BZFS can be built to support the loading of external libraries as plug-ins. These plug-ins can alter or replace the logic applied by the server, as well as automate many common tasks.
Plug-ins are a simpler way to apply modifications to the game, as they do not require the server owner to modify or recompile his/her BZFS application. By using the BZFS API plug-ins are also able to be mixed and matched in an easy way.
Plug-ins are compile dynamic link libraries, that are built for the same OS/RuntimeEnvironment as the BZFS server that hosts them. On Microsoft Windows they are built as DLL files. On Linux and other Unix-like systems they are built as .so files.
Plug-ins are loaded at startup by the -loadplugin option, or at run time with the /loadplugin command. If the full path to the plug-in is not specified, then BZFS will search a number of known sub directories for the plug-in as it attempts to load it. Using a valid path to the plug-in on load is highly recommended.
Some plug-ins take parameters that are passed to the plug-in on load. This is often a numeric value, or a path to a file. To pass a parameter to a plug-in, simply add a ',' after the plug-in name or path, and then add the parameter. Parameters can not have spaces, due to the way BZFS parses command line options and / commands.
On load, plug-ins install a number of callbacks and event handlers with the hosting BZFS that are called when specific events happen. This allows the plug-in to perform additional actions on these events, or if need be, alter the results of the default logic of the server.
Third Party Plug-ins
A number of non-developers have created plug-ins for BZFS, and usually release them on the BZFlag Forums.