Getting Started with Tomcat - Part 1

by Dr. Wenjie He

Apache Tomcat is a very popular light-weight Java HTTP web server for Java-based web application development. It is an implementation of the Java Servlet and JavaServer Pages technologies. In this class, we are going to develop all of our web applications on Tomcat.

Apache Tomcat Versions

Servlet/JSP Spec	Apache Tomcat version
2.5/2.1	6.0.18
2.4/2.0	5.5.26
2.3/1.2	4.1.37
2.2/1.1	3.3.2

Preparing for Software Installation

In this class, we are going to install many software packages on our computers. In order to manage our software well, I suggest a single tree directory structure to organize all the software packages used in this class, that is, all the software packages installed for this class are in the folder C:\JavaEE. Based on the functionalities, we organize the software in the following categories:

1. C:\JavaEE\DBMS     for the database management systems
2. C:\JavaEE\IDEs     for the Java Integrated Development Environment (IDE) tools
3. C:\JavaEE\JDKs     for different versions of the Java JDKs (or Java SEs)
4. C:\JavaEE\Servers     for the application servers and Web servers
5. C:\JavaEE\Tools     for miscellaneous application development tools and libraries

Note: This file structure is optional. You can use whatever file structure you like. But if we use the same file structure for the whole class, it will make our life much easier for this class, especially when we develop projects in collaboration.

Installing Java SE (or JDK)

Download the current version of Java SE

1. Go to the Sun Java Download web page http://java.sun.com/javase/downloads/ea.jsp, and click the link JDK 6 Update 10 RC. Download the version for your operating system.
2. Create the folder C:\JavaEE\JDKs if you have not done so and you decide to use the above mentioned file structure.
3. Run the executable file.
4. You may need to change the default installation directory of the JDK as in the video clip ( play ).
5. Similarly, you may need to change the default installation directory of the JRE as in the video clip ( play ).

I. Installing Apache Tomcat Server

Download Tomcat 

Go to the Apache Tomcat web page http://tomcat.apache.org. Before we download, we need to decide which version of Tomcat we should download. The current version of Tomcat is 6.0.18. If you go to the Tomcat 6.0.18 download page, you would see

If you compare it with the Tomcat 5.5.26, you can notice the difference.

The Administration Web Application is missing in the Tomcat 6, and we are going to use the administration tool to configure the rescourses in our web applications. Therefore, we should choose Tomcat 5 for this class.

Under the 5.5.26 bar, download the following two files,

1. Click the zip link under the Core bullet to download the file apache-tomcat-5.5.26.zip. If this link does not work, you can go to http://archive.apache.org/dist/tomcat/tomcat-5/v5.5.26/bin/ to download the file apache-tomcat-5.5.26.zip. For different operating system, you need to pick different versions.
2. Click the zip link under the Administration Web Application bullet to download the file apache-tomcat-5.5.26-admin.zip. If this link does not work, you can go to http://archive.apache.org/dist/tomcat/tomcat-5/v5.5.26/bin/ to download the file apache-tomcat-5.5.26-admin.zip.

Install Tomcat 

Installation of Tomcat is very simple. You simply unzip the two files downloaded above and extract them to appropriate folders. (There is a Windows Service Installer version of Tomcat that is an executable file.)

1. Create a new directory Tomcat inside C:\JavaEE\Servers\Tomcat that will be used to contain all versions of Tomcat (recommended but not required).
2. Unzip the file apache-tomcat-5.5.26.zip and extract all the files into the folder C:\JavaEE\Servers\Tomcat (recommended but not required). Watch the video clip (play ) for more detail.
3. Unzip the file apache-tomcat-5.5.26-admin.zip and extract all the files into the folder C:\JavaEE\Servers\Tomcat (recommended but not required). During the installation, you can overwrite all the files with the same names. Watch the video clip (play ) for more detail.

II. Setting Environment Variables for Tomcat

Before we set the environment variables, locate the JDK installation directory and the Tomcat installation directory. In this tutorial, we collect the information in the following table,

Installation Directory of JDK	Installation Directory of Tomcat
C:\JavaEE\JDKs\jdk-6u10	C:\JavaEE\Servers\Tomcat\apache-tomcat-5.5.26

Set the environment variables as in the following table

Note: If your installation directory of JDK or Tomcat is different from ours listed in the table above, you should change the values accordingly in the following table.

