Download Introduction to Software Components: the JavaBeans specs

Introduction to Software
Components: the JavaBeans
specs
Babak Esfandiari
Software Components
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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
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To be reusable, components:
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expose a public interface
behave according to explicit specifications
are oblivious to their clients
can be assembled graphically
JavaBeans
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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
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introspection
customization
events
properties
persistence
Introspection
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JavaBeans assembly tools such as the
BeanBox are able to discover Bean properties
and expose them using introspection
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the Java Reflection API is used
Beans must follow a certain number of coding
idioms
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default constructor
public methods
getters/setters
events
Customization
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once Bean properties are discovered, they can
be changed using introspection
it is possible to change the way properties are
accessed and modified
Events
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JavaBeans use the Java Event model
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EventObject class
EventListeners
Persistence
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Instantiated JavaBeans' states can be saved
and restored using serialization
long-term persistence achieved with XML