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For 2023 - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Web Application Deployment module A608
Apache httpd mod_proxy
Exercises, examples and other material relating to training module A608. This module is presented on Private Courses and Specially Run Courses only

mod_proxy provides the mechanism through which you can forward certain requests to a web site which enter through a single portal to other servers - it allows you, for example, to pass on requests for pages that are to be generated by a Java application to an Apache Tomcat server, and to pass on requests that will be heavy on resources to other servers to leave your main portal server clear for traffic regulation and lighter requests.
Related technical and longer articles
Load Balancing and Clustering
The proxy jServ, jk, jk2, warp and jk story

Articles and tips on this subjectupdated
1121Sharing 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 ...
3892Distributed, 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 ...
3680How can I run multiple web servers behind a single IP address?
Scenario ... from last week's Linux course. I have several web servers on my network which I want to make publicly available. However, I only have a single incoming IP address, so all incoming web requests go to a single computer in my network. What can I do about this? Option 1 - keep all the web ...
3339Simplest 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 ...
3293Distributing 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 ...
2482Load 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]] Background When you have too ...
2325Apache, Tomcat, mod_proxy
The Apache httpd web server (a.k.a. "The Apache Server") is essentially a file (web page) server, written for fast performance in C, very reliable, and VERY widely used. The Apache Tomcat web server (a.k.a. "Tomcat") is essentially a web application container that runs using web protocols. It's written ...
2273Three recent questions on Tomcat Convertors
Can mod_proxy receive a request in one protocol and forward it in another? mod_proxy (in httpd 2.2.x at least) is capable of protocol conversion - at least from http to ajp. https to http, and https to ajp should also work. mod_proxy_connect provides the capability of onward connection via https ...
1939mod_proxy_ajp and mod_proxy_balancer examples
One of the major enhancements in release 2.2 of Apache httpd is the addition of the mod_proxy_ajp and mod_proxy_balancer modules to the standard distribution. Gone are the days of needing to build special modules such as Jserv, jk, jk2 and warp to have httpd act as a "front" to a Java (Tomcat) server ...
2062Virtual hosting and mod_proxy forwarding of different domains (httpd)
Let's say that you want to set up a single web server to look after several domains, but then have parts of those domains served by other 'back room' servers. This diagram give you the picture - a single incoming IP address / server with all the security and logging stuff on it (and probably handing ...
1006Apache httpd and Apache Tomcat together tips
Many sites run two web servers - Apache httpd is ideal for plain HTML documents and scripts / programs that are single pages, run rarely, not all linked in together. Whereas Tomcat is an application container that suits applications that are run by tens of people all at the same time - great for banking, ...
1944Forwarding session and cookie requests from httpd to Tomcat
If you're using mod_proxy to forward requests that use sessions to other servers, you need to ensure that the cookies get correctly rewritten as they're sent to the browser for setting, in order to reflect the URL of the customer facing server rather than the back end server. Here's an example where ...
1767mod_proxy and mod_proxy_ajp - httpd
Under Apache httpd version 2.2, mod_proxy_ajp provides a neat way for you to forward requests to an appropriately configured Apache Tomcat server using the more terse ajp protocol rather than the verbose http. Here are some sample configuration lines from httpd.conf, forwarding requests under the ...
1566Strange behaviour of web directory requests without a trailing slash
When you call up a web page and you give a directory name WITHOUT a training slash, the web server return a "moved temporarily" page - code 302 - giving you the same name WITH a trailing slash as your new page: Dorothy:~ grahamellis$ telnet 80 Trying Connected to Escape ...
1376Choosing between mod_proxy and mod_rewrite
If you're connecting an Apache httpd server to an Apache Tomcat server, you can do so via proxied http requests - i.e. have your customer facing http server relay the request on, perhaps having modified it, to Tomcat and then passing the response back. Two different Apache modules give you the facility ...
934Clustering, 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 ...
631Apache httpd to Tomcat - jk v proxy
Many of our customers run both the Apache httpd and Apache Tomcat web servers - with good cause, since Tomcat is biased towards web applications where the same code is run many, many times over and httpd is biased towards serving pages and is better tuned for a much larger number of different pages but ...
Examples from our training material
httpd-forwarder.conf   Proxy Forwarder include file for Apache httpd 2.2
httpd.conf   httpd.conf which includes extra proxy forwarder file
proxy.conf   Sample mod_proxy configurations
Background information
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
mod_proxy and mod_proxy_balancer.
mod_proxy_http, mod_proxy_ajp and mod_proxy_ftp.
Double rewrite issues.
Balancing maps.
Complete learning
If you are looking for a complete course and not just a information on a single subject, visit our Listing and schedule page.

Well House Consultants specialise in training courses in Linux and LAMP,Ruby, Lua, Python, Perl, PHP, and MySQL. We run Private Courses throughout the UK (and beyond for longer courses), and Public Courses at our training centre in Melksham, Wiltshire, England. It's surprisingly cost effective to come on our public courses - even if you live in a different country or continent to us.

We have a technical library of over 700 books on the subjects on which we teach. These books are available for reference at our training centre.

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