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package cometedgwt.auction.client;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import com.google.gwt.core.client.GWT;
import com.google.gwt.json.client.JSONException;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONValue;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.rpc.ServiceDefTarget;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextArea;
/**
* This class contains all the internals used by a GWT to interact with the streaming server.
*
* Use it
*
* @author masini
*
*/
public class StreamingServiceGWTClientImpl implements StreamingService {
private int watchDogTimerTime = 100000;
Map callbacks = new HashMap();
private boolean keepAlive = false;
private final String streamingServicePath = GWT.getModuleBaseURL() + "streamingServlet";
private static StreamingService instance = null;
private final StreamingServiceInternalGWTAsync service = (StreamingServiceInternalGWTAsync) GWT.create(StreamingServiceInternalGWT.class);
private final Map waitingSubscriber = new HashMap();
private final static AsyncCallback voidCallback = new AsyncCallback() {
public void onFailure(Throwable caught) {
}
public void onSuccess(Object result) {
}
};
private final AsyncCallback restartStreamingCallback = new AsyncCallback() {
public void onFailure(Throwable caught) {
}
public void onSuccess(Object result) {
restartStreamingFromIFrame();
callback("restartStreaming", (String) result);
}
};
/**
* Receive hearthbeats from the streaming server. It sets keepAlive flag to true to prevent the Timer
* to restart the streaming and then call the client callback (maybe the client has to do something
* with the heartbeat itself).
*/
private final AsyncCallback internalKeepAliveCallback = new AsyncCallback() {
public void onFailure(Throwable caught) {
}
public void onSuccess(Object result) {
alert("keepAlive");
keepAlive = true;
watchDogTimerTime = 10 * Integer.parseInt(result.toString());
for (Iterator iter = waitingSubscriber.entrySet().iterator(); iter.hasNext();) {
Entry callback = (Entry) iter.next();
/*
Take care, the Map implementation can be different from his Java counterpart.
I think it uses object identity instead of object equality, so for instance two equals
String done in different way can lend to two different keys in the map.
Try this
void testMap(Object key, Object value)
{
Map test = new HashMap();
test.put(key.toString(),value);
if(!test.containsKey("testKey"))
{
GWT.log("bug in map found !!!",null);
}
}
If called this way:
testMap("testKey", new Object());
that code will print the warning row !!!!!
Should be fixed.
*/
subScribeToEvent((String) callback.getKey(), (AsyncCallback) callback.getValue());
iter.remove();
}
callback("keepAlive", "");
}
};
/*
* Sharing StreamingService instance can be a problem with two Hosted browser that share the same GWT Shell,
* but not with real browser.
*/
public static StreamingService getInstance() {
if (instance == null) {
instance = new StreamingServiceGWTClientImpl();
}
return instance;
}
private StreamingServiceGWTClientImpl() {
callbacks.put("keepAliveInternal", internalKeepAliveCallback);
callbacks.put("restartStreamingInternal", restartStreamingCallback);
((ServiceDefTarget) service).setServiceEntryPoint(GWT.getModuleBaseURL() + "streamingService");
setUpNativeCode(this);
restartStreamingFromIFrame();
createWatchDogTimer();
}
/**
* If we have a callback for the "event" (and we should if we subscribed) then let's call it.
*
* @param event: contains the event we subscribed
* @param data: datas that come from the server
*/
private void callback(String topicName, String data) {
keepAlive = true;
alert("received callback for (" + topicName + "," + data + ")");
if (callbacks.containsKey(topicName)) {
AsyncCallback callback = (AsyncCallback) callbacks.get(topicName);
try {
Object dataToSend = data;
if (data.startsWith("$JSONSTART$") && data.endsWith("$JSONEND$")) {
dataToSend = JSONParser.parse(data.substring("$JSONSTART$".length(), data.length() - "$JSONEND$".length()));
}
callback.onSuccess(dataToSend);
} catch (JSONException e) {
callback.onFailure(e);
}
} else {
alert("received event for a not subscribed topic: '" + topicName + "'");
alert("current topics are: " + callbacks.keySet());
}
}
/**
* Setup the two Javascript method used for the callback from the server
*
* @param thisInstance: a trick, because I was unable to use this !!!
