Web services are something new for me. I’ve heard all about them and the popularity of them, but taking the task upon myself to create one was something that I’d never done. The WSDLs looked somewhat complicated and I just had no motivation until yesterday. However, to my surprise, I found that the process is not really too complicated at all. In this article I’ll show you how to make a simple web service that adds and multiplies.
The Webservice
//MathExampleImpl.java -- WebService Example by Jason Staten
package com.jstaten.webService.server;
import javax.jws.WebMethod;
import javax.jws.WebService;
@WebService
public class MathExampleImpl {
@WebMethod(operationName="addInts")
public int addInts(int a, int b)
{
return a + b;
}
@WebMethod(operationName="multiplyFloats")
public float multiplyFloats(float a, float b)
{
return a * b;
}
}
The service is very straightforward. Essentially you create a class with the operations that will show up in the WSDL. This class has two, addInts and multiplyFloats which will add integers and multiply floats, respectively. The annotations @WebService and @WebMethod are later parsed when building this application.
The Server
//MathService.java -- WebService Example by Jason Staten
package com.jstaten.webService.server;
import javax.xml.ws.Endpoint;
public class MathService {
private Endpoint endpoint = null;
public MathService()
{
endpoint = Endpoint.create(new MathExampleImpl());
}
private void publish()
{
endpoint.publish("http://localhost:7070/MathExample/MathService");
}
public static void main(String[] args)
{
MathService hws = new MathService();
hws.publish();
System.out.println("Waiting");
}
}
The server relies on one key component, the Endpoint class. Endpoints are used to publish a webservice to a specific address. In this very simple example, we take a new instance of our MathExampleImpl class that we created earlier and publish it to http://localhost:7070/MathExample/MathService which will be where we direct any webservice calls to from a client. Finally, we give the “Waiting” message to know that the server has started and is waiting for a connection.
The Build File
<?xml version="1.0" encoding="UTF-8"?>
<!--build.xml WebService Example by Jason Staten-->
<project basedir="." default="build-server" name="MathServiceExample">
<property environment="env"/>
<property name="lib.home" value="${env.JAXWS_HOME}/lib"/>
<property name="build.home" value="${basedir}/build"/>
<property name="build.classes.home" value="${build.home}/classes"/>
<path id="jaxws.classpath">
<pathelement location="${java.home}/../lib/tools.jar"/>
<fileset dir="${lib.home}">
<include name="*.jar"/>
<exclude name="j2ee.jar"/>
</fileset>
</path>
<taskdef name="apt" classname="com.sun.tools.ws.ant.Apt">
<classpath refid="jaxws.classpath"/>
</taskdef>
<target name="setup">
<mkdir dir="${build.home}"/>
<mkdir dir="${build.classes.home}"/>
</target>
<target name="build-server" depends="setup">
<apt
fork="true"
debug="true"
verbose="${verbose}"
destdir="${build.classes.home}"
sourcedestdir="${build.classes.home}"
sourcepath="${basedir}/src">
<classpath>
<path refid="jaxws.classpath"/>
<pathelement location="${basedir}/src"/>
</classpath>
<option key="r" value="${build.home}"/>
<source dir="${basedir}/src">
<include name="**/server/*.java"/>
<include name="**/common/*.java"/>
</source>
</apt>
</target>
<target name="clean">
<delete dir="${build.home}" includeEmptyDirs="true"/>
</target>
The build file is where a lot of the magic is done. At first glace it may seem a little confusing, but broken down, it is actually quite simple. Lets step through it.
<property environment="env"/>
<property name="lib.home" value="${env.JAXWS_HOME}/lib"/>
<property name="build.home" value="${basedir}/build"/>
<property name="build.classes.home" value="${build.home}/classes"/>
The first section is properties that will be used throughout the rest of the build file describing the location of JAX-WS and the location to place compiled files.
<path id="jaxws.classpath">
<pathelement location="${java.home}/../lib/tools.jar"/>
<fileset dir="${lib.home}">
<include name="*.jar"/>
<exclude name="j2ee.jar"/>
</fileset>
</path>
This section defines the classpath of JAX-WS for usage within the build file.
<taskdef name="apt" classname="com.sun.tools.ws.ant.Apt">
<classpath refid="jaxws.classpath"/>
</taskdef>
Within this element, we declare apt which is what does the actual parsing of the annotations within your source files. We will use it as an element later on in the build file.
<target name="build-server" depends="setup">
<apt
fork="true"
debug="true"
verbose="${verbose}"
destdir="${build.classes.home}"
sourcedestdir="${build.classes.home}"
sourcepath="${basedir}/src">
<classpath>
<path refid="jaxws.classpath"/>
<pathelement location="${basedir}/src"/>
</classpath>
<option key="r" value="${build.home}"/>
<source dir="${basedir}/src">
<include name="**/server/*.java"/>
<include name="**/common/*.java"/>
</source>
</apt>
</target>
The build-server target is the main operation within the build file. It utilizes apt like we declared earlier and tells it where to place the compiled code as well as the generated source. Using the properties we declared earlier, we can essentially just fill in the blanks. destdir is the location of the compiled code, sourcedestdir is the placement of generated source code(from parsing the attributes), and sourcepath is the path to the source files that you created earlier.
<target name="clean">
<delete dir="${build.home}" includeEmptyDirs="true"/>
</target>
Finally, the clean target removes old compiled code. This can be run by using ant clean
After compiling a simple java com.jstaten.webService.server.MathService will start the server and a quick pointing of your browser to http://localhost:7070/MathExample/MathService?wsdl will result in receiving a WSDL.
In a later article I will discuss the creation of a client to use this service a within both Java and C#.
