Jyoti Jacob

CX-DIFF: a change detection algorithm for XML content and change visualization for WebVigiL

The World Wide Web is an omni-present and ever-expanding source of data. The exponential increase of information on the web has affected the manner in which it 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 for HTML and XML documents. It handles specification, management, and propagation of customized changes as requested by a user. A novel aspect of WebVigiL is its ability to detect customized changes on the content of the document. This paper deals with change detection to XML documents, and change visualization in WebVigiL. The ordered tree property of an XML document is exploited for change detection. In this paper, we propose an algorithm to handle customized change detection to the contents of XML documents based on user-intent. In addition, an optimization to this algorithm is presented that has a better performance with certain desired characteristics. We also discuss various change visualization schemes to display the changes computed by WebVigiL. We highlight the change presentation in WebVigiL and briefly describe the rest of the system.

WebVigiL: An Approach to Just-In-Time Information Propagation in Large Network-Centric Environments

In this chapter, we argue that push technology is critical for a large number of applications — traditional as well as network-centric. Push technology can be implemented in various ways depending upon the ‘openness’ of the underlying systems into which the push technology is being inserted. We have experimented with several approaches: integrated, mediated (using intelligent agents) and wrapper-based. Intelligent agents are useful for supporting push technology in situations where the underlying system/software provides some hooks but is not open to user modification. In this chapter, we first overview the need for push and pull technologies. We then provide an overview of active capability for detecting changes in databases and other structured environments.

WebVigiL: user profile-based change detection for HTML/XML documents

With the exponential increase of information on the web, the emphasis has shifted from mere viewing of information to efficient retrieval and notification of selective information. Currently, users have to poll the pages manually to check for changes of interest, resulting in waste of resources and associated high cost. Hence, an efficient and effective change detection and notification mechanism is needed. WebVigiL, a general-purpose, active capability-based information monitoring and notification system, 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 document, based on user intent. In this paper, we propose two different algorithms to handle change detection to contents of semi-structured and unstructured documents. Though the approach taken is general, we will explain the change detection in the context of HTML (unstructured) and XML (semistructured) documents. We also provide a simple change presentation scheme to display the changes computed. We highlight the change detection in the context of WebVigiL and briefly describe the rest of the system.

A learning-based approach for fetching pages in WebVigiL

The World Wide Web is an omni-present and an ever-expanding source of data. Data on the web is constantly increasing and changing. Many a times, users are interested in specific changes to the data on the web. Currently, in order to detect changes of interest, users have to poll the pages periodically and check for the changes of interest. WebVigiL is a general-purpose information monitoring and notification system. It handles the specification, intelligent fetch, detection, and propagation of changes as requested by a user while meeting the quality of service requirements. We use the active capability in the form of event-condition-action (ECA) rules, and a combination of push/pull paradigm for change monitoring. In this paper, we present an overview of the specification language and the run time management of sentinels. We discuss in detail the use of ECA rules for fetching and the adaptive learning algorithm used for fetching pages. We conclude with the implementation status of WebVigiL.

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

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.

Expressive Profile Specification and Its Semantics for a Web Monitoring System

World wide web has gained a lot of prominence with respect to information retrieval and data delivery. With such a prolific growth, a user interested in a specific change has to continuously retrieve/pull information from the web and analyze it. This results in wastage of resources and more importantly the burden is on the user. Pull-based retrieval needs to be replaced with a push-based paradigm for efficiency and notification of relevant information in a timely manner. WebVigiL is an efficient profile-based system to monitor, retrieve, detect and notify specific changes to HTML and XML pages on the web. In this paper, we describe the expressive profile specification language along with its semantics. We also present an efficient implementation of these profiles. Finally, we present the overall architecture of the WebVigiL system and its implementation status.