Visibly pushdown automata for streaming XML

We propose the study of visibly pushdown automata (Vpa) for processing XML documents. Vpas are pushdown automata where the input determines the stack operation, and XML documents are naturally visibly pushdown with the Vpa pushing onto the stack on open-tags and popping the stack on close-tags. In this paper we demonstrate the power and ease visibly pushdown automata give in the design of streaming algorithms for XML documents. We study the problems of type-checking streaming XML documents against SDTD schemas, and the problem of typing tags in a streaming XML document according to an SDTD schema. For the latter problem, we consider both pre-order typing and post-order typing of a document, which dynamically determines types at open-tags and close-tags respectively as soon as they are met. We also generalize the problems of pre-order and post-order typing to prefix querying. We show that a deterministic Vpa yields an algorithm to the problem of answering in one pass the set of all ans...

• Type: Conference
• Year: 2007
• Where: WWW
• Authors: Viraj Kumar, P. Madhusudan, Mahesh Viswanathan
• Keywords: Deterministic Vpa, Internet Technology, Type-checking Streaming Xml, WWW 2007, XML Documents