ELF: A Constraint-Aware XQuery Engine for Processing XML Streams with Minimized Memory Footprint

XML and XQuery have been widely accepted as the standard data representation and query language for web applications. When the input consists of a large amount of XML tokens, the main memory buffer requirement in XML stream processing can be significant, which might also lead to a significant CPU consumption due to the manipulation cost on the buffered data. To provide real-time responses, serious challenges in memory utilization are faced by the XQuery evaluation over XML streams. In many practical applications, XML streams are generated following a pre-defined semantic constraint such as the document type definition (DTD) and XML schema.