Download 072908

Self-executing Java, J2EE
James Atlas
July 29, 2008
Review
• Software Testing
 Design process
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Announcements
• Final Exam
 08/15 at 3:30PM to 5:30PM in 107 Sharp Lab
(SHL107)
 We will have a review on 08/12, no class on
08/14
• Remaining topics
 Java Security
 3D graphics API + Sound
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Today
• Self-executing Java
• J2EE Intro
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Self-executing Java
• "How do I make an .EXE file from my Java
•
application?“
Many different approaches:




Executable Jars
Java Web Start
Custom launcher/wrapper
Ahead-Of-Time Compilers
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Executable Jars
• “zip” archive containing application code
•
and resources
contains a META-INF/MANIFEST.MF file
 Main-Class: MyAppMain
 Class-Path: mylib.jar
• automatically associated in Windows with
•
your installed JRE (javaw.exe)
requires a working, installed JRE
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Java Web Start
• From a web-link it automatically downloads
application to a local cache and launches it
• Less secure than Applets (with user
confirmation)
• Internet connectivity required
• Similar to:
java -classpath http://www.mysite.com/app/MyApp.jar
com.mysite.app.Main
• Example:
http://www.calcexp.com/weblaunch.htm
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Custom launcher/wrapper
• Creates a small native program that calls the
appropriate java commands
 Allows custom taskbar icons and splashscreens
 Can be configured to use a bundled JRE
• Launch4J - http://launch4j.sourceforge.net/
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Ahead-Of-Time Compilers
• Produces a conventional native executable for the
•
target platform
Pros:
 performance
 Intellectual Property
 No “warm-up” time
• Cons:
 limited tools depending on what version of Java
 very hard to do dynamic applications (custom
classloaders like web servers with JSP content)
 produces executable that is platform specific but
somewhat hardware agnostic
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Programming Assignment 5
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J2EE
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History
• Initially two tier architecture (client server
applications)
• Client is responsible for data access applying
business logic and presentation of data
• Only service provided by Server was that of
database server.
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Two Tier Application Architecture
Client
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Server
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Two Tier Application Architecture
• Drawbacks
- Easy to deploy but difficult to enchance or
upgrade.
- It makes reuse of business and presentation
logic difficult
- Not scalable and not suited for internet
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J2EE
• To develop N tier application
• It supports the development of a
variety of application types
 small client server systems
 Systems running on Intranets
 Systems on large scale internet ecommerce site
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J2EE Features
•
•
•
•
•
Component based model
Container provided services
Highly Scaleable
Simplified Architecture
Flexible security model
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Key J2EE APIs
• Component Technologies
 Servlets
 Java Server Pages (JSP)
 Enterprise Java Beans (EJB)
• Standard Services
 Java Database Connectivity (JDBC API)
 Java Naming and Directory Interface
(JNDI)
 Java Transaction API (JTA)
• Other Services
 HTTP, HTTPS, RMI-IIOP, JMS, JavaMail
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Containers in the N-Tier J2EE
Architecture
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J2EE Tiers
• Client Presentation
 HTML or Java applets deployed in Browser
 XML documentations transmitted through HTTP
 Java clients running in Client Java Virtual Machine
(JVM)
• Presentation Logic
 Servlets or JavaServer Pages running in web
server
• Application Logic
 Enterprise JavaBeans running in Server
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J2EE Application Model
• Browser is able to process HTML and
applets pages.
• It forwards requests to the web server, which
has JSPs and Servlets
• Servlets and JSPs may access EJB server.
• Java Standalone runs on java client, which
access EJB server using RMI.
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J2EE Application Model
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EJB – Enterprise Java Beans
• Enterprise Java Beans are components that are
•
deployed into containers
The container provides services
 Loading / Initialization
 Transactions
 Persistence
 Communication with EJB clients
 Enterprise Naming Context (JNDI name space)
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Anatomy of an EJB
• Remote Interface
 Methods that can be accessed by the outside world.
 Extends javax.ejb.EJBObject
• Remote Home Interface
 Life-cycle methods (create, findByPrimaryKey)
 Extends javax.ejb.EJBHome which extends
java.rmi.Remote
• Bean class
 The class performing the actual business process
 Implements an interface based on type of bean
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EJB – Enterprise Java Beans
• Entity Beans
• Session Beans
• Message Beans
 New in EJB 2.0
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Client / EJB Relationship
• How does a client application (Java class) utilize EJBs?
 Lookup - JNDI ENC
 Network protocol - RMI
 EJB container creates object with RemoteHome and Home
interfaces – this object passes calls to the bean class
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EJB – Enterprise Java Beans
• Entity Beans
• Session Beans
• Message Beans
 New in EJB 2.0
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EJB – Entity Beans
• Entity beans are classes that map to individual
entities – typically, an Entity bean references a row
in a database table, providing an object
representation of that database object.
 For example, an entity bean could represent a customer,
and changing the values in that entity bean would cause
updates to that database row
• Entity beans provide an abstraction layer so that
working with the entity is not specific to the storage
mechanism for that entity.
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Entity Beans - Persistence
• Container Managed Persistence (CMP)
 The EJB container automatically persists the EJB
objects, usually to a relational database where each type
of object is represented as a table, and each instance of
the object is a row in that table
• Bean Managed Persistence (BMP)
 The EJB container calls bean methods when it is
appropriate for the bean to load, save or update data,
enforcing transactions without transaction code written by
the bean developer
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EJB – Session Beans
• Session beans perform work for a client
application
 For example, a session bean could charge a
credit card for a specific transaction.
