Bundling a Mumble plugin

After you have built your plugin you will have a shared library for the respective target OS. While it is possible to just give users this shared library and tell them to install them, it might get inconvenient at times. Especially if you want to support your plugin for multiple OS.

Therefore Mumble provides a way to package your plugin in a user-friendly and cross-platform way.

Mumble plugin bundles are essentially zip-files with a special contents structure and the file extension .mumble_plugin instead of .zip. Such a bundle must contain a manifest.xml as a top-level entry in the archive. The manifest file is used to specify which plugin library (also bundled within the archive) is to be used for which OS and architecture.

The manifest file format

The manifest file always has to be named manifest.xml (case-sensitive!) and it must use the bundle tag as the top-level element of the XML structure. Furthermore the bundle opening tag needs to specify the format attribute which will determine the rules the rest of the XML tree has to follow.

Unless otherwise noted the entire manifest file is case-sensitive (including paths specified in it)!

v1.0.0

Inside the bundle element there have to be the assets, name and version elements. name is just the name of your plugin (arbitrary String) whereas version is the version of your plugin. Note that the version must be given in the format <major>.<minor>.<patch>.

Inside the assets element comes a list of one or more plugin elements. Each of these must specify the os and arch attributes for specifying the operating system and architecture respectively. The contents of these elements is the path to the corresponding plugin library inside the archive (relative to the manifest.xml file). Note that the paths must not start with ./ and as path separator a single forward slash is to be used (even on Windows).

The possible values for the os attribute are

and the possible values for the arch attribute are

Putting this together a sample manifest.xml can look like this:

<?xml version="1.0" encoding="UTF-8"?>
<bundle version="1.0.0">
  <assets>
    <plugin os="windows" arch="x86">myPlugin.dll</plugin>
    <plugin os="windows" arch="x64">sub/myPlugin.dll</plugin>
    <plugin os="linux" arch="x64">sub/libmyPlugin.so</plugin>
  </assets>
  <name>MyPlugin</name>
  <version>1.0.0</version>
</bundle>

Creating a plugin bundle

As written before, a plugin bundle essentially is just a zip file. The only restriction here is that it must not be created using the proprietary Deflate64 algorithm.

The steps to create a bundle file are as follows

1. Create an empty working directory
2. Copy the plugin libraries for the different OS and architectures into this directory (potentially in sub-directories)
3. Create a manifest.xml at the root of the working directory
4. Add all files and folders in your working directory (but not the working directory itself!) to a zip file
5. Change the file extension from .zip to .mumble_plugin

On Linux you can do this by using the zip command line tool like this:

zip my_plugin.mumble_plugin myPlugin.dll sub/myPlugin.dll sub/libmyPlugin.so manifest.xml

Notes

• You must not add any additional files to this archive. Keep the contents of the created archive strictly to the parts mentioned above. It might be tempting to treat the plugin bundle as a regular zip file that can be filled with arbitrary contents but this is not allowed! Instead consider the plugin bundle a binary of its own that has to follow a strict format as outlined above.
• Plugin names must not contain version numbers. At least not when they are distributed to end users. This is because Mumble assumes that the new version of a plugin will use a shared library with the exact same name as the old one. If this assumption is violated, the update mechanism will not work properly causing the new and the old version of the plugin to be installed in parallel.