REST type gives you a lot of flexibility. This is how to create the server and the corresponding client using Apache CXF.
Prerequisites
You should have installed:- Sun Java 6
- Maven 3
Creating a REST based Webservice
1) On Maven pom.xml please include:<packaging>war</packaging>
<properties>
<cxf.version>2.6.0</cxf.version>
<spring.version>3.0.5.RELEASE</spring.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-rt-transports-http</artifactId>
<version>${cxf.version}</version>
<scope>runtime</scope>
</dependency>
<!-- REST based WS: Required libraries during compile time since Java 6
doesn't include REST specification libraries. -->
<dependency>
<groupId>org.apache.servicemix.specs</groupId>
<artifactId>org.apache.servicemix.specs.jsr311-api-1.1</artifactId>
<version>1.6.0</version>
</dependency>
<dependency>
<groupId>org.apache.servicemix.specs</groupId>
<artifactId>org.apache.servicemix.specs.jaxb-api-2.1</artifactId>
<version>1.6.0</version>
</dependency>
<!-- REST based WS: Required libraries. In OSGi environment, these may be provided -->
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-rt-frontend-jaxrs</artifactId>
<version>${cxf.version}</version>
<scope>runtime</scope>
</dependency>
</dependencies>
2) Create an interface defining a webservice
The primary annotations for SOAP based WS are: @Path, @Produces and a group defining the REST methods (@POST, @PUT, etc)
import javax.ws.rs.FormParam;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
@Path("/calculator") // REST based WS: Path of this resource (or service)
@Produces({"application/xml", "application/json"}) // REST based WS: Response format
public interface CalculatorService {
@POST // REST based WS: Called using POST method
@Path("/sum") // REST based WS: Path of a sub resource
public int sum(
@FormParam(value = "a") // REST based WS: Define a form parameter (http://uri.com/sum?a=2)
int a,
@FormParam(value = "b")
int b);
@POST
@Path("/algorithm/{code}")
public Data process(
@PathParam("code") // REST based WS: This argument is taken from a path
String dCode,
Data dData);
}
3) Add XML annotations for complex object
Default constructor is mandatory!!!
@XmlRootElement(name = "data")
public class Data {
@XmlElement(name = "entry")
public Collection getEntries() {
return entries;
}
public void setEntries(Collection entries) {
this.entries = entries;
}
}
@XmlRootElement
public class FieldEntry {
// Create setter getter methods for 'field' and 'value'
}
4) Create the implementation
public class MyCalculatorServiceImpl implements CalculatorService
5) Create Spring context files
Inside resources directory (src/main/resources) create context files:
5.1) META-INF/spring/application-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="calculatorService"
class="michsan.research.cxf.wsserver.impl.MyCalculatorServiceImpl" />
</beans>
5.2) META-INF/spring/ws-context.xml (Watch for namespace!)
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xmlns:jaxrs="http://cxf.apache.org/jaxrs"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd">
<import resource="classpath:META-INF/cxf/cxf.xml" />
<!-- REST based WS and SOAP based WS: Required -->
<import resource="classpath:META-INF/cxf/cxf-extension-*.xml" />
<!-- if (Simple Web Application) { -->
<import resource="classpath:META-INF/cxf/cxf-servlet.xml"/>
<!-- } -->
<!-- REST based WS: Root context -->
<jaxrs:server id="wsServiceRoot" address="/rest">
<jaxrs:serviceBeans>
<ref bean="calculatorService" />
</jaxrs:serviceBeans>
<jaxrs:extensionMappings>
<entry key="xml" value="application/xml" />
<entry key="json" value="application/json" />
</jaxrs:extensionMappings>
</jaxrs:server>
</beans>
6) Create web.xml file
In src/main/webapp/WEB-INF/web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<display-name>CXF Calculator Service</display-name>
<description>Learning how to create CXF Webservice server</description>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath*:META-INF/spring/*-context.xml</param-value>
</context-param>
<!-- Creates the Spring Container shared by all Servlets and Filters -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
<servlet-name>cxfServlet</servlet-name>
<servlet-class>org.apache.cxf.transport.servlet.CXFServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>cxfServlet</servlet-name>
<url-pattern>/ws/*</url-pattern>
</servlet-mapping>
</web-app>
7) Deploy (or mvn tomcat:run)
8) See it running in http://localhost:8080/cxf-ws-server/ws
Consuming the REST based Webservice
1) On Maven pom.xml<dependencies>
<dependency>
<artifactId>cxf-rt-frontend-jaxrs</artifactId>
<groupId>org.apache.cxf</groupId>
<version>2.6.0</version>
</dependency>
</dependencies>
2) Understand how to invoke the service.
Usually the service provider gives you a page describing how to use the service. If this is the case: Data sent and received is in the following format
<data>
<entry>
<field>name</field>
<value>JACK</value>
</entry>
<entry>
<field>cif</field>
<value>343434</value>
</entry>
</data>
Next, you must use complex object Data (see previous post)
3) On static main:
Given that center of all REST services is on http://localhost:8080/cxf-ws-server/ws/rest and the exact REST resource is on calculator/algorithm/{NAME_OF_ALGORITHM} using POST method and XML format, then in main method:
String baseUri = "http://localhost:8080/cxf-ws-server/ws/rest";
WebClient client = WebClient.create(baseUri);
client.accept("application/xml");
// Service 1 ------------------------------
client.reset().path("calculator/sum");
Form form = new Form();
form.set("a", 4);
form.set("b", 9);
Response response = client.form(form);
if (response.getStatus() == 200) { // OK
InputStream inStream = (InputStream) response.getEntity();
BufferedReader reader = new BufferedReader(new InputStreamReader(
inStream));
System.out.println(reader.readLine());
reader.close();
}
// Service 2 ------------------------------
client.reset().path("calculator/algorithm/INTEGRAL");
Data requestData = new Data();
requestData.add("arg1", "5");
requestData.add("arg2", "8");
Data responseData = client.post(requestData, Data.class);
// Print a response value
System.out.println(responseData.getEntries().iterator().next().getValue());
For testing the WS:
http://niftybits.wordpress.com/2009/08/26/recipe-unit-testing-apache-cxf-restful-services/
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