/docs/user/metacatquery.html - Annotate - Metacat - Ecoinformatics Redmine

metacat/docs/user/metacatquery.html @ 3783

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+<!--
   * metacatquery.html
+  *
   *      Authors: Jivka Bojilova
   *    Copyright: 2000 Regents of the University of California and the
   *               National Center for Ecological Analysis and Synthesis
   *  For Details: http://www.nceas.ucsb.edu/
   *      Created: 2000 April 5
   *      Version: 0.01
   *    File Info: '$Id$'
+  *
   * October Meeting SDSC, 2000
 -->
 <HTML>
 <HEAD>
 <TITLE>Metacat</TITLE>
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+<link rel="stylesheet" type="text/css" href="./default.css">
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+</HEAD>
 <BODY>
   <table width="100%">
     <tr>
       <td class="tablehead" colspan="2"><p class="label">Queries and Results</p></td>
       <td class="tablehead" colspan="2" align="right">
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   </table>
   <P>The Metacat Server provides
   an interface for searching of metadata stored in the Metacat database.
   <P> <img alt="architecture diagram of a Metacat query" src="metadataquery.gif">
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+  <br><br><b>Steps to perform a query in Metacat</b>
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+  <ol>
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+    <li>A pathquery document is created from the search criteria provided through
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+    the servlet parameters.</li>
     <li>This pathquery document is sent to DBQuery where it
     is processed and translated into SQL statements.</li>
     <li>The SQL statements are executed against the database and the resultsets
     are translated into an xml document of doctype "resultset".</li>
     <li>The resultset document is either returned directly to the client as XML
     or is transformed through XSLT and returned as HTML.</li>
   </ol>
   <b>The Pathquery Document</b>
   <pre>
    &lt;pathquery version="1.0"&gt;
       &lt;meta_file_id&gt;unspecified&lt;/meta_file_id&gt;
       &lt;querytitle&gt;unspecified&lt;/querytitle&gt;
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+      &lt;returnfield&gt;dataset/title&lt;/returnfield&gt;
       &lt;returnfield&gt;keyword&lt;/returnfield&gt;
       &lt;returnfield&gt;originator/individualName/surName&lt;/returnfield&gt;
       &lt;returndoctype&gt;eml://ecoinformatics.org/eml-2.0.1&lt;/returndoctype&gt;
       &lt;returndoctype&gt;eml://ecoinformatics.org/eml-2.0.0&lt;/returndoctype&gt;
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+      &lt;querygroup operator="UNION"&gt;
         &lt;queryterm casesensitive="false" searchmode="contains"&gt;
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+          &lt;value&gt;Datos&lt;/value&gt;
           &lt;pathexpr&gt;dataset/title&lt;/pathexpr&gt;
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+        &lt;/queryterm&gt;
         &lt;queryterm casesensitive="false" searchmode="contains"&gt;
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+          &lt;value&gt;plant&lt;/value&gt;
           &lt;pathexpr&gt;keyword&lt;/pathexpr&gt;
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+        &lt;/queryterm&gt;
       &lt;/querygroup&gt;
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+  &lt;/pathquery&gt;
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+  </pre>
   <p>The pathquery document was designed to be flexible enough to query specific
   fields of any XML document.  It also allows the client to specify which fields
   from a returned document are returned in the initial resultset.  Each
   &lt;returnfield&gt; parameter specifies a field which the DB will return
   for any query hit.  The returndoctype fields allows the client to limit the
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+  type of documents to be returned.  If no returndoctype element , all document types are returned.
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+  A &lt;querygroup&gt; creates an AND or an OR statement of the &lt;queryterm&gt;s
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+  in the group.  The operator can be UNION or INTERSECT.  A &lt;queryterm&gt;
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+  defines the actual field against which the query is being performed.  The value
   of the queryterm that we are quering for is encased in &lt;value&gt; tags.
