation (WebURN), which is an enhancement of a goal and scenario based standard, User Requirements Notation (URN). We present the forward reasoning approach for finding the satisfaction level of the root/parent goals from the sub-goals in the goal model. The Quantitative Reasoning method called Forward Reasoning and Evaluation: Numeric (FREN) is apt when enough domain knowledge is there and precise results are expected. We propose a Quantitative Reasoning and Evaluation approach in this paper wherein the requirements engineer has an estimate of the satisfaction level of tasks and knows the priorities of various goals and sub-goals. The rules for propagation of satisfaction values from the leaves to the root level goals are specified in detail. The approach is then applied to the Webspecific Goal driven Requirements models for evaluation. The methodology has been implemented in the WebURN tool, built upon Microsoft Visio for editing and analyzing the WebURN diagrams. The results of evaluations are also compared with other prominent approaches in the area of Goal oriented Requirements Engineering. The methodology used for evaluation enables choice amongst design alternatives, resolves conflicts automatically and incorporates the role of priority in making design decisions.