XMPP vs SIMPLE: The race for messaging standards

There’s a race on for the future of the enterprise messaging system. The contestants are backing competing protocols for IM and presence awareness. Which standard takes home the prize may depend less on technical merits than on brute force. At the head of the competition are SIMPLE (Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions) and the open-source, XML-based XMPP (eXtensible Messaging and Presence Protocol). Both are currently being developed by the Internet Engineering Task Force (IETF).

SIMPLE backers extol the broad media possibilities of a SIP-based signaling protocol with natural affinities for voice, video, and conferencing. XMPP proponents, on the other hand, tout an XML-based data transport technology that is built to manage IM and presence.

As it now stands, real-time communications in the enterprise is in its infancy. The long-term goal is to develop a single protocol that not only unifies real-time messaging with the tracking and notification of worker presence and availability but also allows for those functions to be performed across corporate boundaries and on a vast range of devices.

Beyond basic IM system interoperability, a common protocol for IM and presence holds the key for unlocking valuable state awareness from the tethers of a stand-alone system. The challenge of stitching availability awareness into a variety of systems — both within and between enterprises — is piquing the interest of heavy hitters. IBM and Microsoft have stepped up to the plate to declare standards compliance, regardless of whether the market or the protocols themselves are ready.

“It is very important here at this [early] stage of enterprise IM [for vendors] to say, ‘We are compliant with these standards.’ It is more important to say it than to do it,” says Robert Mahowald, research manager at IDC in Framingham, Mass.

The favored SIMPLE

SIMPLE is a set of extensions to the established SIP protocol that initiate, set up, and manage a range of media sessions, including voice and video. SIMPLE extensions define SIP signaling methods to handle the transport of data and presence.

SIMPLE’s designers set out to develop a system that represented the communications state as broadly as possible, supporting presence not just for PC messaging applications but also for devices such as phones and PDAs, says Jonathan Rosenberg, chief scientist at Parsippany, N.J.-based dynamicsoft and co-author of SIP and SIMPLE.

“We realized a long time ago that presence and IM [are] just another facet of communications, and that is what SIP is all about. IM is just like voice and video; it is another aspect of real-time, person-to-person communications,” Rosenberg says.

SIMPLE’s capability of unifying voice, video, and data messaging appealed greatly to Microsoft, according to Ed Simnett, lead product manager of RTC (Real Time Communications) Server at the Redmond, Wash.-based software giant.

According to observers, one potential problem with SIMPLE is that it is a paging protocol meant to perform signaling but not to carry anything else. “[SIMPLE] can carry a brief conversation, which is great for single-session IM traffic and SMS traffic, but it is not very good for doing the heavy load to carry things like data signals or video signals on top,” IDC’s Mahowald says. “There is where you have to deviate from the standard to create your own extensions.”