Exercises, examples and other material relating to training module A690. This module is presented on Private Courses
and Specially Run Courses
If you've too much web traffic for a single server,
or you need multiple servers for robustness in the
event of a failure, you'll need a scheme for clustering
or balancing. Specialised hardware solutions are possible,
but you can also use an instance of Apache httpd to front
a number of back room servers (httpd, Tomcat or something
Related technical and longer articlesLoad balancing and robustness - httpd, tomcat, PHP, Servlets, MySQLLoad Balancing and ClusteringThe proxy jServ, jk, jk2, warp and jk story
|Articles and tips on this subject||updated|
|4432||Java web application for teaching - now with sessions and clustering / load balancing demonstrations|
I regret naming "latmjdemo" with that name when I prut together a web application for the Java version of our web deployemnt course. The nameing isn't random:
• L - Linux, the operating system
• A - Apache - the Apache httpd web server that's commonly used to front web sites
• T - Tomcat ...
|1121||Sharing the load with Apache httpd and perhaps Tomcat|
"Can you show us how to share the load of a web site between various servers" is one of the question that comes up quite often on the more advanced web server configuration courses that we run. And, yes, I can, but I'll probably ask you a lot of extra questions about exactly how you want to load balance ...
|3892||Distributed, Balanced and Clustered Load Sharing - the difference|
If one web server isn't enough to handle all your traffic, you can share the load. But you need to be careful that you "maintain state" for your visitors if you're running applications that involve a series of forms / inputs that follow on from each other.
Specialist hardware load sharing devices ...
|3339||Simplest ever proxy configuration?|
Scenario ... Apache Http Server fronting an Apache Tomcat server. Http Server has mod_rewrite and mod_proxy installed.
When we first did httpd and Tomcat courses, getting the two to talk to each other involved builds of extra modules and all sorts of configuration. I did my "simplest ever" this ...
|3293||Distributing the server load - yet ensuring that each user return to the same system (Apache httpd and Tomcat)|
Have you ever tried to sort out a complex situation with a supplier - perhaps something's gone wrong with your electic and gas bills (as happened with us a couple of months ago, when our gas payment got credited to our electic account with the same company). You get on the phone, and the initial person ...
|2483||Clustering on Tomcat|
Subject: Clustering, using Apache http server (version 2.2.14 in my example) with mod_proxy_balancer as the front load splitter and Apache Tomcat 6.0.20 as the replicated application engine. [[Tip should also work for other recent 2.2.x and 6.0.x versions]]
This is a follow on article from ...
|2482||Load balancing with sticky sessions (httpd / Tomcat)|
Subject: Load balancing with sticky sessions, using Apache http server (version 2.2.14 in my example) with mod_proxy_balancer as the front end balancer and Apache Tomcat 6.0.20 as the application engine. [[Tip should also work for other recent 2.2.x and 6.0.x versions]]
When you have too ...
|2059||Sharing the load between servers - httpd and Tomcat|
If you're running a lot of traffic through an application, it's possible that one web server can't cope ... not so much because of the traffic levels, but because oomph the computer. Customer's applications range from financial to transport planning. The amount of compute behind the calculation of ...
|1995||Automated server heartbeat and health check|
Occasionally - very occasionally - we may have a problem on our public facing web server that's hosted in some network operation centre or other. It could be a software glitch, or it could be an internet connectivity issue. And we need to know about it quickly!
The problem is than none of us might ...
|1993||Load Balancing - Hardware or Software?|
If you're fortunate enough to be looking after a web site that's so busy that a single server can't handle all of your traffic, what should you do?
One popular approach is to use a piece of specialised hardware - a load balancer - that sits in front of your network and distributed requests to a series ...
|1771||More HowTo diagrams - MySQL, Tomcat and Java|
Here are some more diagrams "off the wall" from last week - showing "howto" and "whatis" information for Tomcat, Java and MySQL
Some Tomcat and Java Fundamentals
On the right of the board ... the main java programs ...
• the Java compiler is called javac
• the Java Virtual machins is in a ...
|934||Clustering, load balancing, mod_rewrite and mod_proxy|
"It's not friendly - it's like a reference book". Customer comment on yesterday's tailored training day, where we were load balancing a web application between a number of back end servers, using Apache httpd, with mod_proxy and mod_rewrite to do the clever bits.
Our customers are right - it IS tough ...
Examples from our training material
|server.xml|| Tomcat 6.0 server.xml with named jvmroute|
Some modules are available for download
as a sample of our material or under an Open Training Notes License
for free download from [here]
Topics covered in this module
What is clustering?
What is load balancing?
Which should you use?
Keeping the cluster or balance servers in step.
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