package er.ajax;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.log4j.Logger;
import com.webobjects.appserver.WORequest;
import com.webobjects.appserver.WORequestHandler;
import com.webobjects.appserver.WOResponse;
import com.webobjects.appserver.WOSession;
import com.webobjects.foundation.NSData;
import com.webobjects.foundation.NSNotification;
import com.webobjects.foundation.NSNotificationCenter;
import er.extensions.appserver.ERXKeepAliveResponse;
import er.extensions.foundation.ERXSelectorUtilities;
/**
* Request handler that offers push-style notifications. <br>
* Gets registered under "/push/" on framework load.<br>
* You should open an Ajax.Request, implement onInteractive: and the do
* something useful when you get new data. Changes should be pushed with
* push(sessionID, someString);
* <p>
* TODO:
* <li>currently the request stays open even when the client closed it (which is bad)
* <li>implement a boundary scheme to tell when a "message" is complete. This
* means we need a special Ajax.Request that does it.
* <li>implement various client-side stuff to be actually useful (chats, EO
* notifications).
* <li>ask Frank about his EO layer
* <li>use the request handler path as a "topic", so we can have more than one on a page.
*
* @author ak
*/
public class AjaxPushRequestHandler extends WORequestHandler {
public static final String AjaxCometRequestHandlerKey = "push";
protected static Logger log = Logger.getLogger(AjaxPushRequestHandler.class);
private static ConcurrentHashMap<String, ConcurrentHashMap<String, ERXKeepAliveResponse>> responses = new ConcurrentHashMap<String, ConcurrentHashMap<String, ERXKeepAliveResponse>>();
public AjaxPushRequestHandler() {
NSNotificationCenter.defaultCenter().addObserver(this, ERXSelectorUtilities.notificationSelector("sessionDidTimeOut"), WOSession.SessionDidTimeOutNotification, null);
}
/**
* Remove stale responses when a session times out.
*
* @param n the session timeout notification
*/
public void sessionDidTimeOut(NSNotification n) {
String id = (String) n.object();
ConcurrentHashMap<String, ERXKeepAliveResponse> sessionResponses = responses.get(id);
if (sessionResponses != null) {
for (ERXKeepAliveResponse response : sessionResponses.values()) {
response.reset();
}
responses.remove(id);
}
}
/**
* Get/Create the current request for the session and return it.
*
* @param request the request
*/
@Override
public WOResponse handleRequest(WORequest request) {
String sessionID = request.sessionID();
String name = request.requestHandlerPath();
ERXKeepAliveResponse response = responseForSessionIDNamed(sessionID, name);
response.reset();
return response;
}
/**
* Return or create the correct response for the session ID.
*
* @param sessionID the session id of the response
* @param name the name of the response
* @return response for ID
*/
private static ERXKeepAliveResponse responseForSessionIDNamed(String sessionID, String name) {
ERXKeepAliveResponse response = null;
if (sessionID != null) {
if(name == null) {
name = "";
}
ConcurrentHashMap<String, ERXKeepAliveResponse> sessionResponses = responses.get(sessionID);
if (sessionResponses == null) {
ConcurrentHashMap<String, ERXKeepAliveResponse> newSessionResponses = new ConcurrentHashMap<String, ERXKeepAliveResponse>();
ConcurrentHashMap<String, ERXKeepAliveResponse> prevSessionResponses = responses.putIfAbsent(sessionID, newSessionResponses);
sessionResponses = (prevSessionResponses == null) ? newSessionResponses : prevSessionResponses;
}
response = sessionResponses.get(name);
if (response == null) {
ERXKeepAliveResponse newResponse = new ERXKeepAliveResponse();
ERXKeepAliveResponse prevResponse = sessionResponses.putIfAbsent(name, newResponse);
response = (prevResponse == null) ? newResponse : prevResponse;
}
}
return response;
}
/**
* Returns whether or not there is a response open for the given session id and name.
*
* @param sessionID the session id of the push response
* @param name the name of the push response
* @return whether or not there is still a response open
*/
public static boolean isResponseOpen(String sessionID, String name) {
ERXKeepAliveResponse response = responseForSessionIDNamed(sessionID, name);
return response != null;
}
/**
* Push a string message to the client. At the moment, there is no boundary
* handling, so be aware that you could get only half of a message.
*
* @param sessionID the session id of the push response
* @param name the name of the push response
*/
public static void stop(String sessionID, String name) {
Map<String, ERXKeepAliveResponse> sessionResponses = responses.get(sessionID);
if (sessionResponses != null) {
ERXKeepAliveResponse response = sessionResponses.get(name);
if (response != null) {
response.reset();
sessionResponses.remove(name);
}
// not going to do an empty check on sessionResponses, because we'd have to synchronize on
// the top-level responses to do it safely
}
}
/**
* Push a string message to the client. At the moment, there is no boundary
* handling, so be aware that you could get only half of a message.
*
* @param sessionID the session id of the push response
* @param name the name of the push response
* @param message the message to push
*/
public static void push(String sessionID, String name, String message) {
ERXKeepAliveResponse response = responseForSessionIDNamed(sessionID, name);
if (response != null) {
StringBuilder sb = new StringBuilder();
sb.append(message.length());
sb.append(':');
response.push(sb.toString());
response.push(message);
}
}
/**
* Push a data message to the client. At the moment, there is no boundary
* handling, so be aware that you could get only half of a message.
*
* @param sessionID the session id of the push response
* @param name the name of the push response
* @param message the message to push
*/
public static void push(String sessionID, String name, NSData message) {
ERXKeepAliveResponse response = responseForSessionIDNamed(sessionID, name);
if (response != null) {
StringBuilder sb = new StringBuilder();
sb.append(message.length());
sb.append(':');
response.push(sb.toString());
response.push(message.bytes());
}
}
}