CX-DIFF: A change detection algorithm for XML content and change presentation issues for WebVigiL

Abstract

The exponential increase of information on the web has affected the manner in which the information is accessed, disseminated and delivered. The emphasis has shifted from mere viewing of information to efficient retrieval and monitoring of selective changes to information content. Hence, an effective monitoring system for change detection and notification based on user-profile is needed. WebVigiL is a general-purpose, active capability-based information monitoring and notification system, which handles specification, management, and propagation of customized changes as requested by a user. The emphasis of change detection in WebVigiL is to detect customized changes on the content of the document, based on user intent. As XML is an ordered semi-structured language, detecting customized changes to part of the value of the text nodes and even portion of the content spanning multiple text nodes of an ordered XML tree is difficult. In this paper, we propose an algorithm to handle customized change detection to content of XML documents based on user-intent. An optimization to the algorithm is presented that has a better performance for XML pages with certain characteristics. We also discuss various change presentation schemes to display the changes computed. We highlight the change detection in the context of WebVigiL and briefly describe the rest of the system. © Springer-Verlag Berlin Heidelberg 2003.