Optimizing the Execution Time for Checking the Consistency of XML Documents

摘要

The problem of checking the consistency of the semantics associated with extensible markup language (XML) documents is considered. We propose a novel technique to add semantics to XML documents by attaching semantic information to the XML element tag attributes. We call this XML semantics. This approach is based on the same concept of attribute grammars (AGs), attaching and checking static semantics of programming languages through their attributes. The goal of this paper is to introduce the notions of copy rules and copy attributes that can be deployed in the XML semantics. Moreover, we will show how it can be represented in the SLXS language. The SLXS language is a description language based on XML; we have designed it to describe the semantic dependencies of XML documents. In addition, we demonstrate the copy bypass attribute propagation algorithm that can be used to eliminate the evaluation of copy attributes in copy rule chains. It dynamically replaces copy rules with non-local dependencies. Given such elimination, we get a faster attribute evaluator and avoid evaluating unnecessary attributes. Furthermore, more than half of the generated code associated with copy rules is reduced. In this way, we gain an optimization technique to evaluate and check the consistency of XML documents that may contain such attributes. Finally, we evaluate experimentally the performance benefits of our technique using a variety of XML documents.