JSR 311 (http://jcp.org/en/jsr/detail?id=311) specifies the Java API for RESTful Web services (JAX-RS) for developing REST (Representational State Transfer) Web services with Java. REST is a protocol independent, loosely coupled, software architecture style for distributed systems. A RESTful Web service exposes a set of resources, which are simply sources of information, identified by URIs (Uniform Resource Identifiers) in HTTP. RESTful Web services follow these RESTful principles:
- Every resource has a unique base URI
- For invoking Web service operations, the HTTP protocol methods such as
GET,PUT,POST, andDELETEare used - A client sends a request to a service, and the service returns a representation of a resource requested to the client
- Client sessions are not stored on the server, which makes it easier to scale the service with less data to replicate in a clustered environment
JSR 339 (https://www.jcp.org/en/jsr/detail?id=339) develops the JAX-RS 2.0 version. JAX-RS 2.0 provides several new features, such as a Client API, support for validation, filters and interceptors, and asynchronous processing. We will discuss the salient new features in JAX RS 2.0 using the RESTEasy (http://resteasy.jboss.org/) implementation. This chapter has the following sections:
- Setting up the environment
- The Client API
- Filters and interceptors
- Asynchronous processing
- Cancelling a request
- Session bean EJB resource
- Making an asynchronous call from the client
We need to install the following software:
- WildFly 8.1.0.Final: Download
wildfly-8.1.0.Final.zipfrom http://wildfly.org/downloads/. - Eclipse IDE for Java EE Developers: Download Eclipse Luna from https://www.eclipse.org/downloads/packages/release/Luna/SR1.
- JBoss Tools (Luna) 4.2.0.Final (or the latest version): Install this as a plugin to Eclipse from Eclipse Marketplace (http://tools.jboss.org/downloads/installation.html).
- Apache Maven: Download version 3.05 or higher from http://maven.apache.org/download.cgi.
- Java 7: Download Java 7 from http://www.oracle.com/technetwork/java/javase/downloads/index.html?ssSourceSiteId=ocomcn.)
Set the environment variables JAVA_HOME, JBOSS_HOME, and MAVEN_HOME. Add %JAVA_HOME%/bin, %MAVEN_HOME%/bin, and %JBOSS_HOME%/bin to the PATH environment variable.
Create a WildFly 8.1.0 runtime as discussed in Chapter 1, Getting Started with EJB 3.x. Create a MySQL data source with the JNDI name java:jboss/datasources/MySQLDS as explained in Chapter 1, Getting Started with EJB 3.x.