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- /*
- * Copyright 2000-2018 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;
- }
-
- // Ensure that the browser does not cache expired response.
- // 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");
-
- response.sendError(HttpServletResponse.SC_NOT_FOUND, "Session expired");
- return true;
- }
- }
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