Oracle9iAS Containers for J2EE Servlet Developer’s Guide Release 2 (9.0.2) January 2002 Part No. A95878-01 Oracle9iAS Containers for J2EE Servlet Developer’s Guide, Release 2 (9.0.2) Part No. A95878-01 Copyright © 2002 Oracle Corporation. All rights reserved. Primary Authors: Brian Wright, Tim Smith Contributors: Jasen Minton, Joyce Yang, Sunil Kunisetty, Bryan Atsatt, Ashok Banerjee, Charlie Shapiro, Philippe Le Mouel, Paolo Ramasso, Olaf Heimburger, Sheryl Maring, Mike Sanko, Ellen Barnes The Programs (which include both the software and documentation) contain proprietary information of Oracle Corporation; they are provided under a license agreement containing restrictions on use and disclosure and are also protected by copyright, patent and other intellectual and industrial property laws. 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Contents Send Us Your Comments .................................................................................................................. vii Preface............................................................................................................................................................ ix Intended Audience ................................................................................................................................. x Documentation Accessibility ................................................................................................................ x Organization ........................................................................................................................................... xi Related Documentation ........................................................................................................................ xi Conventions.......................................................................................................................................... xiv 1 Servlet Overview Information Sources........................................................................................................................... 1-2 Servlet Information....................................................................................................................... 1-2 Additional OC4J Documents ...................................................................................................... 1-2 Introduction to Servlets..................................................................................................................... 1-3 Advantages of Servlets ................................................................................................................ 1-3 Servlets and the Servlet Container ............................................................................................. 1-4 Request Objects, Response Objects, and Filters ....................................................................... 1-5 Session Tracking ........................................................................................................................... 1-6 A First Servlet Example ..................................................................................................................... 1-7 Hello World Code......................................................................................................................... 1-7 Compiling and Deploying the Servlet....................................................................................... 1-8 Running the Servlet...................................................................................................................... 1-9 iii 2 Servlet Development Servlet Development Basics ............................................................................................................. 2-2 Code Template .............................................................................................................................. 2-2 Servlet Lifecycle ............................................................................................................................ 2-3 Servlet Behavior ............................................................................................................................ 2-3 Invoking a Servlet............................................................................................................................... 2-5 Action by the Servlet Container Upon Request ....................................................................... 2-5 Invoking a Servlet by Class Name in OC4J............................................................................... 2-6 Configuration for Servlet Invocation in a Deployment Environment .................................. 2-7 Servlet Loading and Initialization................................................................................................... 2-9 Servlet Sessions................................................................................................................................. 2-10 Session Tracking ......................................................................................................................... 2-10 Session Cancellation ................................................................................................................... 2-11 Session Servlet Example ............................................................................................................ 2-12 Session Replication ..................................................................................................................... 2-15 Use of JDBC in Servlets................................................................................................................... 2-17 Database Query Servlet.............................................................................................................. 2-17 Deployment and Testing of the Database Query Servlet...................................................... 2-20 EJB Calls from Servlets .................................................................................................................... 2-23 Local EJB Lookup Within the Same Application ................................................................... 2-23 Remote EJB Lookup Within the Same Application ............................................................... 2-31 EJB Lookup Outside the Application....................................................................................... 2-31 3 Deployment and Configuration Introduction to Web Application Deployment and Configuration .......................................... 3-2 Web Application Modules........................................................................................................... 3-2 Overview of OC4J Deployment.................................................................................................. 3-3 Overview of Web Configuration Files....................................................................................... 3-3 Application Assembly ....................................................................................................................... 3-6 Application Directory Structure ................................................................................................. 3-6 Application Build Mechanisms .................................................................................................. 3-7 Application Deployment..................................................................................................................