It comes with a pre-set library and customized configuration which are implemented and tested as per industry standards. A few advantages of using the binary package are:

RPM is defined as a system installer, which is developed and compiled on each OS independently. It has a pre-defined library, which will work only on the respective OS. A few advantages of using RPM are:

The only disadvantage is, we cannot configure multiple instances in a single operating system and it has predefined paths.

You can customize the installation based on your requirements using the source package. Suppose you want to customize during installation of the software, it can be done in this package.

Java has been developed by many vendors. Based on the application requirement and type of architecture, different JVMs are used by various applications. Common JDK vendors are IBM, HP, Sun, OpenJDK, and so on. Sun holds a major stake in IT industries. JDK is widely used and accepted across various IT industries.

JDK packages are available for each OS and can be compiled on any system using a common set of libraries. These packages are easily available on the Internet or already integrated with different OS vendors.

JDK/JRE comes in 32 bit and 64 bit editions, so we can use it based on the application requirement. Some of the performance characteristics of the 64 bit versus 32 bit Virtual Machine (VM) are:

After the installation of Java on a different OS, it's now time to set the environment variables for Tomcat at the OS level. In order to run Tomcat, we have to define the JAVA_HOME as an environment variable and set the path for Java so that it can be accessed from any partition of OS.

What is JAVA_HOME?

JAVA_HOME is the JDK install directory, for example, C:\jdk6. It is meant to be set as an environment variable and referenced in Windows batch files or Unix scripts. In Tomcat, JAVA_HOME is defined in catalina.sh under TOMCAT_HOME/bin. The following screenshot shows the definition of JAVA_HOME in Tomcat 7. Once you execute startup.sh, it internally calls catalina.sh and invokes JAVA_HOME. In a production environment, it is always recommended to use the permanent environment variable.

Setting the JAVA_HOME and the PATH environment variable in Linux

The environment variable and path are set differently in Linux as compared to Windows. Perform the following steps to set the environment variable in Linux:

1. Open the .bash_profile using the vi editor for the root user.

   Note

   You can put the environment variable in bashrc also. It will also execute at the time of the user login.

2. Add the following environment variable in the file. The following is the code snippet of .bash_profile. The highlighted code shows the declaration of JAVA_HOME and PATH. export will add the JAVA_HOME and PATH to the system parameter for every user login.

   # .bash_profile
   # Get the aliases and functions
   if [ -f ~/.bashrc ];then . ~/.bashrc
   fi
   # User specific environment and start-up programs
   JAVA_HOME=/opt/jdk1.6.0_24 PATH=$JAVA_HOME/bin:$PATH:$HOME/bin export PATH JAVA_HOME
   unset USERNAME
   

3. Save the .bash_profile using the :wq command.
4. Once you have saved the .bash_profile, then you have to logout and re-log in to the environment to activate the changes using the following command:

   su - username su - root (as our user is root)
   

   Note

   If we run the previous command for any user, then the profile of that user will be reloaded.

Also, you can run the env command to verify the environment variables are configured properly, as shown in the following screenshot:

Tip

It is always best practice to first take the backup of the existing profile. In case there are issues while doing the changes, then we can revert back the changes using the command cp

[root@localhost ~]# cp .bash_profile .bash_profile_backup.

Now we have set the environment variable for Windows and Linux environments, but how can we verify whether the environment is set properly or not?

Before we start installation of Apache Tomcat 7, let's quickly verify the environment variable on both the OSes.

In the Windows environment, variables can be verified using the following command:

echo %VARIABLE_NAME%

For JAVA_HOME:

C:\Users\user>echo %JAVA_HOME% C:\Program Files\Java\jdk1.6.0_24

For PATH:

C:\Users\user>echo %PATH% C:\Program Files\PC Connectivity Solution\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\ Program Files\Broadcom\Broadcom 802.11\Driver; C:\Program Files\Java\jdk1.6.0_24\bin

In Linux, we can use the following command to verify the environment variables:

echo $VARIABLE_NAME

For JAVA_HOME:

[root@localhost ~]# echo $JAVA_HOME /opt/jdk1.6.0_24

For PATH:

[root@localhost ~]# echo $PATH /opt/jdk1.6.0_24/bin:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/ sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

After verifying the environment variable on both the OSes, we are sure that JAVA_HOME and PATH are properly set in the environment. We have completed the prerequisites of installation of Apache Tomcat 7. Now, we can proceed with the installation of Apache Tomcat 7.

