Community Modules

This document describes the GeoServer community module process. It is a guide that describes how the GeoServer project takes in contributions from the community.

In GeoServer a module can fall into one of three classes:

  • core, those modules which GeoServer requires to function and are distributed with the main GeoServer distribution
  • extension, plug-ins available as separate artifacts from the main distribution
  • community, experimental or unstable modules which are not part of the release process

Every module added to GeoServer has its origin as a community module. If the module becomes stable enough it will eventually become part of the main GeoServer distribution either as a core module, or as an extension.

Creating a community module

Requirements

The single requirement for adding a community module is the approval of one Project Steering Committee member.

Process

The following outlines the steps to be taken in order to add a new community module.

  1. Get approval

    The first step is to get approval to add the community module. This involves first explaining to the rest of the GeoServer community the purpose and function of the extension to be added. The two best ways to do this are:

    1. send an email to the developers list, or
    2. participate in a weekly IRC meeting

    After explaining the intention, the approval of at least one Project Steering Committee member is needed before proceeding. Getting approval is easy as long as it is explained that the extension will be useful to other users or developers.

  2. Get version control access

    The next step is to create the community module in the git repository. To do this it is necessary to be granted commit status. The process for signing up for version control access is defined in the Committing section.

  3. Add a new module

    Once commit access is obtained the module can be added. All community modules live under the directory community, directly under the root of the source tree. The community modules on trunk can be found here.

    For example, from the root of the GeoServer source tree:

    [geoserver]% cd src/community
    [geoserver/src/community]% mkdir myCommunityModule
    [geoserver/src/community]% git add myCommunityModule
    [geoserver/src/community]% git commit -m "adding my community module"
  4. Add a Maven POM

    Every module in the build requires a maven pom file, pom.xml. Use the following as a template:

      <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
      <modelVersion>4.0.0</modelVersion>
    
      <parent>
        <groupId>org.geoserver</groupId>
        <artifactId>geoserver</artifactId>
        <version>2.8-SNAPSHOT</version> <!-- change this to the proper GeoServer version -->
      </parent>
    
      <groupId>org.geoserver</groupId>
      <artifactId>myCommunityModule</artifactId>
      <version>1.0-SNAPSHOT</version>
      <packaging>jar</packaging>
      <name>My Community Module</name>
    
      <dependencies>
        <!-- add any dependencies your module has here -->
      </dependencies>
    </project>
    

    Add the file to the root of the new community module, myCommunityModule/pom.xml

  5. Add a build profile

    The final step involves adding the new module to the maven build, and in particular adding a build profile for it. To do this:

    1. Edit community/pom.xml and add the following inside of the <profiles> element:

      <profiles>
        ...
        <profile>
          <id>myCommunityModule</id>
          <modules>
            <module>myCommunityModule</module>
          </modules>
        </profile>
      </profiles>
      
    2. Edit web/app/pom.xml and add the following inside of the <profiles> element:

         <profiles>
           ...
           <profile>
             <id>myCommunityModule</id>
             <dependencies>
               <dependency>
                  <groupId>org.geoserver</groupId>
                  <artifactId>myCommunityModule</artifactId>
                  <version>1.0-SNAPSHOT</version>
                </dependency>
             </dependencies>
           </profile>
         </profiles>
      
      .. warning::
      
         If the community module depends on any other community modules,
         they too should be included in the profile definition.
      
      .. warning::
      
         Ensure that the name of the profile matches the name of the
         community module
      

Promoting a community module

Once a community modules becomes “stable”, it may be promoted to a core or extension module. Which depends on the nature of the community module. If the module is plug-in based (i.e. it provides functionality that some users may want, but others may not) then it should become an extension. Otherwise it should become a core module.

Requirements

The following properties must hold true in order to promote a community module:

  1. The module has at least a “handful” of users

    In order to avoid cluttering the main code base, only those community modules which are of interest to at least 3 users (this may include the maintainer) are promoted.

