Wide Web
نویسندگان
چکیده
World Wide Web Anthony Tomasic INRIA Rocquencourt Rocquencourt, France [email protected] R emy Amouroux Bull Grenoble, France [email protected] Philippe Bonnet Bull Grenoble, France [email protected] Olga Kapitskaia INRIA Rocquencourt Rocquencourt, France [email protected] Hubert Naacke INRIA Rocquencourt Rocquencourt, France [email protected] Louiqa Raschid University of Maryland College Park, Maryland, USA [email protected] Abstract The Distributed Information Search COmponent (Disco) is a prototype heterogeneous distributed database that accesses underlying data sources. The Disco prototype currently focuses on three central research problems in the context of these systems. First, since the capabilities of each data source is di erent, transforming queries into subqueries on data source is di cult. We call this problem the weak data source problem. Second, since each data source performs operations in a generally unique way, the cost for performing an operation may vary radically from one wrapper to another. We call this problem the radical cost problem. Finally, existing systems behave rudely when attempting to access an unavailable data source. We call this problem the ungraceful failure problem. Disco copes with these problems. For the weak data source problem, the database implementor de nes precisely the capabilities of each data source. For the radical cost problem, the database implementor (optionally) de nes cost information for some of the operations of a data source. The mediator uses this cost information to improve its cost model. To deal with ungraceful failures, queries return partial answers. A partial answer contains the part of the nal answer to the query that was produced by the available data sources. The current working prototype of Disco contains implementations of these solutions and operations over a collection of wrappers that access information both in les and on the World Wide Web.
منابع مشابه
بررسی بهره گیری پژوهش گران دانشگاه تربیت مدرس از وب جهانگستر ‹World Wide Web›
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تاریخ انتشار 1997