Thomas Erl is the world's top-selling SOA author, the Series Editor of the "Prentice Hall Service-Oriented Computing Series from Thomas Erl" (www.soabooks.com), and the Editor of the SOA Magazine (www.soamag.com). With over 90,000 copies in print world-wide, his books have become international bestsellers and have been formally endorsed by senior members of major software organizations, such as IBM, Microsoft, Oracle, BEA, Sun, Cisco, Intel, SAP, and HP. His most recent title ("SOA Principles of Service Design") was released in 2007, and his fourth and fifth titles ("Web Service Contract Design & Versioning for SOA" and "SOA Design Patterns") were jointly authored with industry experts and are scheduled for publication this year.