  2. The module has a designated and active maintainer

    Every core and extension module requires a module maintainer. The job of the maintainer is to fix bugs and address issues which arise with the module. If a community module is promoted and the maintainer “drops off”, the module is in danger of being demoted back to community status.

  3. The module is considered “stable” by the majority of the PSC

    A module will only be promoted if it is deemed “stable” by the majority of the PSC. Those PSC members deeming it “unstable” must provide a reasonable justification for the assertion.

  4. The module maintains 40% test coverage

    A minimum of 40% test coverage must be maintained by the module in order to be promoted. Of course higher coverage is encouraged. The more test coverage a community module the more credibility it gets.

  5. The module has no IP violations

    The module must not contain any code with a license or copyright that violates the GPL.

  6. The module has a page in the user manual

    Each module needs a page in the user manual documenting its function and usage. Tutorials and walk-throughs are encouraged.

  7. The maintainer has signed the GeoServer Contributor Agreement

    OSGeo retains all copyright on code released as part of GeoServer. Since core and extension modules are released along with the rest of GeoServer, the maintainer of said modules must agree to assign copyright of code to OSGeo.

Process

  1. Submit a GeoServer Improvement Proposal

    To promote a community module the contributor must create a GeoServer Improvement Proposals (GSIP). The proposal must then go through the regular feedback and voting process.

  2. Move the module

    Once the proposal is accepted, the next step is to move the module out of the community space. Where the module ends up depends on whether it is being promoted to a core module, or an extension.

    Core modules

    Core modules live under the root of the source tree:

    [geoserver]% mv src/community/myCommunityModule src/
    [geoserver]% git add src/myCommunityModule
    [geoserver]% git add --all src/community/myCommunityModule
    [geoserver]% git commit -m "promoting my community module to a core module"

    Extensions

    Extension modules live under the extension directory, under the root of the source tree:

    [geoserver]% mv src/community/myCommunityModule src/extension
    [geoserver]% git add src/extension/myCommunityModule
    [geoserver]% git add --all src/community/myCommunityModule
    [geoserver]% git commit -m "promoting my community module to an extension"
  3. Update the build

    Once the module has been moved, the maven build must be updated.

    Core modules

    1. Edit community/pom.xml and remove the profile for the community module

    2. Edit pom.xml under the root of the source tree and add a module entry:

      <modules>
        ...
        <module>myCommunityModule</module>
      </modules>
    3. Edit web/app/pom.xml and move the dependency on the community module

      into the main dependencies section of the pom. Then remove the profile

    Extensions

    1. Copy the profile for the community module from community/pom.xml to extension/pom.xml
    2. Remove the profile from community/pom.xml
    3. Remove the release descriptor from community/pom.xml contained in the maven-assembly-plugin configuration section
    4. Remove the dependency from community/release/pom.xml
  4. Update the release process

    The next step is to include the new module in the release process.

    Core modules

    1. Edit release/src.xml and add an <include> for the module:

      ...
      <moduleSets>
        <moduleSet>
         ...
         <include>org.geoserver:myCommunityModule</include>
        </moduleSet>
      </moduleSets>
      ...

    Extensions

    1. Create a new directory under release/extensions which matches the name of the extension

    2. Add the following to the new directory:

      1. A license called ‘<module>-LICENSE.txt’ which contains the license for the extension

      2. A readme called ‘<module>-README.txt’ which contains instructions on how to install the extension

        Warning

        Don’t skip this step.

