XMPP rises to face SIMPLE standard

Vendor coalition challenges standard used by Microsoft and IBM

With the lure of presence-aware applications and systems dangling before them, competitors are warming up for a heated race to establish an industry standard protocol for presence awareness and instant messaging interoperability.

Lines are drawn between two protocols currently working their way through the Internet Engineering Task Force (IETF) standards body: the SIP (Session Initiation Protocol)-based SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) and the open-source, XML-based protocol XMPP (eXtensible Messaging and Presence Protocol). Vendors are placing bets, hoping to choose the correct side of the market's eventual shakeout.

Whereas Microsoft and IBM have thrown their weight behind SIMPLE, a groundswell of support is rising behind XMPP, as Hewlett-Packard, Intel, Hitachi, Sony, and others invest in the technology.

Intel's Wireless Communications and Computing Group chose XMPP-based IM vendor Jabber last month. HP plans to deepen its XMPP support with a forthcoming distribution and systems integration deal with Denver-based Jabber.

Often referred to as the Linux of IM, XMPP was developed in the open-source community during the late 1990s and then submitted to the IETF for standards consideration. This month XMPP reached working group final-call status within the IETF. The protocol is within months of reaching final ratification as an IM and presence awareness standard, according to PeterSaint-Andre, executive director of the Jabber Software Foundation, the Jabber-sponsored, open-source organization fostering XMPP's development.

For its part, SIMPLE is also progressing through the IETF but is expected to be completed after XMPP. With weighty stamps of approval from both Microsoft and IBM, SIMPLE is perceived by many to be the clear winner in the IM and presence standards race.

But some observers have noted technical issues with the protocol that have caused some early users to seek alternatives. SIMPLE is a set of IM-related extensions for the IP-based signaling protocol SIP, originally designed to enable IP telephony and other direct Internet connections. Critics charge that because it uses a signaling protocol for data exchange, SIP is ill-suited for IM and presence functionality.

"I put no faith in SIP and SIMPLE as the basis for IM interoperability standards," said analyst Rob Batchelder, president of Relevance, a strategy consulting group in Trumbull, Conn. SIP was intended for applications such as VoIP, but there is "now an effort to take SIP and use it to provide basic enabling capabilities for global IM interoperability. The problem is that SIP was not intended to be that."

The SIMPLE extensions that address IM have not been clearly thought out, Batchelder added. The problem with SIMPLE, he said, is that the approach of using standards-based gateways between IM systems is architecturally unsound, because they add delays and introduce messaging transmission problems.

"The work of SIMPLE to provide IM-based gateways that use SIP is a technology that is as full of holes as Swiss cheese," Batchelder said. SIMPLE also has trouble with scalability and lacks basic capabilities such as buddy list management and presence description, publication, and subscription, he added.

Moreover, because the SIMPLE protocol is still incomplete, IBM's and Microsoft's implementations have required the addition of proprietary extensions to make their offerings work. Admitting that its forthcoming Microsoft Real-Time Communications Server 2003 contains propriety extensions to fill out the SIMPLE protocol, Microsoft steadfastly maintains its commitment to the SIMPLE standard as it matures. "We are absolutely committed to being SIMPLE compliant," said Ed Simnett, lead product manager of RTC Server at Redmond, Wash.-based Microsoft.

"SIMPLE is not a mature protocol at this point, so we've taken a snapshot and implemented against that," Simnett said. "As we make subsequent releases, we will be looking to make sure we are absolutely compliant to the standard." In fact, Microsoft views SIMPLE as a superior technology choice because of its extensibility into other media types such as audio, video, file transfer, and whiteboarding, according to Simnett.

"One of the reasons we picked SIP and SIMPLE is because it allows more than presence and IM. We think that one of the most exciting long-term vision areas here is making sure IM and presence become base building blocks in the broader real-time communications arena," Simnett said. "Other protocols focused too much just on instant messaging and not enough on the other media types we think will be important."

Having just shipped a SIP gateway for its Sametime IM platform in November, IBM Lotus also maintains its commitment to SIMPLE. The standard is young and vendors are implementing it differently, but interoperability is the goal, according to Kevin McLellan, marketing manager of workplace collaboration products at IBM Lotus in Cambridge, Mass. "The fact that the largest industry players, [IBM] and Microsoft, are supporting SIP and SIMPLE suggests we will work to make sure that the standard evolves to achieve interoperability. That is the goal. We are also working hard to make sure it evolves in the right way." IBM intends to add native SIMPLE support to Sametime in a subsequent release, McLellan added.

Also adding to SIMPLE's momentum, Sun Microsystems, another big-name infrastructure player, plans this month to deliver SIMPLE support in its newly released Sun ONE (Open Net Environment) Instant Messaging Server 6.0.

Meanwhile, XMPP's proponents contend it is more mature than SIMPLE and better suited to handle IM and presence awareness. XMPP was built from the ground up as a data transport for messaging, tapping an XML streaming technology that is optimized for real-time data exchange, according to Jabber Software Foundation officials. Because it is based on XML, XMPP is extremely flexible and extensible, said Rob Balgley, CEO of Jabber. "[XMPP] is much more easily integrated in applications beyond instant messaging, allowing other systems to be presence enabled."

But companies eyeing a piece of the presence-awareness-infrastructure pie are wary of falling into a single vendor's proprietary lock-in, said Balgley. "You can't argue with Microsoft, and they will be formidable," he said. "But right now presence-enabled messaging represents an enormous growth opportunity. Companies are not going to leave that decision to Microsoft. They will go and find an alternative technology they can control."

According to Batchelder, although XMPP is a useful protocol that provides a basis for IM system interoperability and is gaining traction in the marketplace, it is not necessarily the magic bullet for interoperable presence architectures.

"The presence model inside XMPP is fairly simplistic and does not adequately address the issues of building a global presence architecture that is scalable and highly distributed on a global basis, said Batchelder.

Whereas enterprise-focused vendors are at least attempting to build toward standards, the consumer networks such as AOL and Yahoo have made no strides toward SIMPLE or XMPP. Those companies have millions of dollars invested in their own protocols and networks and do not have much economic motivation to interoperate at this time.

The need for IM and presence-awareness interoperability will eventually reach a critical juncture as enterprises seek to selectively expose elements of a private presence infrastructure to outside parties such as business partners and suppliers, according to Batchelder. "Companies will build private presence infrastructures and they will want to tie them to the public IM network and clouds," he said.

SIMPLE may eventually glue IBM and Microsoft together, but it won't work industrywide and will be of limited value.

In the end, the industry will most likely rally behind a standard that blends both protocols, Batchelder said. "What the industry ultimately converges around will likely be a hybrid of XMPP, propriety ideas, and some generic work in IETF around SIP and SIMPLE," he said.

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