/** A SIP Servlet to handle SIP REGISTER requests. */
public class RegistrarServlet extends SipServlet {

    // inject the SipFactory
    @Resource(mappedName="sip/ClickToDial")
    private SipFactory sf;
    
    /** Handle a SIP Register request. */
    protected void doRegister(SipServletRequest req) 
        throws ServletException, IOException 
    {
        int response;

        // Figure out the name the user is registering with.  This is the
        // user portion of the SIP URI, e.g. "Bob" in "sip:Bob@x.y.z:port"
        String username = ...
        
        // get the Person object from the database
        Person p = mf.getPerson(username);
        if (p == null) {
            // no person found in the database
            response = SipServletResponse.SC_NOT_FOUND;
        } else {
            // the Expires header tells us if this is a registration or
            // unregistration attempt.
            int expires = Integer.parseInt(req.getHeader("Expires"));

            if (expires == 0) {
                // unregister
                response = handleUnregister(req, p);
            } else {
                // register
                response = handleRegister(req, p);
            }
        }

        // send the response
        SipServletResponse resp = req.createResponse(response);
        resp.send();
    }
    
    /** Handle a registration request */
    private int handleRegister(SipServletRequest req, Person p)
        throws ServletException
    {

        // Get the contact address from the request.  Prefer the
        // "Contact" address if given, otherwise use the "To" address
        Address addr = sf.createAddress(req.getHeader("Contact"));

        // store the contact address in the database
        p.setTelephone(addr.getURI().toString());
        
        ModelFacade mf = (ModelFacade) getServletContext().getAttribute("Model");
        mf.updatePerson(p);
        
        return SipServletResponse.SC_OK;
    }    
}

/** Place a phone call when a user clicks */
public class PlaceCallServlet extends HttpServlet {
    
    // inject the SipFactory
    @Resource(mappedName="sip/ClickToDial")
    private SipFactory sf;
    
    /** Processes requests for HTTP POST method. */
    protected void processRequest(HttpServletRequest request, 
                                  HttpServletResponse response)
        throws ServletException, IOException 
    {
        // get the source and target from the request
        String sourceUserName = request.getParameter("source");
        String targetUserName = request.getParameter("target");
        
        // look up the relevant Person objects in the database
        ModelFacade mf = (ModelFacade) getServletContext().getAttribute("Model");
        Person source = mf.getPerson(sourceUserName);
        Person target = mf.getPerson(targetUserName);

        // get the phone numbers as SIP Addresses
        SipApplicationSession appSession = sf.createApplicationSession();
        Address to = sf.createAddress(source.getTelephone());
        Address from = sf.createAddress(target.getTelephone());
        
        // create an INVITE request to the first party from the second
        SipServletRequest req = sf.createRequest(appSession, "INVITE", from, to);
        
        // store the second party's address in the sip session
        req.getSession().setAttribute("SecondPartyAddress", from);
        
        // send the INVITE request            
        req.send();
    }   
}

/** A SIP Serlvet that handles responses to click-to-dial invites
 */
public class CallSipServlet extends SipServlet implements SipSessionListener {

    // inject the SipFactory
    @Resource(mappedName="sip/ClickToDial")
    private SipFactory sf;
    
    
    /** Handle an OK response. */  
    protected void doSuccessResponse(SipServletResponse resp)
        throws ServletException, IOException 
    {
        SipSession session = resp.getSession();
                
        // if the response was OK, invite the other party
        if (resp.getStatus() == SipServletResponse.SC_OK) {
            
            // we are in one of two states here.  Either this OK is from
            // the original invitee, meaning they answered and it is time
            // to ring the second pa
2000
rty, or the OK is from the second
            // party, and we should acknowlege the call with both sides
            
            
            // check for the first case, where this OK is from the original
            // invitee
            Address secondPartyAddress = 
                    (Address) resp.getSession().getAttribute("SecondPartyAddress");  
            if (secondPartyAddress != null) {
                

                // invite the second party
                SipServletRequest invite = sf.createRequest(resp.getApplicationSession(),
                        "INVITE", session.getRemoteParty(), secondPartyAddress);
                
                // get the SDP from the OK message
                if (resp.getContentType().equals("application/sdp")) {
                    invite.setContent(resp.getContent(), "application/sdp");
                }        
                
                // send the invite
                invite.send();
            } else {
                // send acks
                SipServletRequest secondPartyAck = resp.createAck();
                SipServletRequest firstPartyAck = 
                        (SipServletRequest) resp.getSession().getAttribute("FirstPartyAck");
            
                // get the SDP from the second party's OK message
                if (resp.getContentType().equals("application/sdp")) {
                    firstPartyAck.setContent(resp.getContent(), "application/sdp");
                }
                
                firstPartyAck.send();
                secondPartyAck.send();
            }
        }
    }
}

Received register request: "Bob"<sip:Bob@192.168.2.103>
Register address: "Bob"<sip:Bob@192.168.2.103:9990;transport=udp>;expires=3600