Ordered Backward XPath Axis Processing against XML Streams

  • Abdul Nizar M.
  • P. Sreenivasa Kumar
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5679)


Processing of backward XPath axes against XML streams is challenging for two reasons: (i) Data is not cached for future access. (ii) Query contains steps specifying navigation to the data that already passed by. While there are some attempts to process parent and ancestor axes, there are very few proposals to process ordered backward axes namely, preceding and preceding-sibling. For ordered backward axis processing, the algorithm, in addition to overcoming the limitations on data availability, has to take care of ordering constraints imposed by these axes. In this paper, we show how backward ordered axes can be effectively represented using forward constraints. We then discuss an algorithm for XML stream processing of XPath expressions containing ordered backward axes. The algorithm uses a layered cache structure to systematically accumulate query results. Our experiments show that the new algorithm gains remarkable speed up over the existing algorithm without compromising on bufferspace requirement.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Abdul Nizar M.
    • 1
  • P. Sreenivasa Kumar
    • 1
  1. 1.Dept. of Computer Science and EngineeringIndian Institute of Technology MadrasChennaiIndia

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