The Add in Registry

Mono.Addins keeps all information about add-ins in a Registry. The add-in engine uses this registry to get information about existing add-ins and the extensions those implement. Queries on the add-in registry are fast and can be done without having to load the actual add-ins, saving time and memory in the host application. The add-ins are loaded only when objects instances or resources need to be loaded.

The location of the add-in registry can be specified when initializing the add-in engine. For example:

AddinManager.Initialize ("[ApplicationData]/MyApplication")

The path provided as parameter to Initialize can be:

• A relative or absolute path
• A path relative to a known system folder. Known system folders can be specified by enclosing them in brackets. So in the example, ApplicationData is going to be replaced by the value of Environment.SpecialFolder.ApplicationData.

The registry can be updated by an application by this call:

AddinManager.Registry.Update();

The registry has information about the location of every add-in and a timestamp of the last check, so the Update method will only scan new or modified add-ins. An application might add a call to AddinManager.Registry.Update() in the Main method to detect all new add-ins every time the app is started. Every add-in added to the registry is parsed and validated, and if there is any error it will be rejected.

The registry can also be updated by running the add-in setup tool (mautil).

Next topic: Addin Discovery