This article walks you through getting started with load balancing and clustering Apache Tomcat using Apache HTTP server. Following the simple steps, you will learn and experience how clustered Tomcat instances work with a common front-end load balancer.

Enterprise web applications are expected to be scalable, fast and reliable and able to handle fail-over behavior. With increasing traffic on websites, the performance of applications degrades and it is necessary to distribute client requests to different machines in order to perform parallel processing. Besides distributing the requests, it is also important to increase the availability of systems so that if one web server goes down, another web server transparently processes the client request on behalf of the client. Client requests towards web containers are distributed using a common front-end load balancer and high availability is achieved using a set of clustered machines with the same set of files and similar configuration. There are various solutions for load balancing and clustering. 

This article walks you through getting started with load balancing and clustering Java 2 Enterprise Edition (J2EE) web containers using a sample configuration. We will use the following open source tools on Windows 2000:

1.      Apache Tomcat-5.0.30 as a web container.
2.      Apache HTTP Server 2.0.59 to front the clustered Tomcat servers
3.      mod_jk 1.2.6_2.0.50 connector to integrate Apache with the clustered Tomcat servers.

The system architecture we will demonstrate looks like this:

By Rehman Adil