In this whitepaper, we will make a powerful comparison between the two choices that businesses have for building XML-based web services: the Java 2 Platform, Enterprise Edition (J2EE) 1 , built by Sun Microsystems and other industry players, and Microsoft.NET 2 , built by Microsoft Corporation. Some of the statements we make will offend you, and hopefully more of them will agree with you. So as you read this paper, please remember our three promises: 1. We promise to compare these choices at a logical, neutral, and unbiased level. 2. We promise to tell the tale about how we really do feel about these technologies. 3. We promise to dispel the Fear, Uncertainty, and Doubt (FUD) that exists in the marketplace today. Although both J2EE and .NET cover a great deal of technologies and standards, we will focus specifically on building server-side systems as web services using these architectures (for example, we will not be mentioning Jini or Office XP). After reading this white paper, you will have a solid understanding of how these architectures compare, and be empowered to make intelligent decisions in new web services initiatives. The first half of this whitepaper is background information about web services, J2EE, and .NET. If you already understand these technologies, feel free to skip ahead to the 2nd half of the paper, which is the juicy comparison.