| 1 |
878
|
berkley
|
<!--
|
| 2 |
|
|
* metacatquery.html
|
| 3 |
|
|
*
|
| 4 |
|
|
* Authors: Jivka Bojilova
|
| 5 |
|
|
* Copyright: 2000 Regents of the University of California and the
|
| 6 |
|
|
* National Center for Ecological Analysis and Synthesis
|
| 7 |
|
|
* For Details: http://www.nceas.ucsb.edu/
|
| 8 |
|
|
* Created: 2000 April 5
|
| 9 |
|
|
* Version: 0.01
|
| 10 |
|
|
* File Info: '$Id$'
|
| 11 |
|
|
*
|
| 12 |
|
|
* October Meeting SDSC, 2000
|
| 13 |
|
|
-->
|
| 14 |
|
|
<HTML>
|
| 15 |
|
|
<HEAD>
|
| 16 |
|
|
<TITLE>Metacat</TITLE>
|
| 17 |
|
|
<link rel="stylesheet" type="text/css" href="@docrooturl@default.css">
|
| 18 |
|
|
</HEAD>
|
| 19 |
|
|
<BODY>
|
| 20 |
|
|
<table width="100%">
|
| 21 |
|
|
<tr>
|
| 22 |
|
|
<td class="tablehead" colspan="2"><p class="label">Queries and Results</p></td>
|
| 23 |
|
|
<td class="tablehead" colspan="2" align="right">
|
| 24 |
|
|
<a href="./metacatload.html">Back</a> | <a href="./metacattour.html">Home</a> |
|
| 25 |
|
|
<a href="./metacatread.html">Next</a>
|
| 26 |
|
|
</td>
|
| 27 |
|
|
</tr>
|
| 28 |
|
|
</table>
|
| 29 |
|
|
<P>The Metacat Server provides
|
| 30 |
|
|
an interface for searching of metadata stored in the Metacat database.
|
| 31 |
|
|
<P> <img alt="architecture diagram of a Metacat query" src="metadataquery.gif">
|
| 32 |
881
|
berkley
|
<br><br><b>Steps to perform a query in Metacat</b>
|
| 33 |
878
|
berkley
|
<ol>
|
| 34 |
881
|
berkley
|
<li>A pathquery document is created from the search criteria provided through
|
| 35 |
878
|
berkley
|
the servlet parameters.</li>
|
| 36 |
|
|
<li>This pathquery document is sent to DBQuery where it
|
| 37 |
|
|
is processed and translated into SQL statements.</li>
|
| 38 |
|
|
<li>The SQL statements are executed against the database and the resultsets
|
| 39 |
|
|
are translated into an xml document of doctype "resultset".</li>
|
| 40 |
|
|
<li>The resultset document is either returned directly to the client as XML
|
| 41 |
|
|
or is transformed through XSLT and returned as HTML.</li>
|
| 42 |
|
|
</ol>
|
| 43 |
|
|
|
| 44 |
|
|
<b>The Pathquery Document</b>
|
| 45 |
|
|
<pre>
|
| 46 |
|
|
<pathquery version="1.0">
|
| 47 |
|
|
<meta_file_id>unspecified</meta_file_id>
|
| 48 |
|
|
<querytitle>unspecified</querytitle>
|
| 49 |
3775
|
tao
|
<returnfield>dataset/title</returnfield>
|
| 50 |
|
|
<returnfield>keyword</returnfield>
|
| 51 |
|
|
<returnfield>originator/individualName/surName</returnfield>
|
| 52 |
|
|
<returndoctype>eml://ecoinformatics.org/eml-2.0.1</returndoctype>
|
| 53 |
|
|
<returndoctype>eml://ecoinformatics.org/eml-2.0.0</returndoctype>
|
| 54 |
878
|
berkley
|
<querygroup operator="UNION">
|
| 55 |
|
|
<queryterm casesensitive="false" searchmode="contains">
|
| 56 |
3775
|
tao
|
<value>Datos</value>
|
| 57 |
|
|
<pathexpr>dataset/title</pathexpr>
|
| 58 |
878
|
berkley
|
</queryterm>
|
| 59 |
|
|
<queryterm casesensitive="false" searchmode="contains">
|
| 60 |
3775
|
tao
|
<value>plant</value>
|
| 61 |
|
|
<pathexpr>keyword</pathexpr>
|
| 62 |
878
|
berkley
|
</queryterm>
|
| 63 |
|
|
</querygroup>
|
| 64 |
3775
|
tao
|
</pathquery>
|
| 65 |
878
|
berkley
|
</pre>
|
| 66 |
|
|
|
| 67 |
|
|
<p>The pathquery document was designed to be flexible enough to query specific
|
| 68 |
|
|
fields of any XML document. It also allows the client to specify which fields
|
| 69 |
|
|
from a returned document are returned in the initial resultset. Each
|
| 70 |
|
|
<returnfield> parameter specifies a field which the DB will return
|
| 71 |
|
|
for any query hit. The returndoctype fields allows the client to limit the
|
| 72 |
3775
|
tao
|
type of documents to be returned. If no returndoctype element , all document types are returned.
|
| 73 |
878
|
berkley
|
A <querygroup> creates an AND or an OR statement of the <queryterm>s
|
| 74 |
2476
|
costa
|
in the group. The operator can be UNION or INTERSECT. A <queryterm>
|
| 75 |
878
|
berkley
|
defines the actual field against which the query is being performed. The value
|
| 76 |
|
|
of the queryterm that we are quering for is encased in <value> tags.
