Through the years, Microsoft has released various middle-tier technologies to help architects and developers design and implement n-tier solutions. And through the years, we have utilized these technologies to build our applications. Some of the technologies, such as COM+, have fallen out of favor, such as COM+; however, others, such as BizTalk, remain both popular and powerful. When new tools are released, it’s always natural to look at them and try to determine where they fit. It’s important for you to determine whether they are replacement or complementary technologies. As you perform your analysis and make your comparisons, remember that Alan Kay once said that perspective is worth 80 IQ points. We, the authors, hope that reading this book will give you a solid understanding of where you can utilize AppFabric in the middle tier. We also hope it will help you understand when you should utilize AppFabric rather than other technologies.