Research on query previewing in networked information systems was realized with a prototype for the Global Change Master Directory (GCMD) of NASA. The implementation of this prototype showed that multi-valued data types can not be easily integrated with the query previewing ideas using the current approaches. Most of the problems lie in the data structure design of the current query preview implementations. This project suggests two possible solutions. The main idea in these approaches is the pre-calculation of finite number of discrete queries that can be asked in a query preview interface. Both of the approaches use a client-server scheme. The first approach does not transfer the pre-calculated values over the network before the execution of the query preview program. The second approach does transfer the pre-calculated values. The first approach is named as the post-fetch approach and the second one is named as the pre-fetch approach. With this project, we also compare these two approaches in terms of their performance in networked systems along with the comparison to the previous approaches.


Query Previewing, Dynamic Querying, Direct Manipulation, User Interface, Data Structures, Algorithms, Databases, Networks, Human-Computer Interaction.