Continuing with my line of Windows Azure posts of late, I wanted to unearth a feature called Windows Azure Web Sites Always On.
This feature is tucked away in the Configure options for a Windows Azure Web Site. The feature is only available to Standard mode web sites so you will not get this option if you are using the Free or Shared service tiers (sorry). When enabled, Windows Azure will regularly generate a simple HTTP request to the website which means for sites that are based on ASP.NET or other server-side compiling technologies, the website stays warm so that when your first visitor after a period of inactivity hits the site, they aren’t left waiting for it to compile, render and present itself.
Details of the feature are a bit scarce so I haven’t been able to determine yet exactly what the Always On request consists of. The lack of information or configuration options would suggest that it’s as simple as a HTTP GET request to the URL configured in the Site URL field for the web site. There doesn’t either seem to be any indication as to how often this request is issued. If you are already using the Monitoring Endpoints feature or if you are monitoring your web sites with System Center Operations Manager 2012 (SCOM), Global Service Monitor (GSM) for SCOM or another monitoring product then are you are essentially performing this Always On keep-alive activity.