Package org.atmosphere.gwt.server.impl

Source Code of org.atmosphere.gwt.server.impl.GwtResponseWriterImpl

/*
* Copyright 2011 Jeanfrancois Arcand
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package org.atmosphere.gwt.server.impl;

import com.google.gwt.rpc.server.ClientOracle;
import com.google.gwt.user.client.rpc.SerializationException;
import com.google.gwt.rpc.server.RPC;
import com.google.gwt.user.server.rpc.SerializationPolicy;
import com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter;
import org.atmosphere.gwt.server.GwtResponseWriter;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.NotSerializableException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ScheduledFuture;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.atmosphere.gwt.server.deflate.DeflaterOutputStream;
import java.util.Date;
import java.util.concurrent.atomic.AtomicInteger;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
*
* @author p.havelaar
*/
public abstract class GwtResponseWriterImpl implements GwtResponseWriter {


  protected Writer writer;
  protected final GwtAtmosphereResourceImpl resource;
    protected final int connectionID;
    protected final Logger logger = LoggerFactory.getLogger(getClass());


  protected GwtResponseWriterImpl(GwtAtmosphereResourceImpl resource, SerializationPolicy serializationPolicy, ClientOracle clientOracle) {
        this.resource = resource;
    this.serializationPolicy = serializationPolicy;
    this.clientOracle = clientOracle;
        this.connectionID = connectionIDs.getAndIncrement();
  }


    @Override
  public synchronized boolean isTerminated() {
    return terminated;
  }

  protected boolean isDeRPC() {
    return clientOracle != null;
  }

  public HttpServletRequest getRequest() {
    return resource.getAtmosphereResource().getRequest();
  }

  public HttpServletResponse getResponse() {
    return resource.getAtmosphereResource().getResponse();
  }

  synchronized void scheduleHeartbeat() {
        if (logger.isTraceEnabled()) {
            logger.trace("Schedule heartbeat for ["+connectionID+"]");
            logger.trace("Last write for ["+connectionID+"] was " + new Date(lastWriteTime).toString());
        }
    lastWriteTime = System.currentTimeMillis();
    if (heartbeatFuture != null) {
      heartbeatFuture.cancel(false);
    }
    heartbeatFuture = resource.scheduleHeartbeat();
  }

  @Override
  public void sendError(int statusCode) throws IOException {
    sendError(statusCode, null);
  }

  @Override
  public synchronized void sendError(int statusCode, String message) throws IOException {
    try {
            if (writer == null) {
                getResponse().reset();
                getResponse().setHeader("Cache-Control", "no-cache");
                getResponse().setCharacterEncoding("UTF-8");

                writer = new OutputStreamWriter(getResponse().getOutputStream(), "UTF-8");
            }

      doSendError(statusCode, message);
    }
    catch (IllegalStateException e) {
      logger.error("Error resetting response to send error: " + e.getMessage());
    }
        catch (IOException e) {
            logger.debug("Failed to send error to client", e);
        }
    finally {
      setTerminated(true);
    }
  }

    protected OutputStream getOutputStream(OutputStream outputStream) {
        return outputStream;
    }
   
  public synchronized void initiate() throws IOException {
    getResponse().setHeader("Cache-Control", "no-cache");
    getResponse().setCharacterEncoding("UTF-8");

    OutputStream outputStream = getResponse().getOutputStream();
        outputStream = getOutputStream(outputStream);

    String acceptEncoding = getRequest().getHeader("Accept-Encoding");
    if (acceptEncoding != null && acceptEncoding.contains("deflate")) {
      getResponse().setHeader("Content-Encoding", "deflate");
      outputStream = new DeflaterOutputStream(outputStream);
    }

    writer = new OutputStreamWriter(outputStream, "UTF-8");

        if (logger.isTraceEnabled()) {
            logger.trace("Initiated ["+connectionID+"]");
        }
        getRequest().setAttribute("connectionID", connectionID);
    scheduleHeartbeat();
  }

  public void suspend() throws IOException {
    try {
      synchronized (this) {
        if (terminated) {
          return;
        }
                if (logger.isTraceEnabled()) {
                    logger.trace("Suspending ["+connectionID+"]");
                }
        doSuspend();

        flush();
      }
    }
    catch (IOException e) {
      logger.error("Error suspending response", e);
      synchronized (this) {
        setTerminated(false);
      }
            throw e;
    }
  }

