Developing Real-time Apps

Selling a voice-over-IP system is often just the beginning of a long-lasting and profitable solution for many VARs and systems integrators. One of the next steps in that process entails understanding how to develop real-time applications that can take advantage of voice and data convergence.

These often go by the term "presence-aware," meaning that the application understands what users are actually doing, including when they are busy on a phone call or away from their desks.

Here is the deal: When you have a VOIP telephone on your desk, it can be associated with your computer as well, so that if you are on the phone, your incoming callers can be identified in caller ID messages on your PC screen. Or if you want to schedule an audio conference, you can make use of a Web site to quickly set it up. Even better, there are some instant messaging applications that also integrate with the telephone so that people can see your status automatically over their IM software.

"The idea is to create a combination of applications that can be used by call centers and take business processes and alleviate a lot of human latency and error," said Mark Damphousse, chief technology officer of Trinet Systems, of Westwood, Mass. These applications can often bridge the transition from an older telephony PBX to a newer model that supports VOIP, too.

Of course, there are two separate protocol paths that application developers have taken to make this magic possible. One is called SIP (Session Initiation Protocol), and its extension for IM is called SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions). The other protocol is called XMPP (Extensible Messaging and Presence Protocol). Microsoft uses SIP and SIMPLE—although, of course, using its proprietary changes that are yet to be standardized. XMPP has been adopted by Google Talk and Jabber, among many others. Both are used for call control and are supported by numerous vendors for basic presence awareness and convergence communications tasks.

Jabber is "working on aggregating SIP and XMPP and providing a presence service for any application that would need it," said Dave Uhler, marketing vice president for the Denver-based company. "It doesn't really matter which presence protocol you use—the bigger challenge is being able to aggregate the presence information and integrate it into your application," he said.

VARs and systems integrators looking to work in this area need to have solid Java programming skills, said Carl Tyler, founder and CEO of Epilio, in Boston.

"You want to have some knowledge about security and know how to use SSL [Secure Sockets Layer] and TLS [Transport Layer Security] and how to manage certificates properly," Tyler said. "The tool kits are still less than a year old, and there aren't many people that have done this type of programming before. It isn't just writing a simple 'Hello, world' application. You have to understand how to manage queues and be able to scale your application under load, too."

This was actually one of the problems that Microsoft had with its own SIP implementation. "They found that SIP didn't scale very well and needed to rewrite that to add compression to improve performance," said Tyler.

"Organizations need to use a common presence model," said Uhler. "And the VOIP integrator needs to understand how to tie in presence with existing corporate applications such as directory services and e-mail."

David Strom is a technology freelance writer, consultant, blogger and podcaster and can be reached at david@strom.com.