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Question about design of WS clients and their handlers

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posted 16 years ago

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Hello,

I have a WS client (i.e. a servlet) and a corresponding message handler. I simply want to retrieve IN the client a variable FROM the handler. Please let me know how to do that.

Here is a snippet from the handler:

What I want to achieve specifically is retrieving in my servlet an attachment that is available in my handler.

Any help immensely welcome.

Julien.

Jesus Angeles

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posted 16 years ago

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Which one do you need to access in your client, the attachment or one of MessageContext properties?

If you need the attachment, then it should be available in the response variable in your client; the same way you extracted it in the sample code you posted.

If what you need is an object in the handler, or a property in its MessageContext, I also am not aware how. But one way ( a dirty way ), is to chunk them in, into the mime soap. You may need to update other items like the wsdl, for this new info in the message.
[ May 27, 2006: Message edited by: Jesus Angeles ]

Jesus Angeles

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posted 16 years ago

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Also, usually, only the headers are touched in the handlers. It is not an adviseable design to touch other than the headers in the handlers; but yes, you have full access to the whole message. So there is nothing stopping you from doing so.
[ May 27, 2006: Message edited by: Jesus Angeles ]

Julien Martin

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posted 16 years ago

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Hello Jesus and thanks a lot for replying,

However I had a look at the response class and was not able to find anything that would allow me to get my attachement.

Here is the client (a servlet). The method is just a dummy method and does not do anything. What is more it is ill-named.

package pack;
 
import com.sun.xml.messaging.saaj.soap.ver1_1.SOAPMessageFactory1_1Impl;
import java.io.*;
import java.net.*;
import java.util.Enumeration;
import java.util.StringTokenizer;
 
import javax.servlet.*;
import javax.servlet.http.*;
import javax.xml.rpc.ServiceException;
import javax.xml.rpc.Stub;
import javax.xml.rpc.server.ServiceLifecycle;
import javax.xml.soap.MessageFactory;
import javax.xml.soap.MimeHeaders;
import javax.xml.soap.SOAPException;
import javax.xml.soap.SOAPMessage;
 
/**
 *
 * @author julien
 * @version
 */
public class ServletFetchesAttachment extends HttpServlet {
    
    
    
    /** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
                
        
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try { // This code block invokes the retrieveAttachment operation on web service
            getProvidesAttachmentSEIPort().retrieveAttachment();
        } catch(java.rmi.RemoteException ex) {
            ex.printStackTrace();
        } catch(Exception ex) {
            ex.printStackTrace();
        }
        
                
                
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Servlet ServletRetrieveAttachment</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>Servlet ServletRetrieveAttachment at " + request.getContextPath() + "</h1>");
        out.println("</body>");
        out.println("</html>");
        
        out.close();
    }
    
    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Returns a short description of the servlet.
     */
    public String getServletInfo() {
        return "Short description";
    }
    // </editor-fold>
    
    private pack.ProvidesAttachment getProvidesAttachment() {
        pack.ProvidesAttachment providesAttachment = null;
        try {
            javax.naming.InitialContext ic = new javax.naming.InitialContext();
            providesAttachment = (pack.ProvidesAttachment) ic.lookup("java:comp/env/service/ProvidesAttachment");
        } catch(javax.naming.NamingException ex) {
            ex.printStackTrace();
        }
        return providesAttachment;
    }
    
    private pack.ProvidesAttachmentSEI getProvidesAttachmentSEIPort() {
        pack.ProvidesAttachmentSEI providesAttachmentSEIPort = null;
        try {
            providesAttachmentSEIPort = getProvidesAttachment().getProvidesAttachmentSEIPort();
        } catch(javax.xml.rpc.ServiceException ex) {
            ex.printStackTrace();
            
        }
        return providesAttachmentSEIPort;
    }
    
    
}

Here is the client-side handler:

package pack;

/**
 * This is the implementation for the FetchesMessageHandlerSOAP Message Handler.
 * Created May 23, 2006 4:05:58 PM
 * @author julien
 */
//<editor-fold defaultstate="collapsed" desc="import statements. Click the + sign on the left to edit the code.">
import java.io.OutputStream;
import java.util.Iterator;
import javax.activation.DataHandler;
import javax.xml.rpc.handler.MessageContext;
import javax.xml.rpc.handler.HandlerInfo;
import javax.xml.rpc.handler.soap.SOAPMessageContext;
import javax.xml.namespace.QName;
import javax.xml.soap.AttachmentPart;
import javax.xml.soap.SOAPElement;
import javax.xml.soap.SOAPMessage;
import javax.xml.soap.SOAPPart;
import javax.xml.soap.SOAPEnvelope;
import javax.xml.soap.SOAPHeader;
import javax.xml.soap.SOAPBody;
import java.util.Date;
//</editor-fold>
public class FetchesMessageHandler extends javax.xml.rpc.handler.GenericHandler {
    // TODO Change and enhance the handle methods to suit individual needs.
    
