Java Magazine - Premiere Issue 2011

Introduction to RESTful
Web Services
Extend or add functionality into your applications with RESTful Web services.
MAX BONBHEL

JAVA IN ACTION

This article, the first of a three- part series, demonstrates how to create a Java Platform, Enterprise Edition (Java EE) application integrating Representational State Transfer (REST) Web services. I will use the NetBeans 6. 9. 1 IDE and Java EE 6 to create the application and Oracle GlassFish Server 3. 1 to deploy it.

Part 2 (coming in the next issue) covers managing the answers sent by a Web service using the JavaScript Object Notation (JSON) framework, while Part 3 focuses on the integration of Java API for XML Web Services (JAX-WS). These articles highlight methods for increasing application agility.

with other systems via Hyper Text Transfer Protocol (HTTP) using Extensible Markup Language (XML). Web services allow you to mask the complexity of each application included in the exchange and achieve complex operation.

Web services are more than the sum of the technologies used to deploy an application. They are a method for carving out services from business functionalities that are then exposed to be consumed by client applications.

ers and the consumers of the services. And RESTful Web services provide support for a variety of message formats (XML, JSON, HTML, and more).

■ ■ RESTful Web services are easy to integrate into existing applications in order to extend or add new functionality.

REST is just an architectural style, not a technology. That is why there is a specification, JSR- 311, to describe how REST should be implemented in Java. There have been several implementations of this standard. Jersey is the official reference implementation and the one that is most widely used in development and production. Jersey is open source and backed by Oracle.

However, REST might have some limitations when it comes to “big” Web services. This will be discussed in Part 3 of the series.

scribed in this article:

■ ■ NetBeans IDE. Download here.
■ ■ Jersey (included in NetBeans):
It is the open source, produc-
tion-quality reference imple-
mentation for a Java EE speci-
fication (JAX-RS JSR-311) for
building RESTful Web services.

Note: This article was tested using NetBeans IDE 6. 9. 1; as of this writing, the latest version is NetBeans IDE 7.0.

ABOUT US

What Are Web Services? Web services provide a standard means of interoperating among software applications that run on a variety of platforms or frameworks. In other words, Web services are the best and standard way to extend your application in order to make it interoperable

Why RESTful Web Services?

Java EE 6 provides natively all mechanisms for REST via the “Java API for RESTful Web Services” (JAX-RS), JSR-311. There are many good reasons to choose REST to add the Web services into your system. Here are some examples:

■ ■ The most important reason is that RESTful Web services are easy to learn, easy to build, and easy to deploy.

■ ■ REST provides a uniform interface between the produc-

Real-Life Application

In this practical section, we will build a real-life application step by step so that you can learn quickly the basics of the RESTful Web services.

The application is an online auction place (like eBay). Sellers post their items in listings, and buyers bid on the items. A seller can post one or many items, and a buyer can bid on one or many items. To simplify, we will consider the following entities: Seller, Item, and Bid.