WAS v8.5 > End-to-end paths > Web services - RESTful services

Implement RESTful views of EJB applications using JAX-RS

If we have enterprise JavaBeans (EJB) applications, we can expose a RESTful interface to the enterprise bean using Java API for RESTful Web Services (JAX-RS). By implementing JAX-RS annotated enterprise beans, you keep the EJB functionality including transaction support, injection of Java EE components and resources, and other EJB session bean capabilities.

Before EJB 3.1, enterprise beans that required an EJB local client view also needed a separate Java interface, usually located in a separate file, that declared the local view methods. The enterprise bean specified that it implemented the EJB local view interface using deployment descriptors or EJB annotations.

Using the EJB 3.1 specification, we have the option of exposing a local view of an enterprise bean without an explicit EJB local interface. Instead, the enterprise bean has a no-interface client view based on the public methods of your bean class. No-interface view enterprise beans can be more simple to develop than a local view enterprise bean for the following reasons:

• No-interface view enterprise beans do not require a separate Java interface declaration
• No-interface view enterprise beans do not require specifying additional metadata in the deployment descriptor or when using annotations

See the EJB 3.1 specification for more details on the no-interface views of an enterprise bean.

JAX-RS supports the use of enterprise beans that declare a local business interface and no-interface view enterprise beans.

Procedure

1. Configure the development environment
   • Set up a development environment for JAX-RS applications
     
   • Development and assembly tools
     
   • Directory conventions
     

2. Define the resources in JAX-RS web applications

   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.

   • Define the resources in RESTful applications
     
   • Define the URI patterns for resources in RESTful applications
     
   • Define resource methods for RESTful applications
     
   • Define the HTTP headers and response codes for RESTful applications
     
   • Define media types for resources in RESTful applications
     
   • Define parameters for request representations to resources in RESTful applications
     
   • Define exception mappers for resource exceptions and errors
     

3. Configure the JAX-RS application

   We can configure JAX-RS applications in multiple ways depending on your needs. 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 v1.1 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. You might want to use this method when we do not want 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 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 your JAX-RS application:

   • Configure JAX-RS applications using JAX-RS 1.1 methods
   • Configure web.xml for JAX-RS servlets
   • Configure web.xml for JAX-RS filters

4. Implement RESTful views of enterprise beans

   We can implement RESTful views of enterprise beans using JAX-RS for a stateless or singleton enterprise bean that uses a no-interface view or a local business interface.

   • Implement RESTful views of a no-interface EJB
   • Implement RESTful views of an EJB with local interfaces

5. Assemble JAX-RS web applications

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

   • Assemble JAX-RS web applications
     
   • Development and assembly tools
     

6. Deploy JAX-RS web applications
   Deploy JAX-RS web applications

   After we have assembled your JAX-RS web application, you need to deploy the web archive (WAR) package or the EAR package onto the application server.

Related

Implement RESTful views of a no-interface EJB
Implement RESTful views of an EJB with local interfaces
Develop a session bean to have a No-Interface Local view
Develop singleton session beans
Web services specifications and APIs
EJB application specifications and APIs

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