JBoss at Work JAW Motors Application Chapter 1-3 by fsy40675

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									   JBoss at Work
JAW Motors Application
    Chapter 1-3
      Jeff Schmitt
     October 9, 2006
      JAW Motors Application
• Fictitious automobile dealership
• Each chapter progressively adds a new J2EE
  technology that solves a specific business problem
• Viewing cars – JSP
• Storing cars (persistence) – JDBC or Hibernate
• Credit check -- JMS message and JavaMail
  response
• Purchasing – transactional support using Stateless
  Session Beans
• Sharing data between dealerships – Web Services
    JBoss – Application server
• Compiled Java code runs inside JVM
• Java classes need a container to provide an
  infrastructure, a framework to handle low-level
  details
• An application server is a loosely coupled
  collection of containers (or "services") that
  correspond to the various parts of the J2EE API.
• JBoss is an open-source J2EE 1.4 standards
  compliant application server
   Java Management Extensions
             JMX
• JBoss is a thin JMX (Java Management
  Extensions) microkernel
• JMX is a framework that allows you to interact
  with live, running code
  – Start and stop services
  – Gather metrics
  – Change parameters
• Services that implement the JMX interface are
  called Managed beans or Mbeans
  – MBeans that run inside JBoss include: Log4J,
    Tomcat, Hibernate
            Tools needed
• Java JDK – J2SE 1.4 or higher
• Ant – to compile, package and deploy
  Java code
• XDoclet – to generate deployment
  descriptors, web.xml and various other
  J2EE configuration files.
• XDoclet is a combination of custom Ant
  tasks and special attributes that you
  include in your source code.
      JAW Motors Application
• Use Tomcat servlet container
• JBoss is an application server, but includes
  Tomcat
• 3-tier application
  – Presentation – JSP and servlets
  – Business logic – EJB and MDB’s
  – Persistence – relational database
• Components in each tier
  – Highly cohesive – components do only one thing
  – Loosely coupled – components have no dependences
    across tiers
        Model View Controller
• View – HTML, JSP, CSS and JSTL produce the
  screen contents
• Model – POJO (Plain Old Java Objects), Java
  Beans
• Controller – mediates communication between
  the view and the model -- a servlet
• Framework – many design decisions already
  made for you – this book is framework-neutral –
  uses its own controller servlet
                    View
• carList.html
• carList-jstl.jsp – with JSTL tags – JSP
  scriplet defines data: carList[]
• carList.jsp – with stylesheet: default.css –
  data saved in pageContext
          Model and Controller
• Model
  – CarBean is a POJO, is a JavaBean
  – carList.jsp uses JSP EL
• Controller
  – ControllerServlet
  – Action parameter indicates page indirectly
  – To access carList.jsp we use: <a
    href=“controller?action=viewCarList”>
  – Controller translates action=viewCarList to access
    carList.jsp
           JBoss Deployment
• Applicatioin Assembly
  – Web Archive file – a collection of presentation tier
    files (HTML, JSP, Servlets, etc)
  – EAR – Enterprise Archive (EJB’s)
  – SAR – Service Archive (Web Services)
  – Use “jar” command to bundle them into a single file
• Application Deployment
  – Hot deployment -- While JBoss is running, copy the
    WAR, EAR or SAR file to
    $JBOSS_HOME/server/default/deploy/
  – Cold deployment – stop JBoss, copy the file, restart
    JBoss – this is the recommended deployment
                EAR Deployment
•   EAR – Enterprise Archive
•   Similar to WAR – Web Archive
•   bundles together the pieces of a full J2EE application
•   keeps things organized
•   unpacked by server
•   Contains three “modules”
    – Web Module – a war file for presentation
    – EJB Module – an EJB jar file
    – Java Module – Java classes jar file
• Application.xml – in META-INF directory -- a packing list
  – tells where you can find each file relative to the root
     Data Access Object - DAO
• A layer of abstraction
• Hides the actual persistence details behind a common
  interface
• For this chapter, a simple ArrayList
• In subsequest chapters, Hibernate, an Object-Relational
  Mapper (ORM) for relational DB
• CarDAO.java
   – Constructor creates ArrayList of CarDTO objects
   – findAll() – method to return all cars
• CarDTO.java – a Car JavaBean
• ControllerServlet.java – creates CarDAO and forwards to
  carList.jap
        Automated Deployment
• Ant can
  –   compile and create WAR/EAR (build process)
  –   Create/delete directories
  –   Copy files
  –   Call XDoclet tasks
• XDoclet – to generate config files (web.xml)
  and/or java code during the build process
• Cold deploy uses Ant task: cleandeploy
• Visit http://localhost:8080/jaw

								
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