Java tools and frameworks for building RESTful web services

Over the last few years, the REST architectural style has become very popular in the industry and many enterprises have accepted it as the current standard for building public web APIs, particularly when scalability and simplicity are major concerns for them. Today, one may see many tools and frameworks available on the market for building RESTful web services. In this section, we will briefly discuss some of the most popular Java-based frameworks and tools for building RESTful systems.

The Java API for RESTful web services (JAX-RS) is the Java API for creating RESTful web services following the REST architectural pattern discussed in this chapter. JAX-RS is a part of the Java Platform Enterprise Edition (Java EE) platform and is designed to be a standard and portable solution. There are many reference implementations available for JAX-RS today. Some of the most popular implementations are Jersey, Apache CXF, RESTEasy, and Restlet. At this juncture, it is worth mentioning that most of the frameworks in the preceding list, such as Jersey and Apache CXF, are not just limited to reference implementations of the JAX-RS specifications, but they also offer many additional features on top of the specifications.

Apart from the JAX-RS-based frameworks (or extensions built on top of JAX-RS), you may also find some promising nonstandard (not based on JAX-RS) Java REST frameworks on the market. Some such frameworks are as follows:

• One such framework is RESTX, which is an open source Java REST framework and is primarily focused on the server-side REST API development. This is relatively new on the market and simplifies the REST API development.
• Spark is another framework that falls into this category. It is a Java web framework with support for building REST APIs. Spark 2.0 is built using Java 8, leveraging all the latest improvements of the Java language.
• Play is another framework worth mentioning in this category. It is a Java (and Scala)-based web application framework with inherent support for building RESTful web services.

Discussing all these frameworks does not come under the scope of this book. We will focus on some of the most popular frameworks with many real-life use cases in mind. In the next chapters, you will learn JAX-RS as well as additional features available with the Jersey framework for building scalable and maintainable RESTful web services.