1 Experiences with Super , a Database Visual Environment

We present our experiences with building SUPER 1 , a database environment based on a structurally object-oriented entity-relationship model, called ERC+. SUPER is designed to be a semantically rich user-friendly front-end to existing relational or object-oriented database systems. We focus on the functionalities of visual direct manipulation interfaces of SUPER, in particular the schema and the query editors. We motivate and advocate the use of object-oriented toolboxes both to support the multi-threaded event-based dialogue of direct manipulation graphical interfaces and the implementation of data models. 1. INTRODUCTION User interfaces have evolved from command languages, where the user had a textual, sequential interaction with the computer, to graphical, direct manipulation interfaces, based on the WIMP metaphor (Windows, Icons, Menus, Pointing devices). Human-computer interaction has evolved to a multithreaded dialogue, where multiple, independent tasks are carried out simultaneously by the user. The user can switch among several tasks. In database management systems (DBMS) the users are still bound to classical textual languages as SQL. However, visual interfaces aim at relieving the user from the syntax of a command language. This implies that some graphical denotations must be adopted to display both the objects being manipulated and the functions that are used to manipulate them on the screen. Graphical data definition interfaces have achieved a large consensus. A number of commercial tools exist, which offer graphical facilities for the definition of a database schema, according to concepts of the entity-relationship (ER) approach [9]. Many prototypes that provide graphical DBMS interfaces have been developed. Some of these support graphical data definition, as [8], Sidereus [1]. DDEW [24] extends the definition process to all phases of database design, providing an integrated environment from user requirements to physical design. Several tools provide both schema definition and visual querying facilities: ISIS Many DBMS interaction tools have a restricted view of the direct manipulation paradigm [27]. Some DBMS visual interfaces only provide the user with a language that is a visual translation of textual