User interface of DFQL: an object-oriented approach

Abstract

In recent years, many graphical approaches have been proposed to life the inconvenience of text-based query language among end-users. The new query language called DFQL (DataFlow Query Language) is a fully graphical interface to the relational model based on a dataflow paradigm. It only requires users to connect some well-defined operators which have been given an equivalent one-to-one correspondent functionality (or construct) in traditional query language (SQL in this case). All of the power of current query languages and sufficient expressive power and functionality are retained. But some shortcomings of DFQL user interface still exist. This thesis is to introduce a more ease-to-use and ease-to-learn user interface, so the shortcomings we found in DFQL user interface can be lifted and the productivity and power of the new version of DFQL can be increased. We have adopted object-oriented programming approach in our implementation and the benefits of using object-oriented programming in our development are also discussed.