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package org.gwtcomet.server;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import org.atmosphere.cpr.AtmosphereResource;
import org.atmosphere.cpr.AtmosphereServlet;
import org.atmosphere.cpr.BroadcastFilter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
public class StreamingServlet extends RemoteServiceServlet {
private static final Logger logger = LoggerFactory.getLogger(StreamingServlet.class);
private final static byte[] JUNK = ("<!-- Comet is a programming technique that enables web " +
"servers to send data to the client without having any need " +
"for the client to request it. -->\n").getBytes();
private int counter = 0;
public StreamingServlet() {
}
private void writeToStream(OutputStream out, String contents) throws IOException {
out.write(contents.getBytes());
out.flush();
}
private void sendKeepAlive(OutputStream out) throws IOException {
writeToStream(out, writeCallback(new StringBuffer(), "keepAliveInternal",
Integer.toString(counter++)).toString());
}
private StringBuffer writeCallback(StringBuffer stream,
String topicName, String data) throws UnsupportedEncodingException {
stream.append(" <script type='text/javascript'>\n");
stream.append("\twindow.parent.callback('" + topicName +
"',unescape('" + URLEncoder.encode(data, "iso-8859-1")
.replaceAll("\\x2B", "%20") + "'));\n");
stream.append("</script>\n");
return stream;
}
@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=ISO-8859-1");
AtmosphereResource e =
(AtmosphereResource) request.getAttribute(AtmosphereServlet.ATMOSPHERE_RESOURCE);
if (!e.getBroadcaster().getID().equals("GWT")){
synchronized(e.getBroadcaster()){
e.getBroadcaster().setID("GWT");
e.getBroadcaster().getBroadcasterConfig().addFilter(new GWTBroadcasterFilter());
}
}
sendKeepAlive(response.getOutputStream());
e.suspend();
}
private static final class GWTBroadcasterFilter implements BroadcastFilter {
public BroadcastAction filter(Object originalMsg, Object message) {
try {
StreamingServiceBusiness.Event event = (StreamingServiceBusiness.Event) message;
StringBuffer stream = new StringBuffer();
stream.append("<script type='text/javascript'>\n");
stream.append("\twindow.parent.callback('" + event.queueName +
"',unescape('" + URLEncoder.encode(event.message, "iso-8859-1")
.replaceAll("\\x2B", "%20") + "'));\n");
stream.append("</script>\n");
return new BroadcastAction(stream);
} catch (UnsupportedEncodingException ex) {
logger.error("failed to encode message", ex);
}
return new BroadcastAction(message);
}
}
}