*/
private native void setUpNativeCode(StreamingService thisInstance) /*-{
$wnd.callback = function(topicName, data)
{
thisInstance.@cometedgwt.auction.client.StreamingServiceGWTClientImpl::callback(Ljava/lang/String;Ljava/lang/String;)(topicName,data);
}
}-*/;
//thisInstance.@org.gwtcomet.client.StreamingServiceGWTClientImpl::callback(Ljava/lang/String;Ljava/lang/String;)(topicName,data);
/**
* A Timer that every 20s check
* if everything is working.
*
*/
private void createWatchDogTimer() {
Timer t = new Timer() {
public void run() {
if (!keepAlive) {
alert("the dog is angry !!! Awake streaming !!!");
restartStreamingFromIFrame();
}
keepAlive = false;
}
};
t.scheduleRepeating(watchDogTimerTime);
}
/**
* Uses DOM to create, if necessary, the iframe, then sets the src attribute to start
* the streaming. It's important to clear the "old" iframe when restarting, or spurios
* Javascript can send old event to the callback method
*/
private void restartStreamingFromIFrame() {
Element iframe = DOM.getElementById("__gwt_streamingFrame");
if (iframe != null) {
DOM.removeChild(RootPanel.getBodyElement(), iframe);
}
iframe = DOM.createIFrame();
DOM.setAttribute(iframe, "id", "__gwt_streamingFrame");
DOM.setStyleAttribute(iframe, "width", "0");
DOM.setStyleAttribute(iframe, "height", "0");
DOM.setStyleAttribute(iframe, "border", "0");
DOM.appendChild(RootPanel.getBodyElement(), iframe);
DOM.setAttribute(iframe, "src", streamingServicePath);
}
/* (non-Javadoc)
* @see org.gwtcomet.client.StreamingService#sendMessage(java.lang.String, java.lang.String)
*/
public void sendMessage(String topicName, String data) {
service.sendMessage(topicName, data, voidCallback);
}
/* (non-Javadoc)
* @see org.gwtcomet.client.StreamingService#sendMessage(java.lang.String, com.google.gwt.sample.json.client.JSONValue)
*/
public void sendMessage(String topicName, JSONValue object) {
sendMessage(topicName, "$JSONSTART$" + object.toString() + "$JSONEND$");
}
/* (non-Javadoc)
* @see org.gwtcomet.client.StreamingService#subScribeToEvent(java.lang.String, com.google.gwt.user.client.rpc.AsyncCallback)
*/
public void subScribeToEvent(String topicName, AsyncCallback callback) {
if (keepAlive) {
alert("Streaming is alive, subscribing to '" + topicName + "' with callback " + callback);
service.subscribeToTopic(topicName, voidCallback);
callbacks.put(topicName, callback);
alert(callbacks.toString());
} else {
alert("Streaming is not alive, subscriber '" + topicName + "' is cached with callback " + callback + " until online");
waitingSubscriber.put(topicName, callback);
}
}
private final TextArea textArea = new TextArea();
private void alert(String message) {
if (GWT.isScript()) {
RootPanel debugDiv = RootPanel.get("debug");
if (debugDiv != null) {
// if(debugDiv.getWidgetIndex(textArea)==-1)
// {
// textArea.setVisibleLines(30);
// textArea.setWidth("100%");
// textArea.setText("");
// debugDiv.add(textArea);
// }
//
// textArea.setText(textArea.getText()+"\n"+new Date()+"("+System.currentTimeMillis()+"):"+message);
}
} else {
GWT.log(message, null);
}
}
}