org.springframework.web.socket.WebSocketHandler.java Source code

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Here is the source code for org.springframework.web.socket.WebSocketHandler.java

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/*
 * Copyright 2002-2013 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.web.socket;

/**
 * A handler for WebSocket messages and lifecycle events.
 *
 * <p>Implementations of this interface are encouraged to handle exceptions locally where
 * it makes sense or alternatively let the exception bubble up in which case by default
 * the exception is logged and the session closed with
 * {@link CloseStatus#SERVER_ERROR SERVER_ERROR(1011)}. The exception handling
 * strategy is provided by
 * {@link org.springframework.web.socket.handler.ExceptionWebSocketHandlerDecorator
 * ExceptionWebSocketHandlerDecorator} and it can be customized or replaced by decorating
 * the {@link WebSocketHandler} with a different decorator.
 *
 * @author Rossen Stoyanchev
 * @author Phillip Webb
 * @since 4.0
 */
public interface WebSocketHandler {

    /**
     * Invoked after WebSocket negotiation has succeeded and the WebSocket connection is
     * opened and ready for use.
     * @throws Exception this method can handle or propagate exceptions; see class-level
     * Javadoc for details.
     */
    void afterConnectionEstablished(WebSocketSession session) throws Exception;

    /**
     * Invoked when a new WebSocket message arrives.
     * @throws Exception this method can handle or propagate exceptions; see class-level
     * Javadoc for details.
     */
    void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception;

    /**
     * Handle an error from the underlying WebSocket message transport.
     * @throws Exception this method can handle or propagate exceptions; see class-level
     * Javadoc for details.
     */
    void handleTransportError(WebSocketSession session, Throwable exception) throws Exception;

    /**
     * Invoked after the WebSocket connection has been closed by either side, or after a
     * transport error has occurred. Although the session may technically still be open,
     * depending on the underlying implementation, sending messages at this point is
     * discouraged and most likely will not succeed.
     * @throws Exception this method can handle or propagate exceptions; see class-level
     * Javadoc for details.
     */
    void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception;

    /**
     * Whether the WebSocketHandler handles partial messages. If this flag is set to
     * {@code true} and the underlying WebSocket server supports partial messages,
     * then a large WebSocket message, or one of an unknown size may be split and
     * maybe received over multiple calls to
     * {@link #handleMessage(WebSocketSession, WebSocketMessage)}. The flag
     * {@link org.springframework.web.socket.WebSocketMessage#isLast()} indicates if
     * the message is partial and whether it is the last part.
     */
    boolean supportsPartialMessages();

}