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<title>Class: Metacat</title>
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<div id="classHeader">
<table class="header-table">
<tr class="top-aligned-row">
<td><strong>Class</strong></td>
<td class="class-name-in-header">Metacat</td>
</tr>
<tr class="top-aligned-row">
<td><strong>In:</strong></td>
<td>
<a href="../files/lib/metacat_rb.html">
lib/metacat.rb
</a>
<br />
</td>
</tr>
<tr class="top-aligned-row">
<td><strong>Parent:</strong></td>
<td>
Object
</td>
</tr>
</table>
</div>
<!-- banner header -->
<div id="bodyContent">
<div id="contextContent">
<div id="description">
<h1><a href="Metacat.html">Metacat</a> Client Library</h1>
<h2>What is it</h2>
<p>
A client for the <a href="Metacat.html">Metacat</a> data catalog. For a
description of <a href="Metacat.html">Metacat</a>, see <a
href="http://knb.ecoinformatics.org/software/metacat">knb.ecoinformatics.org/software/metacat</a>
For now, this client does not implement all features of the API. Rather, it
focuses on querying and returning <a href="Eml.html">Eml</a> metadata
objects from either pathqueries or docid’s. Should you find yourself
using methods other than find() very often, you may be veering from the
original intent.
</p>
<h2>Examples</h2>
<h3>Read metadata for a public document</h3>
<pre>
require 'lib/metacat.rb'
metacat = Metacat.new('http://data.piscoweb.org/catalog/metacat')
eml = metacat.find(:docid => 'pisco.10.4')
puts eml.docid
=> 'pisco.10.4'
</pre>
<h3>Log into <a href="Metacat.html">Metacat</a> and read <a href="Eml.html">Eml</a> metadata. Then logout</h3>
<pre>
username = 'uid=cburt,o=PISCO,dc=ecoinformatic,dc=org'
password = *****
Metacat.new('http://data.piscoweb.org/catalog/metacat', username, password) do |metacat|
eml = metacat.find(:docid => 'pisco.10.3')
start, end = eml.temporal_coverage
puts "start: #{start}, end: #{end}"
end
</pre>
<h3>Search for oceanographic data</h3>
<pre>
metacat = Metacat.new('http://data.piscoweb.org/catalog/metacat')
pathquery = '...' # see example at http://knb.ecoinformatics.org/software/metacat/metacatquery.html
docs = metacat.find(:squery => pathquery)
docs.each { |eml| puts eml.docid }
</pre>
<h3>Find and write a data_table to local disk</h3>
<pre>
Metacat.new('http://data.piscoweb.org/catalog/metacat', username, password) do |metacat|
file = File.new('tmp', 'w+')
# using a block you can avoid loading the whole file into memory!
metacat.read('data_table.1.1') do |fragment|
file.write(fragment)
end
file.close
end
</pre>
</div>
</div>
<div id="method-list">
<h3 class="section-bar">Methods</h3>
<div class="name-list">
<a href="#M000072">find</a>
<a href="#M000071">logged_in?</a>
<a href="#M000073">login</a>
<a href="#M000074">logout</a>
<a href="#M000070">new</a>
<a href="#M000075">read</a>
<a href="#M000076">squery</a>
</div>
</div>
</div>
<!-- if includes -->
<div id="section">
<!-- if method_list -->
<div id="methods">
<h3 class="section-bar">Public Class methods</h3>
<div id="method-M000070" class="method-detail">
<a name="M000070"></a>
<div class="method-heading">
<a href="Metacat.src/M000070.html" target="Code" class="method-signature"
onclick="popupCode('Metacat.src/M000070.html');return false;">
<span class="method-name">new</span><span class="method-args">(path_to_metacat, options = {}) {|self| ...}</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<h3 class="section-bar">Public Instance methods</h3>
<div id="method-M000072" class="method-detail">
<a name="M000072"></a>
<div class="method-heading">
<a href="Metacat.src/M000072.html" target="Code" class="method-signature"
onclick="popupCode('Metacat.src/M000072.html');return false;">
<span class="method-name">find</span><span class="method-args">(args)</span>
</a>
</div>
<div class="method-description">
<p>
Returns either an array of <a href="Eml.html">Eml</a> documents(or nil) if
:squery is passed or a single <a href="Eml.html">Eml</a> document(or nil)
if passed :docid. This function <em>will</em> <em>not</em> return a data
table, only <a href="Eml.html">Eml</a> objects.
