/* * 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.client.communication; import com.google.gwt.user.client.Command; import com.vaadin.client.ApplicationConnection; import com.vaadin.shared.ui.ui.UIState.PushConfigurationState; import elemental.json.JsonObject; /** * Represents the client-side endpoint of a bidirectional ("push") communication * channel. Can be used to send UIDL request messages to the server and to * receive UIDL messages from the server (either asynchronously or as a response * to a UIDL request.) Delegates the UIDL handling to the * {@link ApplicationConnection}. * * @author Vaadin Ltd * @since 7.1 */ public interface PushConnection { /** * Two-phase construction to allow using GWT.create(). * * @param connection * The ApplicationConnection */ public void init(ApplicationConnection connection, PushConfigurationState pushConfigurationState); /** * Pushes a message to the server. Will throw an exception if the connection * is not active (see {@link #isActive()}). *
* Implementation detail: If the push connection is not connected and the * message can thus not be sent, the implementation must call * {@link CommunicationProblemHandler#pushNotConnected(JsonObject)}, which * will retry the send later. *
* This method must not be called if the push connection is not
* bidirectional (if {@link #isBidirectional()} returns false)
*
* @param payload
* the payload to push
* @throws IllegalStateException
* if this connection is not active
*
* @see #isActive()
*/
public void push(JsonObject payload);
/**
* Checks whether this push connection is in a state where it can push
* messages to the server. A connection is active until
* {@link #disconnect(Command)} has been called.
*
* @return true
if this connection can accept new messages;
* false
if this connection is disconnected or
* disconnecting.
*/
public boolean isActive();
/**
* Closes the push connection. To ensure correct message delivery order, new
* messages should not be sent using any other channel until it has been
* confirmed that all messages pending for this connection have been
* delivered. The provided command callback is invoked when messages can be
* passed using some other communication channel.
*
* After this method has been called, {@link #isActive()} returns
* false
. Calling this method for a connection that is no
* longer active will throw an exception.
*
* @param command
* callback command invoked when the connection has been properly
* disconnected
* @throws IllegalStateException
* if this connection is not active
*/
public void disconnect(Command command);
/**
* Returns a human readable string representation of the transport type used
* to communicate with the server.
*
* @since 7.1
* @return A human readable string representation of the transport type
*/
public String getTransportType();
/**
* Checks whether this push connection should be used for communication in
* both directions or if a normal XHR should be used for client to server
* communication.
*
* A bidirectional push connection must be able to reliably tell when it is
* connected and when it is not.
*
* @since 7.6
* @return true if the push connection should be used for messages in both
* directions, false if it should only be used for server to client
* messages
*/
public boolean isBidirectional();
}