VisualAge beans are Java classes that conform to the JavaBeans component architecture. Composite beans are made up of embedded beans. We use the term bean to refer to both a class and its instances, as follows:
During visual composition, you interact with bean interfaces. The most useful bean interfaces contain the following features:
Access to data, or properties. A complete property interface includes methods to return the value of the property, to set the value of the property, and to notify other beans when the value of the property changes. The interface for a property does not have to be complete. For example, a property might be read-only, in which case the interface would not support the ability to set the value of a property. A property can be any of the following:
Access to the behavior of a bean, or methods. These represent tasks you can ask a bean to perform, such as open a window or add an object to a collection of objects.
Event notification. By signaling events, a bean can notify other beans that its state has changed. For example, a push button can signal an event to notify other objects when it is clicked, or a window can signal an event when it is opened, or a bank account can signal an event when the balance becomes negative.
Events can also be signaled when the value of a bean property changes, such as when money is deposited into or withdrawn from a bank account. In this case, the balance property is said to be bound to an event.
Visual Programming Fundamentals
Visual Composition Editor Overview
Bean Design for Visual Composition
Factory and Variable Beans