</p>
<p>
If you need to retrieve a data table or other document, use read()
</p>
<p>
Examples:
</p>
<pre>
Metacat.find(:docid => 'cbs_10.1')
Metacat.find(:squery => xml_path_query)
</pre>
</div>
</div>
<div id="method-M000071" class="method-detail">
<a name="M000071"></a>
<div class="method-heading">
<a href="Metacat.src/M000071.html" target="Code" class="method-signature"
onclick="popupCode('Metacat.src/M000071.html');return false;">
<span class="method-name">logged_in?</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Check if the metacat instance has a session cookie
</p>
</div>
</div>
<div id="method-M000073" class="method-detail">
<a name="M000073"></a>
<div class="method-heading">
<a href="Metacat.src/M000073.html" target="Code" class="method-signature"
onclick="popupCode('Metacat.src/M000073.html');return false;">
<span class="method-name">login</span><span class="method-args">(username, password)</span>
</a>
</div>
<div class="method-description">
<p>
Logs into metacat using ldap authentication. Usernames are complex, such as
‘uid=cburt,o=PISCO,dc=ecoinformatics,dc=org’
</p>
<p>
Raises <a href="MetacatPermissionDenied.html">MetacatPermissionDenied</a>
exception on fail
</p>
<p>
Example
</p>
<pre>
metacat.login('uid=cburt,o=PISCO,dc=ecoinformatics,dc=org', '******')
=> true
</pre>
</div>
</div>
<div id="method-M000074" class="method-detail">
<a name="M000074"></a>
<div class="method-heading">
<a href="Metacat.src/M000074.html" target="Code" class="method-signature"
onclick="popupCode('Metacat.src/M000074.html');return false;">
<span class="method-name">logout</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<div id="method-M000075" class="method-detail">
<a name="M000075"></a>
<div class="method-heading">
<a href="Metacat.src/M000075.html" target="Code" class="method-signature"
onclick="popupCode('Metacat.src/M000075.html');return false;">
<span class="method-name">read</span><span class="method-args">(docid, options = {}) {|xml or data_table fragment| ...}</span>
</a>
</div>
<div class="method-description">
<p>
Reads a specified document from metacat. If xml is found, a REXML::Document
will be returned
</p>
<p>
When reading text data tables, it should be noted that loading the entire
large file can consume an enormous amount of memory. To avoid this, read
can be passed a &block. The block will recieve fragments of the file as
it comes in.
</p>
<p>
Examples: Reading an EML document
</p>
<pre>
metacat.read('eml_doc.1.1')
=> <REXML::Document >
</pre>
<p>
Writing a data table to disk
</p>
<pre>
file = File.new('tmp', 'w+')
metacat.read('data_table.1.1') do |fragment|
file.write(fragment)
end
file.close
</pre>
<p>
Reading an entire data table into memory
</p>
<pre>
data_table = metacat.read('data_table.1.1')
</pre>
</div>
</div>
<div id="method-M000076" class="method-detail">
<a name="M000076"></a>
<div class="method-heading">
<a href="Metacat.src/M000076.html" target="Code" class="method-signature"
onclick="popupCode('Metacat.src/M000076.html');return false;">
<span class="method-name">squery</span><span class="method-args">(squery)</span>
</a>
</div>
<div class="method-description">
<p>
Uses the metacat pathquery search and returns the xml response as a string.
For query format information, see <a
href="http://knb.ecoinformatics.org/software/metacat/metacatquery.html">knb.ecoinformatics.org/software/metacat/metacatquery.html</a>
</p>
</div>
</div>
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