With the growing importance of XML in data exchange, much research has been done in providing flexible query mechanisms to extract data from XML documents. In this paper, we focus on the query evaluation in an XML streaming environment, in which data streams arrive continuously and queries have to be evaluated even before all the data of an XML document is available. We will propose an algorithm for this issue, working in O(|T|⋅Qleaf) time and O(|T|⋅Qleaf) space, where Tleaf stands for the number of the leaf nodes in a document tree T and Qleaf for the number of the leaf nodes in a query tree Q.
Chen, Yangjun, "On the XML Data Stream and Xpath Queries" (2008). CONF-IRM 2008 Proceedings. 42.