Creating Modular Struts2 Applications with AppFuse and Netbeans – A Tutorial

Introduction

I am not in the habit of writing tutorials but I found that there was a very small niche that I couldn't find adequate documentation for so I decided to write this tutorial. I recently created a new application in which I used the excellent Struts 2 framework. I used Hibernate for persistence and Spring for dependency injection. I used Sitemesh to decorate the user interface and Freemarker to create the forms.

At first the list of technologies was overwhelming and I spent more than a month trying to figure out how to get all these to work well with each other. When I came across Matt Raible's most excellent framework AppFuse it was a Godsend. AppFuse can get you up and running in a few minutes with a large number of configurations.

I found that I was able to create projects without worrying about the configuration and then customize to suit my own needs. The documentation for AppFuse is very good and most of what I write here is covered. Its just that in using Netbeans there are a few points that I had to look in the mailing list for. So its only a very small bit I have to add. You will find appfuse quickstart at http://appfuse.org/display/APF/AppFuse+QuickStart.

Setting Up the Environment

First, lets make sure that we have everything installed and configured. You will need:

1. Netbeans 6.1 – http://www.netbeans.org

2. MySQL 5 - http://www.sun.com/software/products/mysql/getit.jsp

3. Java 6 – http://java.sun.com

4. Maven 2.0.7 at least - http://maven.apache.org/

On the respective websites there are installation instructions so I will not repeat them here. However there are a few things that I would mention.

Netbeans

After Netbeans has been installed you may install the Maven plugin.

Start by opening the Plugins window. Click Tools > Plugins. In the plugins window you can update existing plugins or install new plugins. Click on the Available Plugins tab. You will see the list of plugins that are available for download. See Figure 1.

Figure 1: Available Plugins in Netbeans

Search for the Maven pluigin and select it then click Install.

After the installation Netbeans is now Maven Aware.

Maven Local Repository

Create a local repository for Maven so that the project could be built even without an Internet connection. Select a location on the hard drive and set the following in the M2_HOME/conf/settings.xml file:

<localrepository>path/to/your /local/repository</localrepository>

Creating the Application

Now its time to create a new application, and this is where the magic of AppFuse happens. As the title implies this project is using Struts2 Modular architecture. AppFuse allows many different configurations so you should visit the website and see for yourself.

1. Open a command window and run the following command.

mvn archetype:create -DarchetypeGroupId=org.appfuse.archetypes -DarchetypeArtifactId=appfuse-modular-struts -DremoteRepositories=http://static.appfuse.org/releases -DarchetypeVersion=2.0.2 -DgroupId=com.mycompany.app -DartifactId=myproject

Make sure you change com.mycompany.app to your own package structure and myproject to the name of your project. Maven creates a directory with your project name.

2. CD into the newly created project directory

In here you will find a file called pom.xml. This file is the main configuration file for Maven. Open it and edit the Database Settings. You will find these near the bottom of the file. Add the user name and password necessary for your database.

3. Run mvn

This downloads all the files and dependencies from the internet for you. It may take a long time to run. The database will be created in MySQL at this point.

4. Run mvn war:inplace

This will copy the source code from the appfuse wars into your src directory and give you a chance to make changes to them.

5. Run mvn appfuse:full-source -DrenamePackages=false

This is necessary for Netbeans to find the dependent classes. It basically installs all the source code into your application. The rename packages option is necessary if you want to keep the appfuse packages separate from your packages.

6. Now lets test your project and make sure its working. CD to the web directory of your project. Run mvn jetty:run-war.

This builds your website and starts the Jetty server. You can now open your browser and visit http://localhost:8080 to see your application. The default user name and password is admin/admin.

7. Now you can open Netbeans and click File > Open Project. Browse to the location of your new project and click on it. Make sure that you select the Open Required Projects checkbox. Click Open Project button.

Now edit your project to your hearts content.

How we learn

We continue learning all the days of our lives. Or so I heard. Now, I want to avoid getting too technical and talking about short term and long term memory and cognition and so on. But in short, short term memory, or task memory, has to do with the current task that we are engaged in. For instance, if you are cooking dinner, then the items in your short term memory has something to do with cooking. Since short term memory is limited, people tend to perform badly when there are more than one tasks occupying their short term memory. Hence, multitasking is hard.

Long term memory contains the things that we actually learn. For example, your address, how to tie your shoes, how to drive and so on. Most of us cannot remember what we ate for breakfast on the third of April 1987. That is because, that fact was not important enough to make it into our long term memory.

The trick is getting the things we need to know into our long term memory. Apparently, our brains are selective about what gets into the long term memory. So I may want to learn how to use the JPA and Hibernate and Spring and Struts 2 and a myriad other frameworks, API's and tools but my brain may decide that its not important enough to remember. Instead, I could quote word for word every line from the Lord of The Rings. Why?

Recently I started attempting to use Appfuse to create a new project that I am about to build. Since I am already experienced with Hibernate, Struts 1.x and some of the other technologies involved I thought that I would breeze through the learning phase. That was not that case. After examining why it was so difficult for me to learn this framework I realized that I never gave myself the chance to learn. I approached the task of learning with arrogance. Believing that I already knew enough.

Arrogance closed the door to learning. So I tried a series of ten minute approaches and none worked and my frustration grew and I blamed Appfuse for being too complex.

Then one day I spent several hours working on Struts 2 alone. I found it quite easy to pick up and learn. I stopped, rested did no more learning that day.

The next day I spent several hours on sitemesh. Again, quite easy to learn and use. I then spent some hours each on Freemarker, Maven and Spring. At the end I tried Appfuse again and found it quite easy to use. In fact I wonder how I ever got anything done before.

The lessons I learned is that first, don't be arrogant about your knowledge. There is always more to learn. And second, give yourself a chance to learn. That is, make time to spend on the topic, make sure you don't crowd too many different new things into the same day. Your brain needs time to convert the things you experience into long term memory.