Project

General

Profile

Download (9.58 KB) Statistics
| Revision:

metacat/docs/user/packages.html @ 4507

1 
<!--
2 
  * packages.html
3 
  *
4 
  *      Authors: Chad Berkley
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: 2001 January 23
9 
  *      Version:
10 
  *    File Info: '$ '
11 
  *
12 
  *
13 
-->
14 
<HTML>
15 
<HEAD>
16 
<TITLE>Metacat</TITLE>
17 
<link rel="stylesheet" type="text/css" href="./default.css">
18 
</HEAD>
19 
<BODY>
20 
  <table width="100%">
21 
    <tr>
22 
      <td class="tablehead" colspan="2"><p class="label">Packages and Relationships</p></td>
23 
      <td class="tablehead" colspan="2" align="right">
24 
        <a href="./metacatapi.html">Back</a> | <a href="./metacattour.html">Home</a> |
25 
        <a href="./replication.html">Next</a>
26 
      </td>
27 
    </tr>
28 
  </table>
29 
  <p>Metacat allows a user to create a virtual link between XML documents within
30 
  the system.  These links are called <i>Relationships</i> and are defined by triples
31 
  in <i>eml-dataset</i>, <i>eml-literature</i> or <i>eml-software</i> files.  A relationship can be defined between two
32 
  XML or <a href="./datafiles.html">non-XML</a> files.
33 
  The following is an example of an eml-dataset-2.0 file holding triples at the end:</p>
34
35 
  <pre>
36 
&lt;?xml version="1.0"?&gt;
37 
&lt;!DOCTYPE dataset PUBLIC "-//NCEAS//eml-dataset-2.0//EN" "eml-dataset-2.0.dtd"&gt;
38 
&lt;dataset&gt;
39 
  &lt;identifier system="null"&gt;berkley.5.3&lt;/identifier&gt;
40 
  &lt;shortName&gt;allsp&lt;/shortName&gt;
41 
  &lt;title&gt;MARINE sampling data collected between spring 1992 and fall 1996&lt;/title&gt;
42 
  &lt;originator&gt;
43 
    &lt;individualName&gt;
44 
      &lt;salutation&gt;Dr.&lt;/salutation&gt;
45 
      &lt;givenName&gt;Peter&lt;/givenName&gt;
46 
      &lt;surName&gt;Raimondi&lt;/surName&gt;
47 
    &lt;/individualName&gt;
48 
    &lt;organizationName&gt;UCSC&lt;/organizationName&gt;
49 
    &lt;positionName&gt; &lt;/positionName&gt;
50 
    &lt;address&gt;
51 
      &lt;deliveryPoint&gt;Biology Dept.&lt;/deliveryPoint&gt;
52 
      &lt;deliveryPoint&gt;A309 Earth and Marine Science Building&lt;/deliveryPoint&gt;
53 
      &lt;city&gt;Santa Cruz&lt;/city&gt;
54 
      &lt;administrativeArea&gt;CA&lt;/administrativeArea&gt;
55 
      &lt;postalCode&gt;95060&lt;/postalCode&gt;
56 
      &lt;country&gt;USA&lt;/country&gt;
57 
    &lt;/address&gt;
58 
    &lt;phone phonetype="voice"&gt;831-459-1234 x5674&lt;/phone&gt;
59 
    &lt;electronicMailAddress&gt;raimondi@biology.ucsc.edu&lt;/electronicMailAddress&gt;
60 
    &lt;onlineLink&gt; &lt;/onlineLink&gt;
61 
    &lt;role&gt;Originator&lt;/role&gt;
62 
  &lt;/originator&gt;
63 
  &lt;pubdate&gt; &lt;/pubdate&gt;
64 
  &lt;pubplace&gt; &lt;/pubplace&gt;
65 
  &lt;series&gt; &lt;/series&gt;
66 
  &lt;abstract&gt;
67 
    &lt;paragraph&gt; &lt;/paragraph&gt;
68 
  &lt;/abstract&gt;
69 
  &lt;keywordSet&gt;
70 
    &lt;keyword keywordType="null"&gt;intertidal&lt;/keyword&gt;
71 
    &lt;keyword keywordType="null"&gt;santa barbara&lt;/keyword&gt;
72 
    &lt;keyword keywordType="null"&gt;photoplot&lt;/keyword&gt;
73 
    &lt;keyword keywordType="null"&gt;quadrat&lt;/keyword&gt;
74 
    &lt;keywordThesaurus&gt; &lt;/keywordThesaurus&gt;
75 
  &lt;/keywordSet&gt;
76 
  &lt;additionalInfo&gt;
77 
    &lt;paragraph&gt; &lt;/paragraph&gt;
78 
  &lt;/additionalInfo&gt; <font color="red">
79 
  &lt;triple&gt;
80 
    &lt;subject&gt;berkley.6.1&lt;/subject&gt;
81 
    &lt;relationship&gt;isRelatedTo&lt;/relationship&gt;
82 
    &lt;object&gt;berkley.5.3&lt;/object&gt;
83 
  &lt;/triple&gt;
84 
  &lt;triple&gt;
85 
    &lt;subject&gt;berkley.7.1&lt;/subject&gt;
86 
    &lt;relationship&gt;isRelatedTo&lt;/relationship&gt;
87 
    &lt;object&gt;berkley.6.1&lt;/object&gt;
88 
  &lt;/triple&gt;
89 
  &lt;triple&gt;
90 
    &lt;subject&gt;berkley.8.1&lt;/subject&gt;
91 
    &lt;relationship&gt;isRelatedTo&lt;/relationship&gt;
92 
    &lt;object&gt;berkley.5.3&lt;/object&gt;
93 
  &lt;/triple&gt;
94 
  &lt;triple&gt;
95 
    &lt;subject&gt;berkley.8.1&lt;/subject&gt;
96 
    &lt;relationship&gt;isRelatedTo&lt;/relationship&gt;
97 
    &lt;object&gt;berkley.6.1&lt;/object&gt;
98 
  &lt;/triple&gt;
99 
  &lt;triple&gt;
100 
    &lt;subject&gt;berkley.8.1&lt;/subject&gt;
101 
    &lt;relationship&gt;isRelatedTo&lt;/relationship&gt;
