To continue from where I’ve left off on my previous post, this time we’ll setup heartbeat to monitor both of our load balancers, thus allowing us to have what one may call high availability/ failover, between both our load balancers. This method can be used on any server you wish, you can for example have Heartbeat monitor mysql, apache or any other server. In this example, we’ll set up Heartbeat to monitor our crossroads load balancer.
I recently came across the need to have a countdown displayed in one of our applications. I was going to be releasing a new version of our app and wanted the users to have an idea of how long it was going to take until the application was up and running. After a few searches I found a plugin that does just what I needed, it is a jquery plugin, very simple to use and to add to any php application in just a matter of minutes.
(This tutorial assumes you own a legal copy of the OS you’ll be using to install as the “guest” OS, be it Unix, Winblows or any other Operating System not mentioned here)
In this tutorial I’ll walk you through setting up a virtual machine in Linux using QEMU. According to QEMU site, QEMU is a generic and open source machine emulator and virtualizer. When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performance.
This tutorial was written after one of my readers requested help with creating a dependent dropdown menu for continents, countries and states. I hope this helps everyone out there, who like myself, have struggled with this in the past.
First you’ll need to create the connect.php file, explained here.
Next create the 3 mysql/php/json files used for:
1. gathering data from mysql,
2. storing the data into a json array for each of the combo boxes you’ll be using (Continent, Country and State).
(Please adjust the paths to connect.php (mentioned above) and all other files used in this example
accordingly and create the required tables in mysql as needed)
Start by creating the continentQ.php file, to gather the continent data: