On the Qandidate.com blog there's a new post looking at fault tolerant programming in PHP, a follow up to their previous post introducing the topic and creating a "circuit breaker" to prevent major issues when a problem pops up.
Now we will show you a running demo of the application where the circuit breaker library Phystrix is combined with asynchronous programming. The advantage of this approach is that it allows the querying of multiple backend services asynchronously. A timeout can be set for each of the calls and the circuit breaker will deal with failing services.
A screencast included in the post shows a script in action and how it reacts when the various services it needs fail. They've posted the code for the demo can be found over on GitHub and full instructions to run it are included in the post. Also included is some of the output from the test and a peek inside the logs showing where things were broken and if they were able to recover.