      3. Any “static” files that are required by the extension (example would be a proprietary driver not available for download via maven)

    3. Create a release descriptor called ‘ext-<module>.xml’ under the release directory which follows the following structure (where “%module%” is the name of the module):

         <assembly>
           <id>%module%</id>
           <formats>
             <format>zip</format>
           </formats>
           <includeBaseDirectory>false</includeBaseDirectory>
           <fileSets>
             <fileSet>
               <directory>release/extensions/%module%</directory>
               <outputDirectory></outputDirectory>
               <includes>
                 <include>*</include>
               </includes>
             </fileSet>
             <fileSet>
               <directory>release/target/dependency</directory>
               <outputDirectory></outputDirectory>
               <includes>
                 <include>%module%-*.jar</include>
               </includes>
             </fileSet>
             <fileSet>
               <directory>release/extensions</directory>
               <outputDirectory></outputDirectory>
               <includes>
                 <include>LICENSE.txt</include>
               </includes>
             </fileSet>
           </fileSets>
         </assembly>
      
      * Add additional ``include`` elements in the second ``fileSet`` for
        the jar dependencies of the module
      * Add additional ``include`` elements in the third ``fileSet`` for
        the static file dependencies of the module
      
    4. Add a dependency from release/pom.xml to the extension module:

      <dependencies>
         ...
         <dependency>
           <groupId>org.geoserver.extension</groupId>
           <artifactId>%module%</artifactId>
           <version>%version%</version>
         </dependency>
         ...
       </dependencies>
    5. Add an entry for the release descriptor to the root pom.xml of the source tree (i.e. one step up from the release directory):

      <!-- artifact assembly -->
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.1</version>
        <configuration>
          <descriptors>
           <descriptor>release/src.xml</descriptor>
           <descriptor>release/war.xml</descriptor>
           <descriptor>release/javadoc.xml</descriptor>
           <descriptor>release/bin.xml</descriptor>
           <descriptor>release/doc.xml</descriptor>
           ...
           <descriptor>release/ext-%module%.xml</descriptor>
          </descriptors>
        </configuration>
      </plugin>
    1. Update the documentation

      Add a page to the user manual for the new module.

      Todo

      Finish this by linking somewhere...

    2. Download the contributor agreement

      The final step in the process is to download and fill out the contributor agreement form. Follow the instructions on the form to submit it.

Demoting a community module

For one reason or another a module is neglected and becomes unmaintained. When this happens the GeoServer PSC essentially becomes the maintainer and may decide to do one of two things:

  1. Assume maintainership

    In this case someone (may be more than one person) on the PSC agrees to take on maintainership duties responsibilities for the module, such as bug fixing

  2. Demote the module

    If no one steps up to maintain the module it may be demoted back to community status. If and when a module is demoted depends on the circumstances. If the module is relatively “quiet” in that it just works and not many bug reports arise from it, it may be left alone and not demoted.

Requirements

The following properties must hold true in order to demote a module back to community status:

  1. The module has no designated maintainer

    The module maintainer has stepped down or is unreachable and has not been active for a number of weeks.

  2. The module is problematic

    The module contains one or more issues with blocker status, or contains a “handful” of issues with high priority.

Process

The following outlines the steps to demote a module to community status:

  1. Call for a maintainer

    Before demoting the module first try to find a new maintainer for it. Send an email to both the developer and user list advertising the module is in danger of getting pushed back to community status. Wait a few days to see if anyone steps up to take on maintainership.

  2. Move the module and update the build

    If no one steps up to take on the maintainer role, reverse the steps described here, taken to promote the module. In summary:

    1. Move the module back to the community directory
    2. Disable any of the modules release artifacts
    3. Move the profile for the module from extension/pom.xml to community/pom.xml in the case of an extension module

Stepping down from module maintainership

Often a module maintainer does not have the time or resources to continue to maintain a contribution. This is understood and is a fact of life in the open source software world. However, to relieve the burden on the project and PSC, the following steps taken by any maintainer stepping down are highly appreciated.

  1. Give notice

    The more time you can give to the project in lieu of your departure the better. Send an email to the developers list as soon as you know you will be dropping off

  2. Find a new maintainer

    While often not possible, any attempt to find a new maintainer for the module is greatly appreciated.

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