Author Alan Johnston has written an erudite yet comprehensible little volume on the eminently sexy network technology known as session initiation protocol (SIP). SIP is basically in its infancy, with a great deal of potency to offer the future of mobile technology. While the first edition of his book saw SIP through its infancy, the second edition brings the young protocol into its adolescence, with all the future promise of adulthood.
The author begins by covering some background for the understanding of the protocol. The example message exchanges will introduce SIP as defined by RFC 3261. Next, the types of clients and servers in a SIP network are introduced and defined. Then Johnston covers the types of SIP requests called methods, followed by the types of SIP response messages and the header fields present in SIP messages. Next, related Internet protocols mentioned or referenced in other sections of the book are introduced, along with details on the use of the protocol with SIP. Then Johnston compares SIP to another IP telephony signaling protocol: the International Telecommunication Union (ITU) recommendation H.323, entitled "Packet-Based Multimedia Communication." Next, the mobility features of SIP are explored further. Finally, the author discusses some future areas of work in SIP-related working groups in the Internet Engineering Task Force (IETF).
This excellent book is written for practitioners, and for those who need to know the intricacies of the protocol. It is an outstanding reference that you will want on your bookshelf if you are involved in the design of networking or new applications. John R. Vacca
John R. Vacca, the former computer security official (CSO) for NASA's space station program (Freedom), has written nearly 40 books about advanced storage, computer security, and aerospace technology.