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<!--
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* Metacatdom.html
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*
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* Authors: Jivka Bojilova
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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* For Details: http://www.nceas.ucsb.edu/
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* Created: 2000 April 5
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* Version: 0.01
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* File Info: '$Id$'
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*
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* October Meeting SDSC, 2000
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-->
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<HTML>
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<HEAD>
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<TITLE>Metacat</TITLE>
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<link rel="stylesheet" type="text/css" href="@docrooturl@default.css">
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</HEAD>
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<BODY>
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<table width="100%">
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<tr>
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<td class="tablehead" colspan="2"><p class="label">The Metacat DOM</p></td>
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<td class="tablehead" colspan="2" align="right">
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<a href="./metacatdb.html">Back</a> | <a href="./metacattour.html">Home</a> |
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<a href="./metacatload.html">Next</a>
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</td>
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</tr>
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</table>
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<P>In the Metacat DOM implementation XML documents
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are disassembled into their composite nodes. All nodes are stored as records
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in the database tables. The structure of each XML document is preserved
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by saving the parent-child relationship between the nodes.
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<ul>
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<li> Each XML document in the Metacat database starts with one root node of
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type DOCUMENT. All other nodes in the document are its children.
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The document node can
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have multiple COMMENT or PI (processing instruction) nodes and only
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one ELEMENT node. The element node is the root node of the document and will
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be pointed to by all of its children.
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<li> Each node is described as a single record in the <i>xml_nodes</i> table.
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All nodes have a unique System ID (<i>nodeid</i>). Each node stores
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the ID of
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its direct parent (in <i>parentnodeid</i>), the ID of its documents root node
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(in <i>rootnodeid</i>) and its Document ID (<i>docid</i>).
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<li> Document attributes (such as docid, doctype, etc.) are stored in
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the xml_documents table.
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<li> Unimplemented DOM features:
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<ul>
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<li> Node types: Doctype, Entity, EntityReference, Notation.
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<li> Persistant DOM interface. This would allow a DOM compliant
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editor to work with an xml document in the database as if it were
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in memory.
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<li>Object Oriented representation of each node.
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</ul>
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</ul>
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<P> <img alt="Entity Relationship Diagram of the Metacat DOM" src="metacatdom.jpg">
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<br>
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<a href="./metacatdb.html">Back</a> | <a href="./metacattour.html">Home</a> |
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<a href="./metacatload.html">Next</a>
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</BODY>
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</HTML>
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