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Session Beans – State
• Stateful – A stateful bean maintains a
•
conversational state with a client. The client
perceives that it is only talking to one bean, and
that bean maintains information between calls
Stateless – A stateless bean maintains no client
information between method calls – the container
can substitute beans as necessary between
method calls
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EJB – Session Bean Example
package org.jboss.docs.interest;
import javax.ejb.EJBObject;
import java.rmi.RemoteException;
/** This interface defines the `Remote' interface for the `Interest' EJB. Its single method is the only
method exposed to the outside world. The class InterestBean implements the method. */
public interface Interest extends EJBObject
{
/** Calculates the compound interest on the sum `principle', with interest rate per period `rate'
over `periods' time periods. This method also prints a message to standard output; this is
picked up by the EJB server and logged. In this way we can demonstrate that the method is
actually being executed on the server, rather than the client. */
public double calculateCompoundInterest(double principle, double rate, double periods)
throws RemoteException;
}
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EJB – Session Bean Example
package org.jboss.docs.interest;
import java.io.Serializable;
import java.rmi.RemoteException;
import javax.ejb.CreateException;
import javax.ejb.EJBHome;
/** This interface defines the 'home' interface for the 'Interest' EJB. */
public interface InterestHome extends EJBHome
{
/** Creates an instance of the `InterestBean' class on the server, and returns a remote
reference to an Interest interface on the client. */
Interest create() throws RemoteException, CreateException;
}
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EJB – Session Bean Example
package org.jboss.docs.interest;
import java.rmi.RemoteException;
import javax.ejb.SessionBean;
import javax.ejb.SessionContext;
/** This class contains the implementation for the 'calculateCompoundInterest' method exposed by
this Bean. It includes empty method bodies for the methods prescribe by the SessionBean
interface; these don't need to do anything in this simple example. */
public class InterestBean implements SessionBean
{
public double calculateCompoundInterest(double principle, double rate, double periods)
{
System.out.println("Someone called `calculateCompoundInterest!'");
return principle * Math.pow(1+rate, periods) - principle;
}
public void ejbCreate() {}
public void ejbPostCreate() {}
public void ejbRemove() {}
public void ejbActivate() {}
public void ejbPassivate() {}
public void setSessionContext(SessionContext sc) {}
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}
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EJB – Session Bean Example
<?xml version="1.0" encoding="UTF-8"?>
<ejb-jar>
<description>JBoss Interest Sample Application</description>
<display-name>Interest EJB</display-name>
<enterprise-beans>
<session>
<ejb-name>Interest</ejb-name>
<home>org.jboss.docs.interest.InterestHome</home>
<remote>org.jboss.docs.interest.Interest</remote>
<ejb-class>org.jboss.docs.interest.InterestBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Bean</transaction-type>
</session>
</enterprise-beans>
</ejb-jar>
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EJB – Session Bean Example
package org.jboss.docs.interest;
import javax.naming.InitialContext;
import javax.rmi.PortableRemoteObject;
class InterestClient
{
/** This method does all the work. It creates an instance of the Interest EJB on the EJB server,
and calls its `calculateCompoundInterest()' method, then prints the result of the calculation. */
public static void main(String[] args)
{
try {
InitialContext jndiContext = new InitialContext();
ref = jndiContext.lookup("interest/Interest");
InterestHome home = (InterestHome) PortableRemoteObject.narrow(ref, InterestHome.class);
Interest interest = home.create(); //Create an Interest object from the Home interface
System.out.println(interest.calculateCompoundInterest(1000, 0.10, 2));
}
catch(Exception e)
{
System.out.println(e.toString());
}
}
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}
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EJB – Message Beans
• Message beans are classes that receive
asynchronous notification from a Java
Message Service server
 For example, a message bean could be
activated when vendor sends a purchase order
to a JMS queue.
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JMS – Java Message Service
JMS Queue
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JMS – Java Message Service
JMS Topic
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JMS – Java Message Service
• Why should I use JMS?
 Loosely-coupled systems
• Connectionless
• Removes dependence on client and server platform /
programming language / version
 Publish / Subscribe metaphor
• Send / receive information with many, unknown clients
 Integration with other messaging systems
• IBM MQ-Series
• Microsoft Message Queue
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Example EJB Application
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Servlets
• Are container managed web components
• Replace Common Gateway Interface(CGI) or
•
•
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Active Server Pages (ASP)
Generate dynamic response to requests from web
based clients
Synchronize multiple concurrent client request
Serve as client proxies
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JavaServer Pages (JSP)
• Text based documents describe how to
process a request and create a response
• Contains HTML or XML and other JSP
elements defined by JSP specification.
• Installed on web server
• Web components that sit on top of java
servlets
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J2EE Application Packaging
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JBoss
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What is JBoss
 Created in 1999, JBoss is the product of an
OpenSource developer community dedicated to
developing the best J2EE-compliant application
server in the market
 With 1000 developers worldwide and a steadily
growing number of downloads per month, reaching
72,000 for October ’01 (per independent
www.sourceforge.net), JBoss is arguably the most
downloaded application server in the world today
 Distributed under an LGPL license, JBoss is
absolutely FREE for use. No cost. Period.
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What is Application Server
 Application servers enable the development of
multi-tiered distributed applications. They are
also called “middleware”
 An application server acts as the interface
between the database(s), the web servers and
the client browsers
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JBoss- Application Server
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JBoss - example
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Project 2
• Need to setup group meeting time
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