Node Classes

Node classes are descriptions of nodes. From the application's (and user's) point of view, classes are abstractions that have only three features:

• They have a name. This name is stored in the MIDI driver itself, and can be used by applications or the user to identify the class. However, the driver itself uses numbers to identify classes, so the applications (or the user) must provide a mapping from class names to class numbers.

• They can be instantiated. A node instance of that class is then created. See Node Instances for the features of a node instance.

• They define the interpretation of the compound message. The architecture itself doesn't care about the contents of the compound messages. This is the responsibility of the classes. The compound message format described above is the one used by all the pre-defined classes. It is possible to create a collection of classes which uses a different format, provided the size of the structure is the same.

Generally, all instances of a particular class perform the same function, but this is not a requirement. If a class supports it, the application can send data to a particular instance of that class at any time. This data can be used to configure (or reconfigure) the instance, possibly giving it completely different functionality.