Groovy and Grails

The collection of a comprehensive Groovy and Grails framework tutorial (Grails 3 and 4) based on the experience and research of this blog author. If you heard or use Ruby on Rails then Groovy on Grails is another name for this framework with the same simplification of use and learning.

What is Groovy?

Groovy is a simple programming language that simplified the complexity of Java programming language. It is run on the same JVM as Java. Groovy uses a curly-bracket syntax similar to Java's. Groovy supports closures, multiline strings, and expressions embedded in strings. Much of Groovy's power lies in its AST (Abstract syntax tree) transformations, triggered through annotations.

Why should I learn Groovy?

Because it's an easier than Java with the same robust and enterprise-class programming language. If you like to learn Java but worried about complexity or a lot of learning curves then Groovy is the best choice to learn. Groovy simplified the complexity in Java, almost a lot of Java with a long code can be done with just shorter Groovy code. For example, the loops using "For" keyword.

Java:

for(int i = 0; i <= 10; i++) {
  System.out.println(i);
}

Groovy:

for(i in 0..10) {
  println i
}

As you can see in the above example, Groovy has removed the complexity of Java coding styles.

Here they are the core features of Groovy Language:

• Flat learning curve: Concise, readable and expressive syntax, easy to learn for Java developers
• Smooth Java integration: Seamlessly and transparently integrates and interoperates with Java and any third-party libraries
• Vibrant and rich ecosystem: Web development, reactive applications, concurrency / asynchronous / parallelism library, test frameworks, build tools, code analysis, GUI building
• Powerful features: Closures, builders, runtime & compile-time meta-programming, functional programming, type inference, and static compilation
• Domain-Specific Languages: Flexible & malleable syntax, advanced integration & customization mechanisms, to integrate readable business rules in your applications
• Scripting and testing glue: Great for writing concise and maintainable tests, and for all your build and automation tasks

What is Grails Framework?

Grails is a powerful Groovy-based web application framework for the JVM built on top of Spring Boot. It uses convention-over-configuration, sensible defaults, opinionated APIs, and the Groovy language combine to make Grails easy to learn for Java developers. Its also seamlessly and transparently integrates and interoperates with Java, the JVM, and existing Java EE containers.

Why should I learn Grails Framework?

As we describe in the first paragraph that Grails Framework is similar to Ruby on Rails with the name Groovy on Grails. So, building a web application with an enterprise standard is really simple and easier than using plain Java. Almost all required plugin, libraries or modules that used in the Industry are ready for Grails Framework. By that, you can keep focused on the logic than thinking on how to create this and that because it's already done by the plugins, libraries or modules.

Here they are the core features of Grails Framework:

• Flat learning curve: Convention-over-configuration, sensible defaults, opinionated APIs, and the Groovy language combine to make Grails easy to learn for Java developers.
• On top of Spring Boot: Grails is built on top of Spring Boot and leverages Spring Boot's time-saving features, such as Spring-powered dependency injection.
• Smooth Java Integration: Grails seamlessly and transparently integrates and interoperates with Java, the JVM, and existing Java EE containers.
• Groovy-based: Apache Groovy is a language for the Java platform designed to enhance developers' productivity. It is an optionally-typed and dynamic language but with static-typing and static compilation capabilities.
• Seamless GORM Integration: Grails seamlessly integrates with GORM, a data access toolkit that provides a rich set of APIs for accessing relational and non-relational data. GORM also includes implementations for Hibernate (SQL), MongoDB, Cassandra, and Neo4j.
• REST APIs, React, Angular: With the use of application profiles, including React and Angular, Grails allows developers to build REST APIs or modern web applications with a JavaScript frontend.
• Plugins: Developers can build plugins that extend and enhance Grails, or they can access existing plugins published by a vibrant plugin community.
• View Technologies: Technologies such as GSP, JSON Views, and Markup Views help developers effortlessly generate HTML, JSON, and XML.
• Asynchronous capabilities: The async features of Grails aim to simplify concurrent programming. Grails' features include the concept of Promises, a unified event model, and the use of RxJava to write reactive logic.
• Open source: Grails is an Open Source Apache 2 License project.
• Domain-specific languages: Grails relies on expressive domain-specific languages (DSLs) for validation, querying, markup rendering, and more.
• IDE Supports: Developers can access support at any time via IDEs and text editors, such as Intellij IDEA, Eclipse, Sublime, and Textmate.