Schema-based Scheduling of Event Processors and Buffer Minimization for Queries on Structured Data Streams

TL;DR

This paper presents FluX, an extension of XQuery for event-based processing of XML streams, along with an algorithm to optimize query execution by minimizing buffer usage through schema-aware scheduling.

Contribution

It introduces FluX, a new language for event-based XML query processing, and an algorithm that optimizes query execution by leveraging DTD constraints to reduce buffer requirements.

Findings

Efficient rewriting of XQueries into FluX using order constraints.

Buffer minimization achieved through schema-aware scheduling.

Experimental results demonstrate improved performance and resource usage.

Abstract

We introduce an extension of the XQuery language, FluX, that supports event-based query processing and the conscious handling of main memory buffers. Purely event-based queries of this language can be executed on streaming XML data in a very direct way. We then develop an algorithm that allows to efficiently rewrite XQueries into the event-based FluX language. This algorithm uses order constraints from a DTD to schedule event handlers and to thus minimize the amount of buffering required for evaluating a query. We discuss the various technical aspects of query optimization and query evaluation within our framework. This is complemented with an experimental evaluation of our approach.