Notification framework

Instances sending notification messages need to know nothing about the instances that receive notification; this includes the type of receiver (instance or function), the receiver's protocol, the number of receivers, and how the receiver(s) respond to the notification.

The class of the sending instance, called the sender, defines classes that:

• Identify interests - the changes and events about which the sender notifies
• Convey the notification - the information about the change or event

The Notification framework is heavily used by the Compound Document framework and the View System. See Chapter 6, "Presentation and Compound Document framework concepts" and Chapter 4, "View System concepts" for details on how these other subsystems use notification.

Most of the notification classes depend only on the collection classes, and can be used at any level of the system where notification is appropriate.

In addition to learning about each of the primary Notification framework classes, after reading this section you will understand how to:

• Set up simple notification using the predefined classes
• Extend and customize the notification classes
• Use asynchronous notification
• Use notification between tasks

Notification concepts

Primary notification classes

Using simple notification

Sending custom notifications

Creating batched notifications

Using custom interests

Notification across task boundaries