Digital Symposium Collection 2000

A Layered Architecture for Querying Dynamic Web Content Hasan Davulcu, Juliana Freire, Michael Kifer, and I. V. Ramakrishnan   View Paper (PDF)   Return to Text and Web Databases Abstract The design of webbases, database systems for supporting Web-based applications, is currently an active area of research. In this paper, we propose a 3-layer architecture for designing and implementing webbases for querying dynamic Web content (i.e., data that can only be extracted by filling out multiple forms). The lowest layer, virtual physical layer, provides navigation independence by shielding the user from the complexities associated with retrieving data from raw Web sources. Next, the traditional logical layer supports site independence. The top layer is analogous to the external schema layer in traditional databases. Within this architectural framework we address two problems unique to webbases — retrieving dynamic Web content in the virtual physical layer and querying of the external schema by the end user. The layered architecture makes it possible to automate data extraction to a much greater degree than in existing proposals. Wrappers for the virtual physical schema can be created semi-automatically, by asking the webbase designer to navigate through the sites of interest — we call this approach mapping by example. Thus, the webbase designer need not have expertise in the language that maps the physical schema to the raw Web (this should be contrasted to other approaches, which require expertise in various Web-enabled flavors of SQL). For the external schema layer, we propose a semantic extension of the universal relation interface. This interface provides powerful, yet reasonably simple, ad hoc querying capabilities for the end user compared to the currently prevailing “canned” form-based interfaces on the one hand or complex Web-enabling extensions of SQL on the other. Finally, we discuss the implementation of the proposed architecture. References Note: References link to DBLP on the Web. [1] Sibel Adali , K. Selçuk Candan , Yannis Papakonstantinou , V. S. Subrahmanian : Query Caching and Optimization in Distributed Mediator Systems. SIGMOD Conf. 1996 : 137-148 [2] José Luis Ambite , Naveen Ashish , Greg Barish , Craig A. Knoblock , Steven Minton , Pragnesh J. Modi , Ion Muslea , Andrew Philpot , Sheila Tejada : ARIADNE: A System for Constructing Mediators for Internet Sources. SIGMOD Conference 1998 : 561-563 [3] ... [4] Paolo Atzeni , Giansalvatore Mecca , Paolo Merialdo : Semistructured und Structured Data in the Web: Going Back and Forth. 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BIBTEX @inproceedings{DBLP:conf/sigmod/DavulcuFKR99,   author    = {Hasan Davulcu and                 Juliana Freire and                 Michael Kifer and                 I. V. Ramakrishnan},    editor    = {Alex Delis and                 Christos Faloutsos and                 Shahram Ghandeharizadeh},    title     = {A Layered Architecture for Querying Dynamic Web Content},    booktitle = {SIGMOD 1999, Proceedings ACM SIGMOD International Conference                 on Management of Data, June 1-3, 1999, Philadephia, Pennsylvania,                 USA},    publisher = {ACM Press},    year      = {1999},    isbn      = {1-58113-084-8},    pages     = {491-502},    crossref  = {DBLP:conf/sigmod/99},    bibsource = {DBLP, http://dblp.uni-trier.de} } }, Copyright(C) 2000 ACM