Implement JAX-RS web applications

Use Java API for RESTful Web Services (JAX-RS) to develop services that follow Representational State Transfer (REST) principles. Using JAX-RS, development of RESTful services is simplified.

JAX-RS capabilities are provided by the use of a servlet or a filter. When we configure the web.xml file of our web application and assemble the IBM JAX-RS implementation based on the Apache Wink framework into the library directory of our web application, the business application is now ready to use JAX-RS capabilities.

To implement JAX-RS web appliations, proceed with the following steps:

Tasks

1. Configure the development environment.

   1. Before starting developing JAX-RS applications, we must set up the development environment by adding the JAX-RS libraries to the classpath.

2. Define the resources in JAX-RS web applications.
   1. Resources are the basic building block of a RESTful service. Resources can contain static or dynamically updated data. Examples of resources from an online book store application include a book, an order from a store, and a collection of users. By identifying the resources in the application, we can make the service more useful and easier to develop.

3. Configure the JAX-RS application.

   We can configure JAX-RS applications in multiple . To take advantage of the Java EE 6 functionality, we can use the annotation scanning capabilities. By using annotation scanning, we can omit a JAX-RS javax.ws.rs.core.Application subclass or have a minimally defined javax.ws.rs.core.Application subclass. Alternatively, we can specify the IBM JAX-RS servlet or filter to use the functionality available in the IBM JAX-RS servlet and filter.

   Using one of the JAX-RS Version 1.1 configuration methods, we can omit a javax.ws.rs.core.Application subclass in the application or have a javax.ws.rs.core.Application subclass that returns an empty set of classes to inform the JAX-RS runtime environment to find and use all the JAX-RS classes in the application. We might want to use this method when we do not want to have to manually add every relevant JAX-RS class to a javax.ws.rs.core.Application subclass as you develop the application.

   By specifying the specific IBM JAX-RS servlet and filter, we can take advantage of and ensure specific IBM JAX-RS behavior. For example, using the IBM JAX-RS filter can be helpful in developing a web application with a mix of JAX-RS resources and JSP files with the same URL patterns.

   Even though there is a JAX-RS V1.1 configuration method that supports the use of an optional web.xml file, to specify security constraints or roles, or we want to take advantage of other features enabled using a web.xml file, specify the information in a web.xml file.

   Choose one of the following three methods to configure the JAX-RS application:

   • Configure JAX-RS applications using JAX-RS 1.1 methods

     Use this method to use the annotation scanning capabilities or to use the JAX-RS 1.1 configuration methods. Use the annotation scanning capabilities to promote application portability, to minimize the amount of configuration code, or to dynamically modify the application without changes to the application code.

   • Configure the web.xml file for JAX-RS servlets

     Use this method to specify features enabled using servlet initialization parameters to change the behavior and ensure that we get the IBM JAX-RS servlet. When using servlets, we can define a servlet path in the web.xml file that is appended to the base URL.

   • Configure the web.xml file for JAX-RS filters

     Use this method to use the filter when we have JSPs, other servlets and filters, and JAX-RS resources with a mix of URL patterns. We can configure the web.xml file to define filters that indicate the possible URLs on which the filter can be invoked.

4. Assemble JAX-RS web applications.

   1. After developing the Java class files for our JAX-RS web application and edit the web.xml file to enable the JAX-RS servlet, we are ready to assemble the application. Assemble the web application into a web application archive (WAR) package. We can assemble the WAR package into an enterprise archive (EAR) package, if required.

5. Deploy JAX-RS web applications.

   1. After assembling the JAX-RS web application, we need to deploy your Web archive (WAR) package or the EAR package onto the application server.

We have developed and deployed a JAX-RS web application on the application server.

Related:

Overview of IBM JAX-RS

Planning to use JAX-RS to enable RESTful services

Web services specifications and APIs