Processing Request/Response Messages of a Web Service Using Handler Chain

Here is the ant script build.xml to package the EAR. Note that Web.xml and application.xml should be available before building the EAR.

build.xml

<project name="webservices-handler" default="all" basedir="."><!--  set global properties for this build  --><property environment="env" /><property name="compiler" value="modern" /><property name="debug" value="yes" /><property name="deprecation" value="yes" /><property name="build.compiler" value="${compiler}" /><property name="source" value="." /><property name="build" value="${source}/build" /><property name="war_file" value="BalanceEnquiry.war" /><property name="ear_file" value="BalanceEnquiry.ear" /><property name="namespace" value="http://www.bea.com" /><property name="client.classes.dir" value="{source}/clientclasses" /><target name="all" depends="clean, war, ear" /><target name="clean"><delete dir="${build}" /><delete file="${source}/${ear_file}" /><delete file="${war_file}" /></target><target name="war"><delete dir="${build}" /><mkdir dir="${build}" /><mkdir dir="${build}/WEB-INF" /><mkdir dir="${build}/WEB-INF/classes" /><javac srcdir="${source}" includes="AuthenticationHandler.java,                          BalanceEnquiryService.java"                          destdir="${build}/WEB-INF/classes" /><copy todir="${build}/WEB-INF"><fileset dir="${source}"><include name="web-services.xml" /><include name="web.xml" /></fileset></copy><jar jarfile="${war_file}" basedir="${build}" /></target><target name="ear" depends="war"><delete dir="${build}" /><mkdir dir="${build}" /><mkdir dir="${build}/META-INF" /><copy todir="${build}"><fileset dir="${source}"><include name="${war_file}" /></fileset></copy><copy todir="${build}/META-INF"><fileset dir="${source}"><include name="application.xml" /></fileset></copy><jar jarfile="${source}/${ear_file}" basedir="${build}" /></target></project>

The ant script creates a WAR and then packages the EAR.

Deploy the generated EAR in Weblogic server. The following is the client to invoke the BalanceEnquiryService.

Client.java

import org.apache.axis.client.Call;import org.apache.axis.client.ServiceFactory;import org.apache.axis.client.Service;import org.apache.axis.MessageContext;import org.apache.axis.attachments.Attachments;import org.apache.axis.message.SOAPEnvelope;import javax.xml.namespace.QName;import javax.xml.soap.SOAPBody;import javax.xml.soap.SOAPBodyElement;import javax.xml.soap.SOAPConnection;import javax.xml.soap.SOAPConnectionFactory;import javax.xml.soap.SOAPElement;import javax.xml.soap.SOAPHeader;import javax.xml.soap.SOAPHeaderElement;import javax.xml.soap.SOAPMessage;import javax.xml.soap.SOAPPart;import javax.xml.namespace.QName;import javax.xml.rpc.ParameterMode;import javax.xml.soap.AttachmentPart;import javax.xml.soap.MessageFactory;import javax.xml.soap.Name;import javax.xml.rpc.ParameterMode;import java.net.URL;import java.util.Iterator;public class Client{   private static String TARGET_NAMESPACE = "http://www.bea.com";   private static QName xsdFloat = new                  QName("http://www.w3.org/2001/XMLSchema", "float");   public static org.apache.axis.message.SOAPEnvelope env = null;   public static SOAPMessage message = null;   public static void main(String[] argv) throws Exception   {      Client client = new Client();      env = client.constructSOAPEnvelope();      client.constructHeader(env);      client.constructBody(env);      System.setProperty( "javax.xml.rpc.ServiceFactory",                          "org.apache.axis.client.ServiceFactory" );      String url =     "http://localhost:7001/BalanceEnquiry/BalanceEnquiryService";     ServiceFactory factory =         (org.apache.axis.client.ServiceFactory)ServiceFactory.              newInstance();      QName serviceName   = new QName(TARGET_NAMESPACE,         "BalanceEnquiryService");      Service service =          (org.apache.axis.client.Service)factory.          createService(serviceName);      Call call = (org.apache.axis.client.Call)service.createCall();      call.setTargetEndpointAddress(url);      SOAPEnvelope result = call.invoke(env);      System.out.println(result);   }   public SOAPEnvelope constructSOAPEnvelope() throws Exception   {      org.apache.axis.message.SOAPEnvelope env = new         org.apache.axis.message.SOAPEnvelope();      return env;   }   public void constructHeader(SOAPEnvelope envelope) throws Exception   {      SOAPHeader header = envelope.getHeader();      Name headerElementName =         envelope.createName("AccountDetails","",                             "http://schemas.xmlsoap.org/soap/                                     envelope/");      SOAPHeaderElement headerElement =         header.addHeaderElement(headerElementName);      headerElement.setMustUnderstand(false);      headerElement.addNamespaceDeclaration("soap",         "http://schemas.xmlsoap.org/soap/envelope/");      SOAPElement accNo = headerElement.addChildElement("accountNo");      accNo.addTextNode("12345");      SOAPElement pinNo = headerElement.addChildElement("pin");      pinNo.addTextNode("6789");   }   public void constructBody(SOAPEnvelope envelope) throws Exception   {      SOAPBody body = envelope.getBody();      Name bodyRootElementName =         envelope.createName("getBalance","",                             "http://schemas.xmlsoap.org/soap/                                     encoding/");      SOAPBodyElement bodyRootElement =         body.addBodyElement(bodyRootElementName);      SOAPElement bodyElement =         bodyRootElement.addChildElement("param0");      bodyElement.addAttribute(envelope.createName("xsi:type"),                                                   "xsd:string");      bodyElement.addTextNode("12");   }}

If there is a client side handler available, make the following changes:

1. Import the following two classes.

   import javax.xml.rpc.handler.HandlerInfo;import javax.xml.rpc.handler.HandlerRegistry;

2. Include the following lines before call.invoke().

   QName portName = new QName( "http://bea.com/",                             "HelloWorldServicePort");HandlerRegistry registry = service.getHandlerRegistry();List handlerList = new ArrayList();handlerList.add( new HandlerInfo( ClientHandler.class, null,                 null ) );registry.setHandlerChain( portName, handlerList );

Conclusion

We hope this article helps you understand more about the the Handler chain mechanism and its usage in Web Services.

About the Authors

Nandhini Arumugam holds a Masters degree in Computer Applications from PSG College of Technology, Coimbatore. She has been working as a software engineer in the Telecom and Mobile Solutions Lab, Hewlett-Packard, Bangalore for more than one year. The domain of her experience includes Web Services and J2EE-related technologies. She can be reached at nandhini.arumugam@hp.com.

Jeyarani Venkatasamy holds a Masters degree in Computer Applications from Sri Sarada College for Women, Tirunelveli. She has been working as a senior sofware engineer in the Telecom and Mobile Solutions Lab, Hewlett-Packard, Bangalore for more than one year. The domain of her experience includes Web Services, Java, and J2EE-related technologies. She can be reached at jeyarani.venkatasamy@hp.com.

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