Thursday, October 29th, 2009

Since the Apache load balancer seems to be my topic of the week, let's focus on another related question: What happens if a worker (backend server) doesn't show up for work? Let's say server B needed to go down for maintenance and is no longer available for the cluster: For this example I simply shut […]

Wednesday, October 28th, 2009

HTTP load balancers have one natural enemy: redirections. For example, a "trailing slash" redirect is issued when the server receives a request for a URL http://servername/dir where dir is a directory. In such a case the server redirects the browser to http://servername/dirname/ (including the trailing slash): # lynx -mime_header http://loadbalancer/dir | egrep Location: Location: http://serverA/dir/ […]

Tuesday, October 27th, 2009

Usually a single AMP system is enough to serve - let's say - around 500 concurrent users. Sometimes more, sometimes less, strongly depending on the particular web application, the overall architecture of your system, of course the hardware itself, and how you define "concurrent users". Nevertheless, if your server gets too slow, you'll need to […]

Thursday, October 8th, 2009

In my last week's blog entry Urban legends: Apache reload(ed) I tried to prove that an Apache reload is quite exactly the same as the restart of an Apache web server. One of my dear readers - yes, at least someone seems to read this blog - pointed out that this is not always true, […]

Monday, September 28th, 2009

What's the difference between reloading and restarting an Apache web server? If you google for this you'll find a lot of (wrong) information which may sum up like this: A reload just let Apache re-read it's configuration file, without restarting the Apache. But if you need to do bigger changes to the config, like adding […]

Friday, September 18th, 2009

The day CGI was invented was a great day for the Internet, but a dark day for the history of how-to-do-thinks-right. CGI was great, because it gave us (standard computer nerds) the ability to easily implement dynamically generated HTML pages - the predecessor of todays web applications. The interface was so ingeniously simple and powerful […]

Wednesday, September 16th, 2009

About two weeks ago I showed a simple way to beautify your URLs and hide the use of PHP as the backend of your web site. Since I got a lot of emails from people indirectly asking me how to also hide the X-Powered-By: PHP header which is still showing up in ones web server's […]

Wednesday, September 2nd, 2009

The Scenario Imagine: You run a popular website using AMP technologies, but your hardware is awfully old and over the years, as your website became more and more popular, it's got slower and slower and slower. Today it runs with a load of 42 and smoke pours out of the TCP ports. And because you're […]

Thursday, August 27th, 2009

One of the advantages of maintaing a popular project like XAMPP is the immense amount of community feedback you get. In other words: your inbox is a daily challenge. PHP 5.3 incompatibilities are hot topics these days. Here's an Apache related one which hits my inbox on a very regular basis. Variant 1 Apache complains […]

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