Path stream group level encoding: Efficient wireless XML streaming

Abstract

In this paper, we propose an efficient encoding for XML information dissemination scheme in mobile computing where conserving power and time is a critical task. We define a novel structure called Path Stream Group Level (PSGL) node for streaming XML data and selective download of XML document. A XML document may contain many elements with same name. But each element having same name with different XML tree path information can have various meaning in XML document. Therefore, our encoding scheme uses Location Path information of XML document to uniquely identify a node and groups its elements having same name and location path into PSGL node. Each PSGL node structure includes Level Number, Node Name, Location Path, Child Index, Sibling Index, Attribute Value List, Text Value List, Select Bit String (SBS) coding and SBS count. Level number helps in tuning into particular level of XML document tree where the result node of query or first predicate condition resides in Xpath expression for selective download of XML document. The indices and Value Lists helps in an efficient XML query processing. Thus PSGL encoding scheme exploits the XML document object model in terms of depth and level order tree traversals for XML parsing and streaming. Simple path query and twig pattern queries can be processed efficiently due to parent-child and siblings relationship coded in SBS coding.