A new book co-written by Ericsson’s Kristoffer Gronowski gives application developers the know-how to know to create SIP-based services for IMS and beyond. 

As the internet and telecommunication worlds continue to merge, IP Multimedia Subsystem (IMS) and its core technology, Session Initiation Protocol (SIP), are playing a critical role.

Kristoffer Gronowski, senior software architect at Ericsson, says that up until now there has not been a thorough, practical guidebook explaining SIP from top to bottom. He says that a lack of knowledge surrounding the implementation of SIP was the main reason he wrote the book titled, Understanding SIP Servlets 1.1.

Gronowski, who has been working with SIP since its early days in 2001, says that even for experts, SIP can feel a bit complicated. “The patterns of session-based communication are much more complicated than the ‘request-and-wait’ behavior that is typical for web surfing. With IMS, it is about building up a service chain.” he says.

Although a basic standard has existed since 2003 a more advanced SIP standard that can be applied in more complicated IMS scenarios has been missing, leaving developers to figure things out for themselves.

Gronowski says that Understanding SIP Servlets 1.1 is intended to be a practical guide providing the ‘know-how’ to developers looking to create new SIP-based applications. And because the primary driver for IMS adoption is the availability of new engaging services, the more developers that can do this, the better it is for the IMS ecosystem.

“It’s hard to say what the next killer app is going to be. There will be those that interest a small number of niche users and others that appeal to a mass market but all of them will need IMS. My philosophy is to get as many services out there and then see which ones become successful,” Gronowski says.

Understanding SIP Servlets 1.1 is intended for developers and system architects of almost all levels with chapters introducing IMS, SIP APIs and web-client interfaces as well as practical chapters that give examples of Ericsson’s own open-source code, SailFin and more advanced development scenarios.

“The goal is to help any developer create a semi-professional service from scratch,” Gronowski says.

Understanding SIP Servlets 1.1 was co-authored by Chris Boulton, chief technology officer at NS-Technologies. He says that SIP servlet technology is rapidly expanding into emerging multimedia communications networks.

“Our hope is that this book will provide a relevant companion to those wanting to learn more,” Boulton says.

In addition to the book, Gronowski also works to support SIP service development. Using the Mobile Java Communication Framework (MJCF), Ericsson offers developers the opportunity to have their applications hosted and gain real experience in a live environment.

Gronowski says that Ericsson is working to bridge the gap for developers between development activities and deployment in live networks.

Ericsson has a vested interest in seeing SIP gain traction in the developer community and has its own portfolio of SIP servlet-based products and services including: Push to Talk, presence and group management, IMS messaging, personal ring-back tones, IPTV and the Ericsson Composition Engine.

“IMS rests entirely on SIP. It is the most important technology,” he says.

SIP Servlets 1.1 is available at Amazon.com or from the publisher, Artech House. Be sure and use the promotional code, EDC09 to receive a 15 percent discount from Artech’s online store.

By David Francisco