Grails are an advanced and innovative web framework built upon the considerable success of Groovy and the development of other, powerful open-source tool kits. It builds on the simplicity, and power of Groovy as a language and it is based upon the concept of “convention over configuration”, which made Ruby popular in among other languages.

Another notable feature of Groovy is its ability to reuse so much functionality from Java, which after all is not going anywhere in the immediate future. Well-known and frequently-used tools like Hibernate, Spring, SiteMesh, Quartz are often combined to produce applications. Though each of them has a crucial learning curve on its own, by combining them in a standard way and at a far simpler level of abstraction, Grails, flattens the curve.

Grails, which aims to bring the “coding by convention” paradigm to Groovy, is an open-source web application framework that leverages the Groovy language and complements the Java Web development. Grails have been licensed under the liberal Apache 2.0 Software License.

Grails is rapid as it does the web2.0 project within weeks instead of months. It also delivers a new age of Java web application productivity. Grails are Dynamic in the sense, we Get instant feedback and can see instant results and Grails are the premier, dynamic language web framework for the JVM. Grails are robust, and it out performs the competition. It is a dynamic, agile web development without compromises and is powered by spring.

Groovy is the leading open source dynamic language for the JVM that offers a flexible syntax similar to Java that most Java developers can learn in no time. Groovy provides features of other dynamic languages like Ruby, Python or Smalltalk. Groovy shines in its ability to fix easily internal Domain Specific Languages (DSLs) that can be used as an abstraction layer which enables non-technical, subject matter experts to codify business rules. The combination of Groovy and Grails offers productivity benefits rivaling Ruby on Rails, but on the proven, scalable, and seamlessly integrated Java platform. SpringSource offers a support agreement for Groovy and Grails that provide the expert developer and production support, and legal indemnification businesses need to confidently deploy Groovy and Grails technologies across the enterprise.

To start using Grails, you need to have an installation of Java SDK 1.4 or higher. You will have to set your JAVA_HOME variable to the SDK install location. If you are trying to use grails from Git, you need An installation of Java 1.5 or higher and have to set your JAVA_HOME variable to the install location. It also need a working installation of Apache Ant 1.7 or higher and a JUnit (to run the build tests – put junit.jar in your ANT_HOMElib directory) and a Git client.