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: –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