A Visual Interface for Querying a CASE Repository

linear query representations formulated by e.g. SQL, as evidenced from some empirical studies [4][5][6]. As a consequence, different types of users, especially novices, can learn and use the query facilities in a more intuitive way, without needing to memorize the database schema or the grammar of the query language. Adapting this query mechanism into CASE can benefit CASE users in a similar way. Further, the current CASE environments normally consist of a set of visual tools. Consequently, a visual query tool could better suit the CASE tool users. In this paper we propose a visual user interface for formulating Boolean queries over a CASE repository. The work is motivated by the successful adoption of the visual query paradigm in the conventional database area. With its graphical query representation system, such a query system could ease the user’s tasks of formulating database queries when compared with linear textual query representations. In this paper, we describe the adopted human-computer interaction techniques in this visual query interface. Specifically, we illustrate those features that seek to solve “CASE-specific” query tasks, or that are distinct from other visual query systems. We show how with this query interface the user can easily formulate arbitrary Boolean queries over a CASE repository. Because of the distinct characteristics of CASE, a visual query tool for a CASE repository faces more challenges than those found in conventional database systems. These challenges come from the complexity of the information stored in the repository, derived from the three features of abstraction, construction and representation [1]. Abstraction means that the CASE repository contains information at several consecutive levels of abstraction. Construction indicates that the information is more complicated than in conventional database systems, and is subject to a number of semantic constraints. Representation means that a piece of conceptual information in CASE can be viewed through several representation forms (diagram, matrix, text, etc.). Our concentration in this paper is to address the construction part of the complexity, i.e. how to formulate queries with a complicated repository structure and confirming to a specific semantic constraint, which is called relationship integrity.