Transcript Outline
Research Directions Web Databases Will discuss Mobile MM systems Pull Access Push Access Watermarking and Steganography Rani Hoitash 1 Web Databases WWW a collection of HTML documents text, images, forms, tables information is distributed There is no unifying schema Information duplication Semi-structured data Retrieval is costly and not guaranteed optimization is important • use of similarity values • use of feedback 2 Searching Search engines Yahoo Infoseek Excite Maintain indices to the HTML pages document retrieval use of confidence values & ranking is essential Problem: based on keywords Information overload No media search capability No complex search capability single page at a time web structure is ignored page structure is ignored 3 MAVIS(microcosm) Content based retrieval for non-textual data media dependant features links are enriched by media dependant signatures feasible at a small scale hypermedia environment Harder to implement at a larger scale: it is not realistic to expect from authors to specify signatures it is not realistic to expect from indexing tools(search engine) to extract this information. The servers can do this. We can augment servers to extract such information off-line and annotated pages and links with signatures. 4 Other Systems Image surfer(Yahoo) Manual categorization of images Histogram based image retrieval (keyword) only images!! Webseek(University of Chicago) Image retrieval keyword retrieval face recognition Only images!!! Infoseek(RPI) A combined search engine (integrated) parallel execution of queries using multiple indices query translation result merging Keyword based do not provide complex query functionality 5 WebSQL(University of Toronto) WWW is a table of documents URL, title, date, etc are treated as attributes SQL is augmented to query such information E. g. Select d. url, d. title, d. length from Document d suchthat d Mentions “hypertext” where d. type=“text/html” Find all documents of type html that mentions hypertext, return the url, title, length, on modification date for such documents. 6