Morgan Cheng's questions

I have little experience in web site infrastructural architecture design. I know it might be situation specific. The web site is supposed to:

1) Need HTTPS support for some page (e.g. login page) while others are just HTTP page.

2) Need multiple web servers so that some load balancing is required.

3) Need HTTP caching and compression to boost performance.

4) Some requests (e.g. image uploading) should be routed to dedicated backend servers. So, URL-based balancing is required.

I know that NginX and HAProxy are both nice open-sourced Reverse Proxy and/or Load Balancer. Since HAProxy doesn't support SSL, while Nginx load balancing is not as good as HAProxy. I'll take both.

So, should I put Nginx (as reverse proxy) in the front of HAProxy (as load balancer), or opposite?

Thanks

I'm setting up development environment of Apache. I prefer to set a environment variable to be local checked out SVN revision number. The environment variable value is then read in PHP code and put in external JavaScript and CSS URL (as cache bustor). As a result, every time I "svn up" my local code, I got updated JavaScript and CSS URL related to the revision number.

For example, current revision number is 2314 and set to $_SERVER['REVISION']. The PHP page will read this $_SERVER['REVISION'] and render external JS link like this http://www.example.com/2314/home.js. Since there is a revision number in the URL, if local revision is updated, browser cache will be busted for easy development.

Is it possible to achieve this in Apache?

Thanks,

-Morgan

Keep-Alive connection feature in HTTP protocol is meant to reduce TCP connection hits to web server. It should be able to improve web server performance. However, I found that some web servers deliberately disable KeepAlive feature from server side.

In my understanding, some reverse proxy, i.e. HAProxy, disables HTTP keep-alive in order to reduce memory usage which is more critical than CPU usage in some situation.

Is there any other reason why Web server disables Keep-Alive?

Currently, my work environment has only RHEL 5.4. I'd like to try some other Linux distributions, such as Ubuntu, with virtual machines.

Is there any free virtual machine software applicable to linux?

I'm not clear about the difference between Load Balancer and Reverse Proxy. They both seems having same behavior: distributing incoming requests to backend servers.