Variable Name	Variable Value
JAVA_HOME	C:\JavaEE\JDKs\jdk-6u10
CATALINA_BASE	C:\JavaEE\Servers\Tomcat\apache-tomcat-5.5.26
CATALINA_HOME	C:\JavaEE\Servers\Tomcat\apache-tomcat-5.5.26
CATALINA_TMPDIR	C:\JavaEE\Servers\Tomcat\apache-tomcat-5.5.26\temp

1. In your Window, click Start ⇒ Control Panel. In the Control Panel window, double-click the System icon and select the Advanced tab.
2. Click the Environment Variables button, the window of the Environment Variables opens.
      
3. Click the New button in the top half, and type JAVA_HOME as the variable name and C:\JavaEE\JDKs\jdk-6u10 as the variable value. Click OK.
Windows Vista Users:
You should set JAVA_HOME at the System variables area, the bottom half of the Environment Variables window. Otherwise, it would not work.
4. Similarly, set the other environment variables in the table. Watch the video clip (play ) for more detail.

Question: After you set the environment variables, do you need to restart the computer to make the change take effect?

III. Running Tomcat

1. Open a command window, cd to your C:\JavaEE\Servers\Tomcat\apache-tomcat-5.5.26\bin directory. (If your Tomcat installation directory is different from ours here, do the change accordingly.)
2. Type the command

   startup

   at the command line. If a window pops up to ask you if you unblock the program, click the unblock button.
3. Open a Web browser, and visit the URL http://localhost:8080. You would see the Tomcat welcome page as follows. Watch the video clip (play ) for more detail.
4. Compare Welcome Pages of Tomcat 5 and 6


See any difference? Where is the Tomcat Administration link in the Tomcat 6 welcome page? We definitely need it.
Question: Is there any difference if we use the FireFox browser instead of the Internet Explorer?
5. Stop Tomcat
   In the same window that you started Tomcat, type the command

   shutdown

IV. Running Web Application in Tomcat

Get the example

Download the example Duke.zip. After you unzip it, you get the Duke folder. This example is from the Sun's Java EE 5 Tutorial. You can find the example by

1. Go to http://java.sun.com/javaee/5/docs/tutorial/doc/gfiud.html and click the Download link. You can find the file javaee-5-doc-tutorial-1.0_04.zip after a few clicks. Download it.
2. Extract the files in javaee-5-doc-tutorial-1.0_04.zip to a folder you choose. You would see the folder javaeetutorial5. The example is in javaeetutorial5\examples\web\hello1.
3. Since the original example is developed for the NetBeans IDE, in oder to convert it to the version for Tomcat, I replaced the file javaeetutorial5\examples\web\hello1\web\WEB-INF\sun-web.xml by a simple web.xml. I will explain the detail of this example in the next tutorial.

Deploy the example in Tomcat

You simply copy the Duke folder into the folder C:\JavaEE\Servers\Tomcat\apache-tomcat-5.5.26\webapps.

Run the example

1. Start Tomcat.
2. Visit the URL http://localhost:8080/Duke in a web browser.
3. In the field, type your name and click the Submit button, you would see the result.

Watch the video clip (play ) for the whole procedure.

V. Running Tomcat on School Machines

Many students use the school machines to work on their Java EE projects, and they do not have the privilege to set the environment variables on the school machines. In this situation, we can use a .bat script to set the environment variables as follows.

1. Create a folder called Tomcat under the C drive.
Here I want to make it simple. Since we install Tomcat on school's machine temporarily, we do not need to use the long path C:\JavaEE\Servers\Tomcat as I recommended before. But if you need to work with other students on the same project, you may need to use the long path as others do.
2. Unzip the file apache-tomcat-5.5.26.zip and extract all the files into the folder C:\Tomcat.
3. (Optional:) Unzip the file apache-tomcat-5.5.26-admin.zip and extract all the files into the folder C:\Tomcat.
When we do not use the administrative tool, we can skip this step.
4. Download the script setenv.bat and put it in the directory C:\Tomcat.
5. Open a command window and cd to the directory C:\Tomcat.
6. At the command line, type the following command,

setenv

You would see all the environment variables needed for Tomcat are set in this window. If you use a new window, all these environment variavles are gone. You need to reset them if you want to use them.
7. In the same command window in which you set the environment variables, cd to the directory C:\Tomcat\apache-tomcat-5.5.26\bin.
8. Type the ollowing command to start Tomcat.

startup

Then you can work on Tomcat as usual.

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