Facebook Chat in Mac OS X Messages.app

As of 16 Dec, 2015, I noticed that I could no longer log into the Facebook chat service via the Messages.app on my Mac. I'm running/was running Messages.app (Version 9.1 5085) under Mac OS X 10.11.2 (El Capitan) on my 27" iMac and the Messages application for mobile on my iPad Air 2 and an iPhone 6s+ (both running iOS 9.2). After approximately 6 hours of troubleshooting and research I discovered a note for developers on a Facebook page. The Chat API has been deprecated. After April 30th, apps will no longer be able to access the chat service. If your Messages app is no longer able to handle/exchange Facebook chat, this may very well be the reason why. - Robert Vaessen

Copyright note: Screen shot/image below taken from Facebook developers webpage: <https://developers.facebook.com/docs/chat> Just in case that page goes away (and it has).

FYI: The 'recommendation' that people access Facebook messages using Facebook is a bit of a bummer. The whole point of using Messages and the XMPP/Jabber protocol is interoperability with other applications and the ability to create/manage a 'Universal' messaging Application. Apparently (no surprise here) Facebook isn't interested in sharing or allowing users to live outside their ecosystem. This move (deprecating) the Chat API was easily predictable - After all, you can't see Facebook advertisements if your using some other chat client to exchange messages with Facebook members. This is simply a clear case of Facebook doing whatever they can to force members to stay inside their ecosystem and increase revenue by doing so - Screw you Facebook member - We're here to serve the shareholders, not You! (Facebook sees 'you' as the 'product' that they have sold to their 'customers' the 'Advertisers' - If you leave their website, you won't be able to view the advertisements, and they won't be able to gather information about you, which they can then turn around and sell to other 'customers' - So, shut up and watch those ads!