Query language requirements
The W3C Query Working Group has identified many
technical requirements:
- at least one XML syntax; at least one human-readable syntax.
- must be declarative;
- must be protocol independent;
- must respect XML data model;
- must be namespace aware;
- must coordinate with XML Schema;
- must work even if schemas are unavailable;
- must support simple and complex datatypes;
- must support universal and existential quantifiers;
- must support operations on hierarchy and sequence of document structures;
- must combine information from multiple documents;
- must support aggregation;
- must be able to transform and to create XML structures;
- must be able to traverse ID references.
In short, it must be SQL generalized to XML!