Change detection technique of relevant web documents

Internet is evolving at a very rapid pace, the focus is now not only on viewing the information but also to detect selective changes in the information. It has become necessary to develop a system which can detect changes in the webpages in the minimum time. Specifically, if the webpages concerned are topic - specific, then it becomes quite crucial to get the information regarding any updates in those webpages as soon as possible. For example - if the webpages concerned are of academicians, then any change in their contact information should be responded via the change detection system. This paper discusses a webpage change detection system to detect the changes in the Web by using Web crawler. The proposed method also gives the notification to the user to compare the old and modified webpages. A new algorithm for detecting content changes as well as structural changes in the webpages is discussed. The detection of changes across the older and newer versions of the webpage is performed by first transforming the webpage into tree-like structure. The corresponding subtrees formed are first compared with their hashmaps to detect any kind of changes whether structural or in content. For retrieving any specific change, the comparison takes place only between the above found changed subtrees.