User-defined visual query languages

Previous research in visual query languages has focused on pre-defined visual representations of data and queries, which are suitable for specific applications, but difficult to extend and generalize. We propose a meta-language to query an object-oriented database with user-defined pictures. By manipulating these pictures, the user can extract information about the data in a purely visual fashion. The proposed meta-language is rule-based and uses a constraint visual language that allows for complex displays such as graphs, bar charts, pie charts, and plot charts to be specified. Our approach extends object-oriented concepts, such as inheritance and genericity to visual query languages. We provide examples that illustrate the expressiveness of the user-defined visual languages to display and query data