In this topic, we will discuss the steps involved during the software installation of Tomcat 7. Following are the steps:

Installation of Tomcat 7 is quite simple in a Linux environment as compared to Windows. It can be done in just three steps:

After this step, the installation of Tomcat is complete in Linux.

In Windows, we can start/stop the services using two methods:

The Linux startup process is completely different. Here, we have to run the startup/shutdown scripts manually to bring the services online. Let us start the services on Linux to verify the installation.

Before that, let's quickly verify the configuration. Tomcat 7 comes with different scripts, through which we will verify the complete installation. There is a very good script placed in the Tomcat bin directory named as version.sh, through which we can verify the complete Tomcat version and system information. Let's run the script using the following command:

[root@localhost bin]# ./version.sh Using CATALINA_BASE: /opt/apache-tomcat-7.0.12 Using CATALINA_HOME: /opt/apache-tomcat-7.0.12 Using CATALINA_TMPDIR: /opt/apache-tomcat-7.0.12/temp Using JRE_HOME: /opt/jdk1.6.0_24 Using CLASSPATH: /opt/apache-tomcat-7.0.12/bin/bootstrap.jar:/opt/apache-tomcat-7.0.12/bin/tomcat-juli.jar Server version: Apache Tomcat/7.0.12 Server built: Apr 1 2011 06:13:02 Server number: 7.0.12.0 OS Name: Linux OS Version: 2.6.18-8.el5 Architecture: i386 JVM Version: 1.6.0_24-b07 JVM Vendor: Sun Microsystems Inc.

There is one more script in the Tomcat bin directory that is very useful. configtest.sh is used to check any configuration changes in scripts. This script performs a quick configuration check on the system and finds the errors. Let's run the script using the following command:

[root@localhost bin]# ./configtest.sh Using CATALINA_BASE: /opt/apache-tomcat-7.0.12 Using CATALINA_HOME: /opt/apache-tomcat-7.0.12 Using CATALINA_TMPDIR: /opt/apache-tomcat-7.0.12/temp Using JRE_HOME: /opt/jdk1.6.0_24 Using CLASSPATH: /opt/apache-tomcat-7.0.12/bin/bootstrap.jar:/opt/apache-tomcat-7.0.12/bin/tomcat-juli.jar May 22, 2011 4:06:16 PM org.apache.coyote.AbstractProtocolHandler init INFO: Initializing ProtocolHandler ["http-bio-8080"] May 22, 2011 4:06:16 PM org.apache.coyote.AbstractProtocolHandler init INFO: Initializing ProtocolHandler ["ajp-bio-8009"] May 22, 2011 4:06:16 PM org.apache.catalina.startup.Catalina load INFO: Initialization processed in 1401 ms

After doing the configuration check, start the Tomcat services. The Tomcat services can be started using the startup.sh in the bin directory.

To start the Tomcat services, you have to perform the following mentioned steps:

A Tomcat shutdown script is also available in the bin directory named as ./shutdown.sh. Let's execute the script to know the output. The details are as follows:

[root@localhost bin]# cd /opt/apache-tomcat-7.0.12/bin/ [root@localhost bin]# ./shutdown.sh Using CATALINA_BASE: /opt/apache-tomcat-7.0.12 Using CATALINA_HOME: /opt/apache-tomcat-7.0.12 Using CATALINA_TMPDIR: /opt/apache-tomcat-7.0.12/temp Using JRE_HOME: /opt/jdk1.6.0_24 Using CLASSPATH: /opt/apache-tomcat- 7.0.12/bin/bootstrap.jar:/opt/apache-tomcat-7.0.12/bin/tomcat-juli.jar