The NBM File

Modules that you want to make available as an update are distributed in the form of NBM files. These consist of a JAR archive containing the actual module together with its configuration data and update information required by the Plugin Manager (see Figure 36-2). An NBM file may also contain the libraries required by the module. The content of the module JAR file and its related configuration files have already been described in Chapter 3.

One file I have not yet discussed is the info.xml file. This file contains information displayed to the user when choosing existing modules or modules to be installed in the Plugin Manager (see Listing 36-1). The manifest element contains information from the module's manifest file. For example, the defined dependencies are very important. If the user chooses a module in the Plugin Manager that is dependent on another module, the latter is automatically activated so it can be downloaded simultaneously with the selected module. If dependencies cannot be satisfied, the user can install the module without being able to activate it, though. Finally, you can also add license information via the license element, which was displayed to the user before installation of the module began. This forces the user to confirm that licensing requirements have been satisfied so the module can be installed.