102 
    &lt;object&gt;berkley.7.1&lt;/object&gt;
103 
  &lt;/triple&gt;
104 
  &lt;triple&gt;
105 
    &lt;subject&gt;berkley.14.1&lt;/subject&gt;
106 
    &lt;relationship&gt;isRelatedTo&lt;/relationship&gt;
107 
    &lt;object&gt;berkley.6.1&lt;/object&gt;
108 
  &lt;/triple&gt; </font>
109 
  &lt;temporalCoverage&gt; 1992 to 1996&lt;/temporalCoverage&gt;
110 
  &lt;geographicCoverage&gt; &lt;/geographicCoverage&gt;
111 
  &lt;taxonomicCoverage&gt; &lt;/taxonomicCoverage&gt;
112 
&lt;/dataset&gt;
113 
  </pre>
114
115 
  <b>Description of the Package File</b>
116 
  <p>Note that the doctype of this document is an unregistered NCEAS specific
117 
  DTD (-//NCEAS//eml-dataset-2.0//EN).  The package doctype is an application
118 
  property of Metacat.  Setting this property (and others) is described in
119 
  <a href="./properties.html">Setting Metacat Properties</a>.  The package file
120 
  contains <i>n</i> triples.  Each triple has a subject, relationship,
121 
  and an object.  This grouping can be read as follows:  &lt;subject&gt; has
122 
  &lt;relationship&gt; to &lt;object&gt;.  Each triple is a logical link
123 
  between the subject and object with the relationship being a description of that
124 
  link.</p>
125 
  <b>The Utility of Relations</b>
126 
  <p>Relations become useful because many XML data schemas are broken up into
127 
  multiple DTDs.  Thus, there may be many different XML files that are all
128 
  related to each other yet are stored seperately within the system.  Also,
129 
  since we, here at NCEAS, are developing Metacat for use as a metadata
130 
  repository for ecological data, we need some way of linking our metadata
131 
  to the datafiles that they describe.  Packages are the way we do this.</p>
132 
  <b>Post Processed Relations</b>
133 
  <p>The package file is inserted into Metacat as any other file is.  Its doctype
134 
  is checked against the packagedoctype property in the <a href="properties.html">
135 
  Metacat.properties file</a>.  If it is of that type, the file is sent
136 
  to a postprocessor to be analyzed and inserted into the xml_relation table.
137 
  The table looks like the following:</p>
138
139 
  <table border="1">
140 
    <tr>
141 
      <td>relationid</td><td>docid</td><td>packagetype</td>
142 
      <td>subject</td><td>subjectdoctype</td>
143 
      <td>relationship</td><td>object</td><td>objectdoctype</td>
144 
    </tr>
145 
    <tr>
146 
      <td>1</td>
147 
      <td>berkley.5</td>
148 
      <td>-//NCEAS//eml-dataset-2.0//EN</td>
149 
      <td>berkley.6.1</td>
150 
      <td>null</td>
151 
      <td>isRelatedTo</td>
152 
      <td>berkley.5.3</td>
153 
      <td>null</td>
154 
    </tr>
155 
    <tr>
156 
      <td>2</td>
157 
      <td>berkley.5</td>
158 
      <td>-//NCEAS//eml-dataset-2.0//EN</td>
159 
      <td>berkley.7.1</td>
160 
      <td>null</td>
161 
      <td>isRelatedTo</td>
162 
      <td>berkley.6.1</td>
163 
      <td>null</td>
164 
    </tr>
165 
    <tr>
166 
      <td>3</td>
167 
      <td>berkley.5</td>
168 
      <td>-//NCEAS//eml-dataset-2.0//EN</td>
169 
      <td>berkley.8.1</td>
170 
      <td>null</td>
171 
      <td>isRelatedTo</td>
172 
      <td>berkley.5.3</td>
173 
      <td>null</td>
174 
    </tr>
175 
    <tr>
176 
      <td>4</td>
177 
      <td>berkley.5</td>
178 
      <td>-//NCEAS//eml-dataset-2.0//EN</td>
179 
      <td>berkley.8.1</td>
180 
      <td>null</td>
181 
      <td>isRelatedTo</td>
182 
      <td>berkley.6.1</td>
183 
      <td>null</td>
184 
    </tr>
185 
    <tr>
186 
      <td>5</td>
187 
      <td>berkley.5</td>
188 
      <td>-//NCEAS//eml-dataset-2.0//EN</td>
189 
      <td>berkley.8.1</td>
190 
      <td>null</td>
191 
      <td>isRelatedTo</td>
192 
      <td>berkley.7.1</td>
193 
      <td>null</td>
194 
    </tr>
195 
    <tr>
196 
      <td>6</td>
197 
      <td>berkley.5</td>
198 
      <td>-//NCEAS//eml-dataset-2.0//EN</td>
199 
      <td>berkley.14.1</td>
200 
      <td>null</td>
201 
      <td>isRelatedTo</td>
202 
      <td>berkley.6.1</td>
203 
      <td>null</td>
204 
    </tr>
205 
  </table>
206
207 
  <p>Once, the system has processed the package file and inserted the relations
208 
  into the xml_relation table, the files relations are always returned to with it
209 
  in the <a href="./metacatquery.html">resultset</a> of a query.</p>
210 

