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| <title>Layout of Feature Metadata</title> |
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| <h1>Layout of Feature Metadata</h1> |
| <p>PDE Build has always used features as a kind of grouping mechanism specifying what exactly should be built. With p2, this idea of a feature as a group has been extended, resulting a more than a single installable unit (IU) being generated per feature.</p> |
| From build's perspective, a feature contributes three things: |
| <ul> |
| <li>A grouping of nested features and plug-ins.</li> |
| <li>The (optional) feature jar itself that contains the feature.xml, license files, etc.</li> |
| <li>A mechanism to <a href="pde_rootfiles.htm">contribute root files</a> to the install.</li> |
| </ul> |
| |
| <p>When using the <a href="pde_p2_integration.htm">metadata generator</a> introduced in 3.4, we end up with the following structure for feature "<tt>org.example.platform</tt>":</p> |
| <table border="5" cellspacing="0" cellpadding="1" width="95%" align="center"> |
| <tr> |
| <td width="320"><tt>org.example.platform.feature.group</tt></td> |
| <td>This is the top level grouping IU for the feature, it will have requirements on all the features and plug-ins that were included and required by the feature.xml. It also includes a requirement on the |
| nested <tt>org.example.platform.feature.jar</tt></td> |
| </tr> |
| <tr><th colspan="2"> |
| <table border="1" cellspacing="0" align="right" style="width:98%"> |
| <tr><td width="300"><tt>org.example.platform.feature.jar</tt></td> |
| <td>This is the IU representing the feature jar itself. It has an LDAP filter <div align="center">"<tt>(org.eclipse.update.install.features=true)</tt>"</div>which causes the feature jar to only be installed if the profile defines that property. |
| This IU also has a requirement on the actual <tt>org.example.platform_1.0.0.jar</tt> artifact. |
| <p>If the feature does not define "<tt>bin.includes</tt>" in its build.properties file, then this feature jar IU will not be generated.</p></td></tr> |
| </table> |
| </th></tr> |
| </table> |
| |
| <p>Notice this IU structure does not include anything for the root files contributed by the feature. Instead a build using the metadata generation placed all rootfiles together into a single IU and artifact.</p> |
| <p>New in 3.5 is the <a href="pde_p2_builds.htm">p2 publisher</a>. If we use PDE Build's <a href="pde_p2_buildtasks.htm"><tt>eclipse.gatherFeature</tt></a> task to publish the feature from source, we instead get root file IUs corresponding to the feature that contributed them. In this case, we end up with metadata as follows:</p> |
| <table border="5" cellspacing="0" cellpadding="1" width="95%" align="center"> |
| <tr> |
| <td width="370"><tt>org.example.platform.feature.group</tt></td><td>The top level grouping IU for the feature</td> |
| </tr> |
| <tr><th colspan="2"> |
| <table border="1" cellspacing="0" align="right" style="width:98%"> |
| <tr><td width="350"><tt>org.example.platform.feature.jar</tt></td><td>The feature jar IU.</td></tr> |
| <tr><td><tt>org.example.platform_root</tt><br> |
| <tt>org.example.platform_root.<ws>.<os>.<arch></tt></td> |
| <td>These are the root file IUs. The feature.group will include a root IU per platform for which the feature contributes files. The root IU itself has a requirement on the actual binary artifact from a p2 artifact repository (eg <tt>binary/org.example.platform_root.gtk.linux.x86_1.0.0</tt>) that contains the files.</td></tr> |
| </table> |
| </th></tr> |
| </table> |
| |
| <p>The use of the new p2 publisher instead of the old metadata generator allows for much finer grain control over how root files are delivered for products.</p> |
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