How Do I use Jakarta Struts with Oracle9i
JDeveloper?
An Oracle JDeveloper How To Document
May 2002
Note: This document is specifically for version 9.0.2. Later versions of JDeveloper
have built-in Struts integration.
For the latest on integration between Struts and Oracle JDeveloper 10g see
these resources:
Introduction
to Oracle JDeveloper10g and Struts
Online
Demo Struts basics in JDeveloper
Content
Introduction
This TechNote describes in detail how to configure and use Jakarta Struts with
Oracle9i JDeveloper
Production version 902. It describes how to download, install and run Struts
examples applications inside of JDeveloper. It explains how to deploy a Struts
application and it also provides a product sneak preview of the upcoming integrated
Struts features in our next maintenance release of Oracle9i
JDeveloper .
What is Struts?
Struts is an open source framework for building Web applications that integrates
with J2EE technologies like Java Servlets, JavaServer Pages and JavaBeans. Struts
enables Web application development which follow the Model-View-Controller (MVC)
design paradigm.
MVC, also known as Model 2, is an application architecture which is
divided into the following components:
- Model - This is the data model which is usually developed by the end user
of the Struts framework. This is typically the application's business logic
and code to interact with a database.
- View - In a generic sense, the View is comprised of the components which
make up the application's user interface. Struts utilizes JSPs to serve as
the view.
- Controller - This is the program control logic which accepts user input
and decides how to respond. The response is generated via the View components.
Struts provides a front-end servlet which acts as a main application Web request
dispatcher.
Struts Components
The Struts framework is made up of the following components:
- The Action (Controller) servlet - Struts provides a ready to use servlet
which receives application web requests and dispatches them to the different
application components.
- A set of JSP Tag libraries - Struts provides a set of useful tag libraries
which perform varied tasks from HTML generation to application logic.
- Example Applications - In order to make Struts easier to understand, several
example applications are provided with the framework ready to run.
- A Struts runtime library - The Struts runtime library contains the necessary
libraries needed to run a Struts application. This file is deployed along
with a completed Struts application.
- Documentation - Struts provides a complete set of documentation in the framework.
A typical Struts application
The following diagram describes a very simple Struts application.
Figure 1. A Simple Struts Application
Figure 1 depicts a simplified Struts application. The application's Control
program is the Struts Action servlet. It receives application Web requests and
dispatches them to the various View components based on a set of rules defined
in the Struts-config.xml file. The View components are comprised of JSPs using
the the Struts custom tags as well as non JSP components such as an Action Class
and a Form Class. The Action class can validate content submitted from an HTML
form. The Form class is a Java representation of every field defined in the
HTML form. The Action class actually uses the Form class (also referred to as
Form Bean) to validate the contents of the form. To provide data to the application,
a component or set of components allow for the interaction of the data Model
and the application's View.
Using Struts in Oracle9i
JDeveloper
Using Struts in JDeveloper is actually quite easy. The following steps show
how to begin working with Struts within JDeveloper.
Step1: Download Struts
To obtain the latest copy of the Struts framework, go to: http://jakarta.apache.org/struts/.
Locate the latest "release build" of Struts. At this time it is currently
version 1.0.2. The entire framework is packaged into a single zip file. Unzip
this file into a local area: d:\struts. As we unzip the archive we see the following
directories:
- lib - This directory contains the struts runtime library, struts.jar as
well as the Struts custom tag libraries.
- webapps - This directory contains the vaiorus example applications archived
in J2EE WAR archives. A documentation application is also provided.
Once you've download and unzipped the struts archive you're ready to begin
using Struts.
Step2: Install and Run the Struts Example Application
The next in getting familiar with using Struts with JDeveloper is to install
and run the Struts "Example Application". The Struts "Example
Application" provides a working example of a complete Struts application.
By loading it into JDeveloper and observing how it runs, you will be able to
quickly learn how a Struts application works. In this step you will use the
"Create Project from existing WAR" feature to load the example application
into a JDeveloper project.
Locate the "Create Project from existing WAR" wizard in the gallery
and invoke it.
Figure 2. Creating a Project from an existing WAR
As the wizard appears it will allow you to locate the Struts Example application
WAR file load it as a JDeveloper project.
