Combining constraints and data-flow in a visual query language

We define a graph based visual query language for object databases, called QUIVER. Most graph based query languages proposed in the literature view queries either as constraint (pattern) graphs or as data flow graphs. QUIVER, however allows constraints and data flow to be combined in queries. This combination of constraints and data flow is motivated by the need to support comprehensive object models, such as that proposed by the Object Data Management Group (ODMG). QUIVER supports all ODMG object model constructs, including computational constructs such as operations (methods). In addition, QUIVER supports computational query constructs such as subqueries and (aggregate) functions