Implementation of the GOQL language

The Graphical Object Query Language (GOQL) is a graphical query language that complies with the ODMG 3.0 standard and runs on top of the o2 DBMS. GOQL provides users with the User's View (UV) and the Folders Window (FW), which serve as the foundation upon which end-users 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 the hierarchies and it utilises a number of desktop metaphors whose semantics can be easily understood by end-users. The FW is a condensed version of the UV and provides the starting point for constructing queries. We demonstrate the UV and the FW and 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 mechanism. We also present the screen interface of the language.