    		
  

  

    
      211
    
    
      
  <b>Package Views (formerly known as 'backtracking')</b>


    		
  

  

    
      212
    
    
      
  <p>Package View is a feature that was intentionally left out of the 


    		
  

  

    
      213
    
    
      
  <a href="./Metacatquery.html">Queries and Results</a> section.  Package views 


    		
  

  

    
      214
    
    
      
  involves sending a doctype (called a returndoctype) along with a query request.  


    		
  

  

    
      215
    
    
      
  When there is a hit from that query, the system will check the doctype of the 


    		
  

  

    
      216
    
    
      
  hit document against the returndoctype.  If the doctypes do not match, 


    		
  

  

    
      217
    
    
      
  the system checks the xml_relation table to see if that document has been packed


    		
  

  

    
      218
    
    
      
  by document of that doctype. If such package document exists, it


    		
  

  

    
      219
    
    
      
  is returned instead of the one which was originally hit.  If no such


    		
  

  

    
      220
    
    
      
  package document exists, then the document which was originally hit is returned.  


    		
  

  

    
      221
    
    
      
  This allows a display system (such as a web browser) to try to display a 


    		
  

  

    
      222
    
    
      
  certain type of document.</p>


    		
  

  

    
      223
    
    
      
  <p>For example:  Take our package file from above.  Say we do a query for 


    		
  

  

    
      224
    
    
      
  "intertidal" which returns the document berkley.6 of type -//NCEAS//eml-entity-2.0//EN.


    		
  

  

    
      225
    
    
      
  However, we have set returndoctype equal to "-//NCEAS//eml-dataset-2.0//EN".


    		
  

  

    
      226
    
    
      
  When berkley.6 is hit, the system will check its package documents to see if 


    		
  

  

    
      227
    
    
      
  it is of type -//NCEAS//eml-dataset-2.0//EN.  Since it is, 


    		
  

  

    
      228
    
    
      
  (relationid 1, 2 and 4) document berkley.5 is returned instead of berkley.6.


    		
  

  

    
      229
    
    
      
  <p>From a client the returndoctype is a servlet parameter.


    		
  

  

    
      230
    
    
      
  A URL with a returndoctype would look something like: </p>


    		
  

  

    
      231
    
    
      
  <pre>http://server.domain.com/Metacat?action=query&amp;anyfield=%&amp;qformat=html&amp;returndoctype=-//NCEAS//eml-dataset-2.0//EN</pre>


    		
  

  

    
      232
    
    
      
  <p>The system then inserts the returndoctype parameter value into a pathquery


    		
  

  

    
      233
    
    
      
  document as illustrated in <a href="./metacatquery.html">Queries and Results</a>.


    		
  

  

    
      234
    
    
      
  </p>


    		
  

  

    
      235
    
    
      
  


    		
  

  

    
      236
    
    
      
  


    		
  

  

    
      237
    
    
      
  <br>


    		
  

  

    
      238
    
    
      
  <a href="./metacatapi.html">Back</a> | <a href="./metacattour.html">Home</a> | 


    		
  

  

    
      239
    
    
      
  <a href="./replication.html">Next</a>


    		
  

  

    
      240
    
    
      
  


    		
  

  

    
      241
    
    
      

    		
  

  

    
      242
    
    
      
</BODY>


    		
  

  

    
      243
    
    
      
</HTML>


    		
  









  (41-41/58)