A Declarative XML-RL Update Language

With the wide adoption of XML, it is a natural requirement to allow users to directly update XML documents. This paper formally presents a novel XML update language for updating XML documents based on the XML-RL language. Taking the advantages of XML-RL data model that give us the ability to comprehend XML data from database point of view, the XML-RL update language provides users with the ability to make change to XML documents in a simple, natural and effective way. It provides a uniform framework that is advantageous over other XML update languages in the following ways. (1) The binding variables that can refer to any kind of XML object provide a very powerful and intuitive way to express updates. Moreover, using such binding variable to bind object name, we do not need rename operation. (2) The user is not required to create an object before it can be inserted into the document. We can update not only object values, but also object name or both with the help of binding variable. (3) The multi-level update does not need nested query-update expressions. (4) The updates to more than one XML document can be expressed in just one update statement. (5) It supports IDREFS update which is lacking in other update languages. (6) It incorporates some of features of object oriented database and logic programming language, which make it easier for user to understand and to use.