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<h2><a href="https://docs.jboss.org/author/display/TEIID/Custom+Metadata+Repository">Custom Metadata Repository</a></h2>
<h4>Page <b>edited</b> by <a href="https://docs.jboss.org/author/display/~shawkins">Steven Hawkins</a>
</h4>
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<b>Comment:</b>
convertin MetadataRepository to abstract<br />
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<br/>
<h4>Changes (4)</h4>
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<table class="diff" cellpadding="0" cellspacing="0">
<tr><td class="diff-snipped" >...<br></td></tr>
<tr><td class="diff-unchanged" >h3. _Custom_ <br> <br></td></tr>
<tr><td class="diff-changed-lines" >If above provided metadata facilities are not sufficient for user's needs then user can extend <span class="diff-added-words"style="background-color: #dfd;">the</span> _MetadataRepository_ <span class="diff-deleted-words"style="color:#999;background-color:#fdd;text-decoration:line-through;">interface</span> <span class="diff-added-words"style="background-color: #dfd;">class</span> provided in the _org.teiid.api_ package to plug-in their own metadata facilities into Teiid engine. For example, use can write metadata facility that is based on reading data from database, or JCR repository etc. For setting up build environment see [Setting up the build environment]. For Example <br></td></tr>
<tr><td class="diff-unchanged" > <br>{code:JAVA|title=Sample Java Code} <br>package com.something; <br> <br></td></tr>
<tr><td class="diff-changed-lines" >public class CustomMetadataRepository extends <span class="diff-changed-words"><span class="diff-deleted-chars"style="color:#999;background-color:#fdd;text-decoration:line-through;">Base</span>MetadataRepository</span> { <br></td></tr>
<tr><td class="diff-unchanged" > @Override <br> public void loadMetadata(MetadataFactory factory, ExecutionFactory executionFactory, Object connectionFactory) <br> throws TranslatorException { <br> /* Provide implementation and fill the details in factory */ <br></td></tr>
<tr><td class="diff-deleted-lines" style="color:#999;background-color:#fdd;text-decoration:line-through;"> super.loadMetadata(factory, executionFactory, connectionFactory); <br></td></tr>
<tr><td class="diff-added-lines" style="background-color: #dfd;"> ... <br></td></tr>
<tr><td class="diff-unchanged" > } <br>} <br></td></tr>
<tr><td class="diff-snipped" >...<br></td></tr>
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</div> <h4>Full Content</h4>
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<p>Traditionally the metadata for a Virtual Database is built by Teiid Designer and supplied to Teiid engine through a VDB archive file. This VDB file contains the metadata files called INDEX files, that are then read by a specific instance of <em>MetadataRepository</em> by name <em>INDEX</em>.</p>
<p>In the Dynamic VDB scenario, currently there are two predefined facilities to define metadata</p>
<h3><a name="CustomMetadataRepository-NATIVE"></a><em>NATIVE</em></h3>
<p>This is only applicable on source models (also default), when used the metadata for the model is retrieved from the source database itself.</p>
<div class="code panel" style="border-width: 1px;"><div class="codeHeader panelHeader" style="border-bottom-width: 1px;"><b>Sample vdb.xml file</b></div><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: xml; gutter: false" style="font-size:12px; font-family: ConfluenceInstalledFont,monospace;">
<vdb name="{vdb-name}" version="1">
<model name="{model-name}" type="PHYSICAL">
<source name="AccountsDB" translator-name="oracle" connection-jndi-name="java:/oracleDS"/>
<metadata type="NATIVE"></metadata>
</model>
</vdb>
</pre>
</div></div>
<h3><a name="CustomMetadataRepository-DDL"></a><em>DDL</em></h3>
<div class="code panel" style="border-width: 1px;"><div class="codeHeader panelHeader" style="border-bottom-width: 1px;"><b>Sample vdb.xml file</b></div><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: xml; gutter: false" style="font-size:12px; font-family: ConfluenceInstalledFont,monospace;">
<vdb name="{vdb-name}" version="1">
<model name="{model-name}" type="PHYSICAL">
<source name="AccountsDB" translator-name="oracle" connection-jndi-name="java:/oracleDS"/>
<metadata type="DDL">
**DDL Here**
</metadata>
</model>
</vdb>
</pre>
</div></div>
<p>This is applicable to both source and view models. When <em>DDL</em> is defined as metadata import type, the model's metadata can be defined as DDL. See <a href="/author/display/TEIID/DDL+Metadata" title="DDL Metadata">DDL Metadata</a> for more information on how to use this feature.</p>
<div class='panelMacro'><table class='tipMacro'><colgroup><col width='24'><col></colgroup><tr><td valign='top'><img src="/author/images/icons/emoticons/check.gif" width="16" height="16" align="absmiddle" alt="" border="0"></td><td><b>Chaining more than single repository</b><br />When defining the metadata import type for a model, user can define comma separated list of importers, such that all the repository instances defined by import types are consulted in the order they have configured to gather the metadata for the given model. For example:
<div class="code panel" style="border-width: 1px;"><div class="codeHeader panelHeader" style="border-bottom-width: 1px;"><b>Sample vdb.xml file</b></div><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: xml; gutter: false" style="font-size:12px; font-family: ConfluenceInstalledFont,monospace;">
<vdb name="{vdb-name}" version="1">
<model name="{model-name}" type="PHYSICAL">
<source name="AccountsDB" translator-name="oracle" connection-jndi-name="java:/oracleDS"/>
<metadata type="NATIVE,DDL">
**DDL Here**
</metadata>
</model>
</vdb>
</pre>
</div></div>
<p>For the above model, <em>NATIVE</em> importer is first used, then DDL importer used to add additional metadata to <em>NATIVE</em> imported metadata.</p></td></tr></table></div>
<h3><a name="CustomMetadataRepository-Custom"></a><em>Custom</em></h3>
<p>If above provided metadata facilities are not sufficient for user's needs then user can extend the <em>MetadataRepository</em> class provided in the <em>org.teiid.api</em> package to plug-in their own metadata facilities into Teiid engine. For example, use can write metadata facility that is based on reading data from database, or JCR repository etc. For setting up build environment see <a href="/author/display/TEIID/Setting+up+the+build+environment" title="Setting up the build environment">Setting up the build environment</a>. For Example</p>
<div class="code panel" style="border-width: 1px;"><div class="codeHeader panelHeader" style="border-bottom-width: 1px;"><b>Sample Java Code</b></div><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px; font-family: ConfluenceInstalledFont,monospace;">
package com.something;
public class CustomMetadataRepository extends MetadataRepository {
@Override
public void loadMetadata(MetadataFactory factory, ExecutionFactory executionFactory, Object connectionFactory)
throws TranslatorException {
/* Provide implementation and fill the details in factory */
...
}
}
</pre>
</div></div>
<p>Then build a JAR archive with above implementation class and create file named <em>org.teiid.metadata.MetadataRepository</em> in <em>META-INF/services</em> directory with contents</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px; font-family: ConfluenceInstalledFont,monospace;">
com.something.CustomMetadataRepository
</pre>
</div></div>
<p>Now that the JAR file has been built, this needs to be deployed in the JBoss AS as module under <em><jboss-as>/modules</em> directory. Follow the below steps to create a module.</p>
<ul>
<li>Create a directory <em><jboss-as>/modules/com/something/main</em></li>
</ul>
<ul>
<li>Under this directory create "module.xml" file that looks like</li>
</ul>
<div class="code panel" style="border-width: 1px;"><div class="codeHeader panelHeader" style="border-bottom-width: 1px;"><b>Sample module.xml file</b></div><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: xml; gutter: false" style="font-size:12px; font-family: ConfluenceInstalledFont,monospace;">
<?xml version="1.0" encoding="UTF-8"?>
<module xmlns="urn:jboss:module:1.0" name="com.something">
<resources>
<resource-root path="something.jar" />
</resources>
<dependencies>
<module name="javax.api"/>
<module name="javax.resource.api"/>
<module name="org.jboss.teiid.common-core"/>
<module name="org.jboss.teiid.teiid-api" />
</dependencies>
</module>
</pre>
</div></div>
<ul>
<li>Copy the jar file under this same directory. Make sure you add any additional dependencies if required by your implementation class under dependencies.</li>
</ul>
<ul>
<li>Restart the server</li>
</ul>
<p>The below XML fragment shows how to configure the VDB with the custom metadata repository created</p>
<div class="code panel" style="border-width: 1px;"><div class="codeHeader panelHeader" style="border-bottom-width: 1px;"><b>Sample vdb.xml file</b></div><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: xml; gutter: false" style="font-size:12px; font-family: ConfluenceInstalledFont,monospace;">
<vdb name="{vdb-name}" version="1">
<model name="{model-name}" type="PHYSICAL">
<source name="AccountsDB" translator-name="oracle" connection-jndi-name="java:/oracleDS"/>
<metadata type="{metadata-repo-module}"></metadata>
</model>
</vdb>
</pre>
</div></div>
<p>Now when this VDB gets deployed, it will call the <em>CustomMetadataRepository</em> instance for metadata of the model. Using this you can define metadata for single model or for the whole VDB pragmatically. Be careful about holding state and synchronization in your repository instance. <tt>MetadataRepository</tt> instances are created on a per vdb basis and may be called concurrently for the load of multiple models.</p>
<p>See the <tt>MetadataFactory</tt> and the <tt>org.teiid.metadata</tt> package javadocs for metadata construction methods and objects. If you use your own DDL and call the <tt>MetadataFactory.parse(Reader)</tt> method.</p>
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