A Better HAProxy Health Check For Dynamic Websites
Nobody wants their website to go down, or worse, for users to notice the site is down. Because of this most larger websites will run on multiple servers to provide some level of high availability. In a multi-server architecture there is typically a load balancer (or cluster of load balancers) to distribute the load among a pool of web servers. When a server goes down it’s taken out of the pool until it is once again ready to handle requests. HAProxy (a software load balancer) has the ability to perform this task by doing periodic health checks on all the servers in a cluster. The default settings, though, could give false positives in some cases, and thus create a bad user experience by allowing ill application servers to continue receiving requests.
High Performance Comet on a Shoestring
I’ve had my eye on the advances that are being made in the Comet arena for a while now, but it was only this past weekend that I finally sat down and used it for a project. In doing so, there was a particular configuration problem I needed to address, and that was…uh, addressing.
Introducing Comet to an existing architecture assumes there is already a web server in the neighborhood, and that it is, in one way or another, receiving traffic from port 80. Due to the fact that many site visitors will likely be positioned behind a firewall unwilling to accept connections on ports other than 80 or 443, we also need to get our Comet server running on port 80 as well. This normally wouldn’t be much of a problem at all, unless you don’t want to fork over the money for an extra IP address. I don’t & I didn’t. So let me show you how I did so.
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About
Sean Murphy is a freelance web application developer currently living near Orlando, FL. Aside from building his own applications and contributing to open source projects, he works with clients to provide top-notch consulting & development expertise.