|
| 77 |
|
|
The <pathexpr> tag specifies an exact path to which you want to restrict
|
| 78 |
|
|
the search. A <pathexpr> tag which contains the keyword returndoc is
|
| 79 |
|
|
a special case which is discussed in <a href="./packages.html">Packages and
|
| 80 |
|
|
Relations</a>.</p><br>
|
| 81 |
|
|
|
| 82 |
|
|
<b>The Resultset Document</b><br>
|
| 83 |
|
|
|
| 84 |
|
|
<p>When the pathquery document is submitted and processed, Metacat returns
|
| 85 |
|
|
another XML document called a resultset document.<p>
|
| 86 |
|
|
|
| 87 |
|
|
<pre>
|
| 88 |
3775
|
tao
|
<resultset>
|
| 89 |
878
|
berkley
|
<query>
|
| 90 |
|
|
<pathquery version="1.0">
|
| 91 |
|
|
<meta_file_id>unspecified</meta_file_id>
|
| 92 |
|
|
<querytitle>unspecified</querytitle>
|
| 93 |
3775
|
tao
|
<returnfield>dataset/title</returnfield>
|
| 94 |
|
|
<returnfield>keyword</returnfield>
|
| 95 |
|
|
<returnfield>originator/individualName/surName</returnfield>
|
| 96 |
|
|
<returndoctype>eml://ecoinformatics.org/eml-2.0.1</returndoctype>
|
| 97 |
|
|
<returndoctype>eml://ecoinformatics.org/eml-2.0.0</returndoctype>
|
| 98 |
878
|
berkley
|
<querygroup operator="UNION">
|
| 99 |
3775
|
tao
|
<queryterm casesensitive="false" searchmode="contains">
|
| 100 |
|
|
<value>Datos</value>
|
| 101 |
|
|
<pathexpr>dataset/title</pathexpr>
|
| 102 |
|
|
</queryterm>
|
| 103 |
|
|
<queryterm casesensitive="false" searchmode="contains">
|
| 104 |
|
|
<value>plant</value>
|
| 105 |
|
|
<pathexpr>keyword</pathexpr>
|
| 106 |
|
|
</queryterm>
|
| 107 |
|
|
</querygroup>
|
| 108 |
|
|
</pathquery>
|
| 109 |
878
|
berkley
|
</query>
|
| 110 |
|
|
|
| 111 |
|
|
<document>
|
| 112 |
|
|
<docid>nceas.44.1</docid>
|
| 113 |
|
|
<docname>resource</docname>
|
| 114 |
3775
|
tao
|
<doctype>eml://ecoinformatics.org/eml-2.0.1</doctype>
|
| 115 |
878
|
berkley
|
<createdate>2001-01-12 16:12:06.0</createdate>
|
| 116 |
|
|
<updatedate>2001-01-12 16:12:06.0</updatedate>
|
| 117 |
3775
|
tao
|
<param name="dataset/title">Datos Meteorologicos</param>
|
| 118 |
|
|
<param name="keyword">intertidal</param>
|
| 119 |
|
|
<param name="originator/individualName/surName">Smith</param>
|
| 120 |
|
|
</document>
|
| 121 |
878
|
berkley
|
|
| 122 |
|
|
<document>
|
| 123 |
|
|
<docid>nceas.42.1</docid>
|
| 124 |
|
|
<docname>resource</docname>
|
| 125 |
3775
|
tao
|
<doctype>eml://ecoinformatics.org/eml-2.0.1</doctype>
|
| 126 |
878
|
berkley
|
<createdate>2001-01-12 16:11:31.0</createdate>
|
| 127 |
|
|
<updatedate>2001-01-12 16:11:31.0</updatedate>
|
| 128 |
3775
|
tao
|
<param name="dataset/title">Ocean Surface Temperature</param>
|
| 129 |
|
|
<param name="keyword">Plant</param>
|
| 130 |
|
|
<param name="originator/individualName/surName">Henry</param>
|
| 131 |
1987
|
tao
|
</document>
|
| 132 |
878
|
berkley
|
.....
|
| 133 |
|
|
</resultset>
|
| 134 |
|
|
|
| 135 |
|
|
</pre>
|
| 136 |
881
|
berkley
|
<p>The first element in the resultset is <query>. Its content is just
|
| 137 |
|
|
the pathquery document. The resultset always returns
|
| 138 |
878
|
berkley
|
the pathquery document that created it in the <query> tag. The next
|
| 139 |
|
|
major tag is <document>. Each XML document returned by the query
|
| 140 |
881
|
berkley
|
is represented by a <document> tag. The default document information returned
|
| 141 |
|
|
is docid, docname, doctype, doctitle, createdate and
|
| 142 |
878
|
berkley
|
updatedate. The param tags are present if the document found contained
|
| 143 |
|
|
the returnfield chosen in the pathquery document. The name attribute of the
|
| 144 |
3775
|
tao
|
param tag is the full path to the node specified by the returnfield. <p>
|
| 145 |
878
|
berkley
|
|
| 146 |
|
|
<br>
|
| 147 |
|
|
<a href="./metacatload.html">Back</a> | <a href="./metacattour.html">Home</a> |
|
| 148 |
|
|
<a href="./metacatread.html">Next</a>
|
| 149 |
|
|
|
| 150 |
|
|
</BODY>
|
| 151 |
|
|
</HTML>
|