What is a Notification?
A notification is a message from the database that an object has changed.
Messages are sent to applications or forms that subscribe to receive them.
What Kinds of Events are Notified?
Standard events are the creation, deletion or updating of an object.
You can even define a specific change to be notified about.
What Happens When a Notification is Received?
A notification event is handled in a similar way to a standard Windows event
(such as a mouse click on a button).
You write a method that is executed when the notification is received.
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How You Will Use Notifications
You have seen how JADE uses notifications to refresh a list box.
You will use notifications to reserve a book.
You will paint a form, which has a list box to list all books
in the library and a status line to display messages.
A book is 'reserved' by selecting it from the list box.
Notifications of changes to the book are started.
When a notification is received, the method finds out if the book was checked out
or in, and displays a message.
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