Modular Java – Creating Flexible Applications with OSGi and Spring by Craig Walls (Pragmatic Bookshelf)
This book makes it easy to understand the concept of component-level modularity and how it can be achieved and better managed through the capabilities of OSGi and Spring Dynamic Modules (Spring-DM). Walking you through a sufficiently complex example, the book not only provides how-to’s but also teaches valuable concepts. The author’s style is to introduce the detailed underpinnings of the functionality and, then, show how things can be done more easily with companion technologies. It’s a quick read and a valuable reference guide!