    private QName[] headers;
    
    public void init(HandlerInfo config) {
        headers = config.getHeaders();
    }
    
    public javax.xml.namespace.QName[] getHeaders() {
        return headers;
    }
    
    // Currently prints out the contents of the SOAP body plus some date information.
    public boolean handleRequest(MessageContext context) {
        return true;
    }
    
    public boolean handleResponse(MessageContext context) {
        try{
            SOAPMessageContext smc = (SOAPMessageContext) context;
            
            SOAPMessage msg = smc.getMessage();
            
            msg.setProperty("prop", "tutu");
            
            
            Iterator it = msg.getAttachments();
            
            while(it.hasNext()){
                AttachmentPart ap = (AttachmentPart) it.next();
                DataHandler dh = ap.getDataHandler();
                OutputStream os = dh.getOutputStream();
                
                smc.setProperty("prop", os);
            }
        } catch(Exception e){
            e.printStackTrace();
        }
        
        return true;
    }
    
    public boolean handleFault(MessageContext context) {
        return true;
    }
    
    public void destroy() {
    }
    
}

Here is the endpoint:

Here is the endpoint-side handler:

package pack;

/**
 * This is the implementation for the AttachmentMessageHandlerSOAP Message Handler.
 * Created May 23, 2006 3:41:32 PM
 * @author julien
 */
//<editor-fold defaultstate="collapsed" desc="import statements. Click the + sign on the left to edit the code.">
import java.net.URL;
import javax.activation.DataHandler;
import javax.xml.rpc.handler.MessageContext;
import javax.xml.rpc.handler.HandlerInfo;
import javax.xml.rpc.handler.soap.SOAPMessageContext;
import javax.xml.namespace.QName;
import javax.xml.soap.AttachmentPart;
import javax.xml.soap.SOAPElement;
import javax.xml.soap.SOAPMessage;
import javax.xml.soap.SOAPPart;
import javax.xml.soap.SOAPEnvelope;
import javax.xml.soap.SOAPHeader;
import javax.xml.soap.SOAPBody;
import java.util.Date;
//</editor-fold>
public class AttachmentMessageHandler extends javax.xml.rpc.handler.GenericHandler {
    // TODO Change and enhance the handle methods to suit individual needs.
    
    private QName[] headers;
    
    public void init(HandlerInfo config) {
        headers = config.getHeaders();
    }
    
    public javax.xml.namespace.QName[] getHeaders() {
        return headers;
    }
    
    // Currently prints out the contents of the SOAP body plus some date information.
    public boolean handleRequest(MessageContext context) {
        
        return true;
    }
    
    public boolean handleResponse(MessageContext context) {
        
        try{
            SOAPMessageContext smc = (SOAPMessageContext) context;
            SOAPMessage msg = smc.getMessage();
            
            URL url = new URL ("file:///home//julien//tests//logo.gif");
            DataHandler dataHandler = new DataHandler(url);
            AttachmentPart apart = msg.createAttachmentPart(dataHandler);
            apart.setContentId("logo_id");
            msg.addAttachmentPart(apart);
 
          
        } catch(Exception e){
            e.printStackTrace();
        }
        return true;
    }
    
    public boolean handleFault(MessageContext context) {
        return true;
    }
    
    public void destroy() {
    }
    
  
}

Do you see my point??

Julien.

Jesus Angeles

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posted 16 years ago

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I see. You are passing the attachment from server handler to client handler. ...sort of, a trojan horse...hiding inside the message...not defined in the wsdl

The service can easily get its server handler/s MessageContext; however, I havent seen any connection between the client and the client handler/s MessageContext.

You might need to find a way, like write the attachment first to a file, and the servlet(client) will read that file.

Julien Martin

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posted 16 years ago

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Yes you're right. That's what I suspected: what I want to achieve is impossible. I am a beginner in WS and I just assumed that attachements had to be dealt with through handlers: erroneous assumption.
Thanks a lot for replying.
I am going to do some redesign.
Julien.

Julien Martin

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posted 16 years ago

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Hello,
Has anyone got any idea on how to redesign/refactor the above application in order for a j2ee client to fetch binary data from an endpoint?
Julien.

wise owen

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posted 16 years ago

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Why not try to use ThreadLocal for the client and client's handler. In the client's handler, it generates one object includes you the attachment and set to ThreadLocal. When the client code get response and uses the same ThreadLocal object to retrieve the stored attachment things you saved in client's handler.

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