Design and Implementation of Wrappers in the Environment of Heterogeneous Information Sources

• Main Authors: Chiang, Ming-Chou, 江明洲
• Other Authors: Yang Chen-Chau
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/99231720010990597173

碩士 === 國立台灣工業技術學院 === 電子工程技術研究所 === 85 === A wrapper is a software module that provides a uniform protocol to hide the details of retrieving, input and output format in the environment of information sources. It translates the queries from mediators into the specific queries or commands of each information source. This thesis describes the design of wrappers for three kinds of information source, including relational database, WWW pages, and structured text files. For wrapping the query processing in the relational database environment, we employ a two-phase scheme to translate Loom query language into SQL byusing TRC as the intermediate representation. For the extraction of WWW pages, some string- based commands are developed to convert a set of hyperlinked HTML pages into packaged objects. Besides, we also proposea general architecture for the implementation of wrappers and specify the various components by describing their functionality and implementation technique. An application domain of the air quality monitoring is used to verify the correctness and feasibility of the operations of wrappers.