In the case of large-scale distributed environments such as the Internet, users are interested in monitoring changes to a particular web page (XML or HTML). There are many instances in which the change detection is required at a finer granularity, such as changes to links, images, phrases or keywords in a page. WebVigiL is a general-purpose, change monitoring, notification and presentation system for web pages. It handles specification, management, and propagation of customized changes as requested by a user in an efficient way. When the user specifies an URL, it may contain frames instead of a single content page; this entails additional pages to be fetched from the frames for detecting changes. In this paper we propose different approaches for detecting changes over pages containing frames and generalizing it in terms of depth. We also address the case of monitoring multiple web pages for different change types with a single request. As there are no presentation semantics and tags, manual identification of the detected changes is difficult on a XML web page. Once detected, changes have to be notified to the user in a meaningful manner. In this paper we also propose various presentation schemes to display the changes computed on XML pages.
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