Transcript Seminarium on Component-based Software Engineering

Seminarium on
Component-based
Software Engineering
JavaBeans
David Snuijf
Java
 Released in alpha-form in 1995 by
Sun
 Originality: concepts of applets
 Java became common used by 1996
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Java – components
 Java component models:
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Applet
JavaBeans
Enterprise JavaBeans
Servlets
Application client components
J2SE
J2EE
J2SE: Java 2 platform, Standard Edition
J2EE: Java 2 platform, Enterprise Edition
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Let’s get into
avaBeans
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JavaBeans – solution to..
 Enables software developers to
design and create reusable pieces of
software that easily integrate
 with each other
 with applications
 with development tools
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JavaBeans – Main aspects
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Events
Properties
Introspection
Customization
Persistence
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JavaBeans
 Approach to composition:
 Connection-oriented programming / wiring
 Beans define:
 Event sources
 Event listeners
 By connecting one bean instance’s
listener to another bean instance’s
event source, events flow
 container structures
 InfoBus
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Let’s get into
nterprise JavaBeans
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Enterprise JavaBeans (EJB)
 Provide a framework for components
that may be "plugged in" to a server
 Enterprise JavaBeans is totally
different of JavaBeans, except that it
uses some similar concepts
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Enterprise JavaBeans – Goals
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Easy for developers to create applications
Standard way for client/server applications
Compatible with and uses other Java APIs
EJB can interoperate with non-Java apps
EJB is compatible with CORBA
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Enterprise JavaBean component
Client
EJB Server
EJB Container
Home
Remote
or local
EJB Home
stub
EJB Object
stub
Home
EJB Home
Remote
or local
EJB Object
EJB Bean
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Kind of Enterprise JavaBeans
Four kind of EJB beans
 Stateless session
 Stateful session
 Entity
 Message-driven
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Questions?
?
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