The book is a collection of source material for use by enterprise architects working with Service-Oriented Architecture (SOA). It consists of material that has been considered and in part developed by The Open Group SOA Working Group1. The SOA Working Group is engaged in a work program to produce definitions, analyses, recommendations, reference models, and standards to assist business and information technology professionals within and outside of The Open Group to understand and adopt SOA. This Source Book does not represent the final output of that work program, which will be published as a collection of Open Group Standards and Guides. It is an interim publication, and its content will not necessarily be reflected in the final output.