Smith G., Ledbrook P. Grails in Action 2ed 2014

Textbook in PDF format

Grails in Action, Second Edition is a comprehensive introduction to Grails 2 focused on making you super-productive fast. In this totally revised new edition, you'll master Grails 2.3 core skills as you apply TDD techniques to developing a full-scale Twitter clone. Along the way you'll learn the latest single-page web app UI techniques, work with NoSQL backends, integrate with enterprise messaging, and implement a complete RESTful API for your services.
It may be time for you to stop reconfiguring, rewriting, and recompiling your Java web apps. Grails, a Groovy-powered web framework, hides all that busy work so you can concentrate on what your applications do, not how they're built. In addition to its famously intuitive dev environment and seamless integration with Spring and Hibernate, the new Grails 2.3 adds improved REST support, better protection against attacks from the web, and better dependency resolution