E. Keramopoulos (Greece), T. Ptohos (UK), and P. Pouyioutas (Cyprus)
Graphical Query Languages, Query Language, OODBM
The Graphical Object Query Language (GOQL) is a graphical query language that complies with the ODMG standard and runs on top of the o2 DBMS. The language provides users with the User's View (UV) and the Folders Window (FW), which serve as the foundation upon which end-users can pose ad-hoc queries. The UV is a graphical representation of any underlying ODMG scheme. Among its advantages is that it hides from end-users most of the perplexing details of the object-oriented database model, such as methods, hierarchies and relationships. To achieve this, the UV does not distinguish between methods, attributes and relationships, it encapsulates is-a hierarchies and it utilises a number of desktop metaphors whose semantics can be easily understood by end-users. The Folders Window is a condensed version of the UV and provides the starting point for constructing queries. In this paper, we demonstrate, using an example, the UV and the FW and the way they support the construction of graphical queries. We also discuss GOQL's system architecture, its various components and the way these components interact to generate the UV and the FW and to provide an ad hoc query construction and evaluation mechanism. We conclude by briefly addressing issues related to the implementation of the GOQL system architecture and the portability of GOQL across different DBMS platforms.
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