Google said recently that it will  (Extensible Messaging and Presence Protocol), which is used for instant messaging in Google Talk. A unified Google Hangouts service will extend and replace Google Talk over time, and doesn’t rely on XMPP, a protocol Google helped design and popularize. Immediately after the announcement, Google turned off “federated” access in Google Talk, which previously enabled Google users to communicate with those at non-Google XMPP servers. For Mac OS X users, this change reduces the utility of Messages, which — despite its many flaws — can act as a unified location for all text-based chat and some audio and video sessions.
XMPP had multiple purposes. It was a standalone messaging protocol that could be used for instant messaging as well as other kinds of signaling between individuals, software, and devices. XMPP servers are run by individuals and companies for their own social and business purposes, and by social networks (like Google Talk and Facebook) to provide instant messaging between members. Mac OS X Server includes an XMPP service. XMPP remains active for now in Google Talk, allowing the use of third-party software like Messages, but is not and will not be supported with Google Hangouts.
The protocol was also intended as a universal connector for chat services. Some services that had their own proprietary protocols and client software would allow XMPP connections and discovery. That makes it possible to use an XMPP client to talk with that proprietary service through a gateway to users within its network, as well as also communicate in a single logged-in session with other XMPP accounts on the local server and on other public XMPP servers. “Federation” of this kind between XMPP servers decentralizes authority, and puts more control in the hands of individual users as to how they interact with a network.
Google allowed such federation among other XMPP servers, and Google Talk users could be logged into Google’s Web app, Apple’s Messages, or other XMPP clients and see not only users on the Google Talk network, but also those on other XMPP networks. That feature on 15 May 2013 at the announcement of the transition to Google Hangouts.
Unfortunately, using a partly or fully “walled garden” approach — almost exclusively the case in the past and now coming around again — seems to give a competitive edge to a single company. Google can’t be criticized for moving to its own proprietary standard and locking out other software without also noting that Apple’s iMessage system blocks all third-party access and software, whether in iOS or on a Mac. Microsoft and Yahoo have been much more open about interchange, despite having tens of millions of active users on their networks.
The Electronic Frontier Foundation that goes beyond the technical and competitive one, stating that Google switching from XMPP is bad news for user privacy, because open, competitive systems prevent any one party from making unilateral decisions about how they respect user privacy. And, while Google Talk lets you change one setting for all conversations to be “off the record” (not stored in a transcript on Google’s servers), Google Hangouts  every time you chat, even if it’s with the same person or people. (Google Hangouts also removes “presence,” where you set or allow software to show your current status of available, busy, away, and so forth.)
Apple’s Messages app isn’t limited to just iMessage, and includes prefabricated account styles for adding AIM, Google Talk (XMPP style), and Yahoo accounts, as well as generic XMPP accounts (which Apple still labels Jabber, the original XMPP chat service). The XMPP option lets you plug the values in for your local server or for Facebook and other public servers.
It’s possible to extend Messages on the Mac, too, as Steve Streza did with, which ties App.net private messages directly into Messages as if it were just another chat service. (See “ ,” 9 May 2013, for more on App.net.)
Just like Apple, Google wants control over the chat experience to further bind users to its network and its products (mostly advertising). By controlling the user experience, it can arguably ensure that it’s better, instead of being watered down to the lowest-common denominator required by XMPP. But the Internet abhors walled gardens, and it’s far past time to have a moat and keep the drawbridge up — whether with Google’s new move or Apple’s iMessage siege mentality.