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A Database Interface for Mobile Computers

Rafael Alonso
Eben M. Haber
Henry F. Korth
Matsushita Information Technology Laboratory
182 Nassau Street
Princeton, NJ 08542-7072


Computer-based personal information service is evolving beyond simple applications such as retrieval of phone numbers to include interaction with large, geographically distributed information bases. Concurrently, small, pen-based, mobile computers are becoming the machine of choice for personal computing. These two trends place conflicting demands on the design of database interfaces. The latter trend suggests simple interfaces that are easy-to-use, avoid keyboard use, and are suited for the small screens and small (relatively speaking) memory sizes of mobile machines. The former trend, however, suggests an increased sophistication in database interfaces, so as to provide access to the larger databases that are now part of a personal information service.

We describe a pen-based graphical database language that begins to combine these conflicting demands for simplicity and sophistication. We compare this language with previous work on graphical user interfaces designed for workstations. A prototyping effort has recently begun in our lab, and we provide a summary of its status.

1 Introduction

As computer users begin to shift more of their work to pen-based mobile computers (mobilestations), the demands placed on such machines grow. While the typical user's initial expectations are for inter-personal communication (e.g., electronic mail), simple computations (e.g., spreadsheets), and basic record-keeping (e.g., calendars), very soon they try to carry out on their mobilestations the same tasks which they are accustomed to perform on their workstations.

An important application for many computer users is accessing information stored in a database management system (DBMS). There are two important ways to access such information. These are querying the DBMS directly via a data manipulation language such as SQL, and accessing the data indirectly by using an application program with embedded database commands. Both of these interfaces are supported by most of the commercial DBMS's of which we are aware.

As applications are ported to mobilestations, users can continue to access DBMS information in the usual manner. However, the obvious approach for direct DBMS access which is using the handwriting recognition software of the mobilestations to translate pen strokes into, say, SQL