A friend-of-a-friend of mine built the Red Alert [0] app that sends a push notifications when a rocket is fired from Gaza. Alerts can be as short as 15 seconds, so if you want your Alert to be effective, you have to figure out how to send out several thousand notifications in seconds.<p>[0] <a href="https:&#x2F;&#x2F;redalert.me&#x2F;index_en.html" rel="nofollow">https:&#x2F;&#x2F;redalert.me&#x2F;index_en.html</a>