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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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!
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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
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
Related technical and longer articlesLoad Balancing and ClusteringThe proxy jServ, jk, jk2, warp and jk story
|Articles and tips on this subject||updated|
|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 ...
|3680||How 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 ...
|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 ...
|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 ...
|2325||Apache, 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 ...
|2273||Three 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 ...
|1939||mod_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 ...
|2062||Virtual 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 ...
|1006||Apache 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, ...
|1944||Forwarding 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 ...
|1767||mod_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 ...
|1566||Strange 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 192.168.200.162 80
Connected to 192.168.200.162.
|1376||Choosing 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 ...
|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 ...
|631||Apache 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
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.
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