Figure 3. Specifying the location of the Struts example application.
It also allows you to define the location of your Web Module. This is the root
directory where the files will be placed. In this example I've chosen to place
them in subdirectory under my project directory.
After the wizard completes it's task, you will have a new project loaded with
Struts Example Application files.
Figure 4. The Struts Example Application loaded into JDeveloper
In figure 4 we see the example applications inside of a JDeveloper project.
Notice that I changed the Struts example project to display in "Category"
view. This is changeable on the JDeveloper navigator toolbar. (highlighted in
red)
After successfully loading the application into JDeveloper, the next step
is to run it!
Before running the application, you must add the Struts.jar runtime library
as well as the Oracle XML parser library. This is done by editing the project
properties by double-clicking on the project in the navigator. To add a new
library for the Struts runtime click on New and define the location of the struts.jar
library. Then make sure to add the library to the project. Now add the Oracle
XML parser library to the project as well.
Figure 5. Configuring the Struts Example Project Libraries
Once the libraries have been added, you can successfully compile and run the
example application! To run, simply select the file index.jsp in the
navigator and select "Run index.jsp" from the context menu. This will
launch the embedded OC4J and start the application.
Figure 6. Running the Example Application in JDeveloper
The example application contains a running example of how to use the various
custom tag libraries as well as how to define the application mappings in the
Struts-config.xml file. The Struts-config.xml file is located in the WEB-INF/lib
node in the JDeveloper navigator. Also notice that this application provides
a "Walking Tour of the Example Application" link. By clicking on this
link, you will be able to see a live tour of each of the elements of the application
and see how they work.
Once you've spent some time in discovering how the example application works,
it is now time to start building your own Struts applications. Fortunately the
Struts framework provides a blank application to get started.
Step2: Install and Run the Struts Blank Application
The Struts "Blank" application provides a complete starter application
which you can then modify. Specifically it contains a starter JSP page, an example
application resource file as well as an example struts-config.xml file.
Installing the Struts "Blank" application is just as easy as installing
the "Example" application. We simply use the "Create Project
from existing WAR" again and select the "Struts-Blank.war" file
instead. You must also remember to add the struts.jar library as well.
Deploying a Struts Application
Since a Struts application is really just a J2EE Web application, it can easily
be packaged into a Web Archive (WAR) file and loaded onto any J2EE compliant
application server. Assembling a WAR file for your Struts application is quite
easy. Simply invoke the Create WAR, deployment profile from the JDeveloper Gallery
and accept all of the defaults in the wizard. This will create a new deployment
profile and add it to your project. A nice thing to notice is that the Struts
runtime jar file is automatically packaged into the WAR file so any further
configuration of the deployment server is not needed!
Figure 7. Packaging your Struts Application as a WAR file.
Once the deployment profile is created, you can either deploy the application
to an actual WAR file which could be transferred to a J2EE application server
or you could deploy it directly to Oracle9i
Application Server.
Upcoming Struts Features in Oracle9i JDeveloper !
The next maintenance release of Oracle9i JDeveloper will contain several new
powerful features to further enable Struts development.
These include:
- Embedded Struts Framework - The Struts framework will be installed into
JDeveloper by default. No longer need to download and install manually.
- Pre-Loaded Struts Tag Libraries - The Struts Tag Libraries will be pre-loaded
onto the Component Palette.
- Struts Configuration Wizard - A simple to use wizard to enable editing of
the struts-config.xml file.
- Struts Application Wizard - Turns your existing project into a Struts enabled
project.
- Struts Action Class Wizard - Generates Java starter code for a Struts Action
class.
- Struts Form Bean Wizard - Generates Java starter code for a Struts Form
bean.
- BC4J JSP Struts Application Wizard - Generates a fully functional Business
Component for Java JSP application.
Summary
Struts now provides a common methodology for assembling enterprise J2EE Web
applications where there was none in the past. Web application developers are
finding themselves adopting the Struts application development framework and
methodology instead of devising their own. Oracle9i JDeveloper understands the
need for a framework methodology will continue to enhance Struts developer's
capabilities and productivity by offering more and more productivity enhanced
Struts development features.
References
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