   The &lt;pathexpr&gt; tag specifies an exact path to which you want to restrict
   the search.  A &lt;pathexpr&gt; tag which contains the keyword returndoc is
   a special case which is discussed in <a href="./packages.html">Packages and
   Relations</a>.</p><br>
   <b>The Resultset Document</b><br>
   <p>When the pathquery document is submitted and processed, Metacat returns
   another XML document called a resultset document.<p>
   <pre>
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+      &lt;resultset&gt;
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+        &lt;query&gt;
           &lt;pathquery version="1.0"&gt;
             &lt;meta_file_id&gt;unspecified&lt;/meta_file_id&gt;
             &lt;querytitle&gt;unspecified&lt;/querytitle&gt;
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+            &lt;returnfield&gt;dataset/title&lt;/returnfield&gt;
             &lt;returnfield&gt;keyword&lt;/returnfield&gt;
             &lt;returnfield&gt;originator/individualName/surName&lt;/returnfield&gt;
             &lt;returndoctype&gt;eml://ecoinformatics.org/eml-2.0.1&lt;/returndoctype&gt;
             &lt;returndoctype&gt;eml://ecoinformatics.org/eml-2.0.0&lt;/returndoctype&gt;
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+            &lt;querygroup operator="UNION"&gt;
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+                  &lt;queryterm casesensitive="false" searchmode="contains"&gt;
                       &lt;value&gt;Datos&lt;/value&gt;
                       &lt;pathexpr&gt;dataset/title&lt;/pathexpr&gt;
                   &lt;/queryterm&gt;
                   &lt;queryterm casesensitive="false" searchmode="contains"&gt;
                      &lt;value&gt;plant&lt;/value&gt;
                      &lt;pathexpr&gt;keyword&lt;/pathexpr&gt;
                   &lt;/queryterm&gt;
            &lt;/querygroup&gt;
          &lt;/pathquery&gt;
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+        &lt;/query&gt;
         &lt;document&gt;
           &lt;docid&gt;nceas.44.1&lt;/docid&gt;
           &lt;docname&gt;resource&lt;/docname&gt;
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+          &lt;doctype&gt;eml://ecoinformatics.org/eml-2.0.1&lt;/doctype&gt;
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+          &lt;createdate&gt;2001-01-12 16:12:06.0&lt;/createdate&gt;
           &lt;updatedate&gt;2001-01-12 16:12:06.0&lt;/updatedate&gt;
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+          &lt;param name="dataset/title"&gt;Datos Meteorologicos&lt;/param&gt;
           &lt;param name="keyword"&gt;intertidal&lt;/param&gt;
           &lt;param name="originator/individualName/surName"&gt;Smith&lt;/param&gt;
         &lt;/document&gt;
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         &lt;document&gt;
           &lt;docid&gt;nceas.42.1&lt;/docid&gt;
           &lt;docname&gt;resource&lt;/docname&gt;
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+          &lt;doctype&gt;eml://ecoinformatics.org/eml-2.0.1&lt;/doctype&gt;
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+          &lt;createdate&gt;2001-01-12 16:11:31.0&lt;/createdate&gt;
           &lt;updatedate&gt;2001-01-12 16:11:31.0&lt;/updatedate&gt;
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+          &lt;param name="dataset/title"&gt;Ocean Surface Temperature&lt;/param&gt;
           &lt;param name="keyword"&gt;Plant&lt;/param&gt;
           &lt;param name="originator/individualName/surName"&gt;Henry&lt;/param&gt;
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+       &lt;/document&gt;
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+      .....
       &lt;/resultset&gt;
   </pre>
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+  <p>The first element in the resultset is &lt;query&gt;.  Its content is just
   the pathquery document.  The resultset always returns
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+  the pathquery document that created it in the &lt;query&gt; tag.  The next
   major tag is &lt;document&gt;.  Each XML document returned by the query
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+  is represented by a &lt;document&gt; tag.  The default document information returned
   is docid, docname, doctype, doctitle, createdate and
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+  updatedate.  The param tags are present if the document found contained
   the returnfield chosen in the pathquery document.  The name attribute of the
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+  param tag is the full path to the node specified by the returnfield. <p>
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