Introduction to Software Components: the JavaBeans specs Babak Esfandiari

Software Components Component: "Encapsulated software object that provides a certain functionality or service and can be used in conjunction with other components to build applications." one should be able to develop applications by selecting components from a catalog and compose them. the catalogs and the components might reside on remote hosts

Software Components To be reusable, components: – expose a public interface – behave according to explicit specifications – are oblivious to their clients – can be assembled graphically

JavaBeans Java's component model

JavaBeans Concepts “ A Java Bean is a reusable software component that can be manipulated visually in a builder tool” -> JDK1.1 introspection customization events properties persistence

Introspection JavaBeans assembly tools such as the BeanBox are able to discover Bean properties and expose them using introspection – the Java Reflection API is used – Beans must follow a certain number of coding idioms default constructor public methods getters/setters events

Customization once Bean properties are discovered, they can be changed using introspection it is possible to change the way properties are accessed and modified

Events JavaBeans use the Java Event model – EventObject class – EventListeners

Persistence Instantiated JavaBeans' states can be saved and restored using serialization long-term persistence achieved with XML