  @Override
  public synchronized void terminate() throws IOException {
    if (!terminated) {
      try {
        doTerminate();
        flush();
      }
      finally {
        setTerminated(true);
      }
    }
  }

  void tryTerminate() {
    try {
      terminate();
    }
    catch (IOException e) {
      logger.error("Error terminating response", e);
    }
  }

  @Override
  public void write(Serializable message) throws IOException {
    write(Collections.singletonList(message), true);
  }

  @Override
  public void write(Serializable message, boolean flush) throws IOException {
    write(Collections.singletonList(message), flush);
  }

  @Override
  public void write(List<? extends Serializable> messages) throws IOException {
    write(messages, true);
  }

  @Override
  public synchronized void write(List<? extends Serializable> messages, boolean flush) throws IOException {
    if (terminated) {
      throw new IOException("CometServletResponse terminated");
    }
    try {
            if (messages.size() == 1 && messages.get(0) instanceof Heartbeat) {
                heartbeat();
            } else {
                if (logger.isTraceEnabled()) {
                    logger.trace("Writing #" + messages.size() + " messages to ["+connectionID+"]");
                }
                doWrite(messages);
                if (flush) {
                    flush();
                }
                scheduleHeartbeat();
            }
    }
    catch (IOException e) {
            resource.resumeAfterDeath();
      setTerminated(false);
      throw e;
    }
  }

  @Override
  public synchronized void heartbeat() throws IOException {
    if (!terminated) {
      try {
                logger.trace("Sending heartbeat ["+connectionID+"]");
        doHeartbeat();
        flush();
        scheduleHeartbeat();
      }
      catch (IOException e) {
                logger.debug("Failed to send heartbeat", e);
        setTerminated(false);
        throw e;
      }
    }
  }

  synchronized void flush() throws IOException {
    writer.flush();
  }

  synchronized void setTerminated(boolean serverInitiated) {

        if (!terminated) {
            terminated = true;

            if (logger.isTraceEnabled()) {
                logger.trace("Terminating ["+connectionID+"]");
            }
            if (heartbeatFuture != null) {
                heartbeatFuture.cancel(false);
                heartbeatFuture = null;
            }

            if (serverInitiated) {
                try {
                    if (writer != null) {
                        writer.close();
                    }
                }
                catch (IOException e) {
                    logger.error("Error closing connection", e);
                }
                resource.terminate(serverInitiated);
            }
        }
  }

    @Override
    public long getLastWriteTime() {
        return lastWriteTime;
    }

    protected abstract void doSendError(int statusCode, String message) throws IOException;

  protected abstract void doSuspend() throws IOException;

  protected abstract void doWrite(List<? extends Serializable> messages) throws IOException;

  protected abstract void doHeartbeat() throws IOException;

  protected abstract void doTerminate() throws IOException;

    protected boolean hasSession() {
        HttpSession session = resource.getSession(false);
        return session != null;
    }

  protected String serialize(Serializable message) throws NotSerializableException, UnsupportedEncodingException {
    try {
      if (clientOracle == null) {
        ServerSerializationStreamWriter streamWriter = new ServerSerializationStreamWriter(serializationPolicy);
        streamWriter.prepareToWrite();
        streamWriter.writeObject(message);
        return streamWriter.toString();
      }
      else {
        ByteArrayOutputStream result = new ByteArrayOutputStream();
        RPC.streamResponseForSuccess(clientOracle, result, message);
        return new String(result.toByteArray(), "UTF-8");
      }
    }
    catch (SerializationException e) {
      throw new NotSerializableException("Unable to serialize object, message: " + e.getMessage());
    }
  }


  private final SerializationPolicy serializationPolicy;
  private final ClientOracle clientOracle;
  private boolean terminated;
  private volatile long lastWriteTime;
  private ScheduledFuture<?> heartbeatFuture;
    private static AtomicInteger connectionIDs = new AtomicInteger(1);
}
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