Query Canvas

The query canvas is the space for the user to construct compound queries. Each sub-query is represented by a square box on the query canvas named Query n (n is an integer). Compound queries are constructed by combining sub-queries or smaller compound queries using AND, OR, and NOT operators. A sub-query in the query canvas can be modified and revalidated at any stage by using the `Edit' button. This moves the sub-query to the working canvas.

Finally, the user presses the query button to submit the query. Before translating this visual query, the system will check the query canvas to make sure there are no dangling queries. That is, all the sub-queries have to be linked using the AND, OR, or NOT operators. It will then translate the VisualMOQL query into MOQL and display the resulting string before submitting it to the query processor.