What is Tomcat? A Comprehensive Guide to Apache Tomcat Server

Apache Tomcat is a powerful, Java-based web application server that provides support for Java Servlet and JSP technologies. It enables the deployment and execution of WAR (Web Application Archive) files and includes a self-contained HTTP server for seamless web hosting.

Key Tomcat Configuration Paths:

• CATALINA_HOME: /usr/local/jakarta/tomcat
• CATALINA_BASE: /usr/local/jakarta/tomcat
• JAVA_HOME (JDK Path): /usr/local/jdk

Tomcat Log Files:

Monitor logs using the following command:

tail -f /usr/local/jakarta/tomcat/logs/catalina.out | egrep domain.com

• Logs are stored in: /usr/local/jakarta/tomcat/logs/catalina.out

Deploying WAR Files in Tomcat

By default, WAR files are automatically deployed during startup. This behavior can be disabled per host using the deployOnStartup attribute.

• Extract a WAR file using:

unzip example.war

Directory Structure After Extraction:

META-INF/
META-INF/MANIFEST.MF
helloworld.jsp
WEB-INF/
WEB-INF/web.xml
index.html

WAR files are scanned every 10 seconds in the appBase directory.

Deployed applications reside in:
/usr/local/jakarta/tomcat/work/Catalina/example.com/war_file_name/

Tomcat Configuration Files

Tomcat’s configurations are primarily stored in XML format:

• Main Configuration Directory: /usr/local/jakarta/tomcat/conf/
• Apache HTTP Server Configuration: /usr/local/apache/conf/httpd.conf
• mod_jk Configuration: /usr/local/apache/conf/jk.conf

mod_jk Setup for Apache-Tomcat Integration

The mod_jk module enables communication between Apache HTTP Server and Tomcat.

Example Configuration for mod_jk:

LoadModule jk_module modules/mod_jk.so
JkWorkersFile /usr/local/jakarta/tomcat/conf/workers.properties
JkLogFile /usr/local/apache/logs/mod_jk.log
JkLogLevel info
JkLogStampFormat “[%a %b %d %H:%M:%S %Y]”
JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories
JkRequestLogFormat “%w %V %T”

JkMount Configuration (Mapping Requests to Tomcat Workers):

<IfModule mod_jk.c>
    JkMount /*.jsp ajp13
    JkMount /servlet/* ajp13
    JkMount /servlets/* ajp13
    JkMount /*.do ajp13
</IfModule>

Configuration files for individual sites are located in:

/usr/local/apache/conf/userdata/std/1/tom/tomcat.com/cp_jkmount.conf

WAR Deployment in cPanel Using mod_jk

To deploy a WAR file in a cPanel account:

1. Upload the WAR file to the public_html directory of the user’s account.
2. Configure mod_jk to recognize the application.
3. Add a JkMount directive to the site’s include file and restart Apache HTTP Server (httpd).

Example cPanel WAR Deployment Configuration:

<IfModule mod_jk.c>

JkMount /*.jsp ajp13

JkMount /servlet/* ajp13

JkMount /servlets/* ajp13

JkMount /*.do ajp13

JkMount /appname/* ajp13

</IfModule>

Useful Tomcat Resources:

• Apache Tomcat Project Page: http://tomcat.apache.org/
• JDK Download: http://www.oracle.com/technetwork/java/javase/downloads/index.html
• Tomcat Configuration Tips: http://oreilly.com/java/archive/tomcat-tips.html