/*
* Copyright 2000-2014 Vaadin Ltd.
*
* 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 com.vaadin.server.communication;
import java.io.IOException;
import javax.servlet.http.HttpServletResponse;
import com.vaadin.server.ServletPortletHelper;
import com.vaadin.server.SessionExpiredHandler;
import com.vaadin.server.SynchronizedRequestHandler;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinResponse;
import com.vaadin.server.VaadinSession;
import com.vaadin.shared.ui.ui.UIConstants;
import com.vaadin.ui.UI;
/**
* Handles heartbeat requests. Heartbeat requests are periodically sent by the
* client-side to inform the server that the UI sending the heartbeat is still
* alive (the browser window is open, the connection is up) even when there are
* no UIDL requests for a prolonged period of time. UIs that do not receive
* either heartbeat or UIDL requests are eventually removed from the session and
* garbage collected.
*
* @author Vaadin Ltd
* @since 7.1
*/
public class HeartbeatHandler extends SynchronizedRequestHandler implements
SessionExpiredHandler {
@Override
protected boolean canHandleRequest(VaadinRequest request) {
return ServletPortletHelper.isHeartbeatRequest(request);
}
/**
* Handles a heartbeat request for the given session. Reads the GET
* parameter named {@link UIConstants#UI_ID_PARAMETER} to identify the UI.
* If the UI is found in the session, sets it
* {@link UI#getLastHeartbeatTimestamp() heartbeat timestamp} to the current
* time. Otherwise, writes a HTTP Not Found error to the response.
*/
@Override
public boolean synchronizedHandleRequest(VaadinSession session,
VaadinRequest request, VaadinResponse response) throws IOException {
UI ui = session.getService().findUI(request);
if (ui != null) {
ui.setLastHeartbeatTimestamp(System.currentTimeMillis());
// Ensure that the browser does not cache heartbeat responses.
// iOS 6 Safari requires this (#10370)
response.setHeader("Cache-Control", "no-cache");
// If Content-Type is not set, browsers assume text/html and may
// complain about the empty response body (#12182)
response.setHeader("Content-Type", "text/plain");
} else {
response.sendError(HttpServletResponse.SC_NOT_FOUND, "UI not found");
}
return true;
}
/*
* (non-Javadoc)
*
* @see
* com.vaadin.server.SessionExpiredHandler#handleSessionExpired(com.vaadin
* .server.VaadinRequest, com.vaadin.server.VaadinResponse)
*/
@Override
public boolean handleSessionExpired(VaadinRequest request,
VaadinResponse response) throws IOException {
if (!ServletPortletHelper.isHeartbeatRequest(request)) {
return false;
}
response.sendError(HttpServletResponse.SC_GONE, "Session expired");
return true;
}
}