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wAsync: A WebSockets/HTTP Client Library
There is a newer version: 3.0.2
/*
 * Copyright 2015 Async-IO.org
 *
 * 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.wasync;

import java.io.IOException;

import java.util.concurrent.TimeUnit;

/**
 * A Socket represents a connection to a remote server. A Socket abstract the transport used and will negotiate
 * the best {@link org.atmosphere.wasync.Request.TRANSPORT} to communicate with the Server.
 * 
 * Depending on the transport used, one or two connections will be opened. For WebSocket, a single, bi-directional connection
 * will be used. For other transport like streaming, server side events and long-polling, a connection will be opened
 * to the server and will be suspended (stay opened) until an event happen on the server. A second connection will be opened every time the {@link #fire(Object)}
 * method is invoked and cached for further re-use.
 * 
 *
 * As simple as
 *      Client client = AtmosphereClientFactory.getDefault().newClient();

     RequestBuilder request = client.newRequestBuilder()
             .method(Request.METHOD.GET)
             .uri(targetUrl + "/suspend")
             .encoder(new Encoder<String, Reader>() {        // Stream the request body
                 @Override
                 public Reader encode(String s) {
                     return new StringReader(s);
                 }
             })
             .decoder(new Decoder<String, Reader>() {
                  @Override
                 public Reader decode(String s) {
                     return new StringReader(s);
                 }
             })
             .transport(Request.TRANSPORT.WEBSOCKET)                        // Try WebSocket
             .transport(Request.TRANSPORT.LONG_POLLING);                    // Fallback to Long-Polling

     Socket socket = client.create();
     socket.on("message", new Function<String>() {
         @Override
         public void on(Reader r) {
             // Read the response
         }
     }).on(new Function<IOException>() {

         @Override
         public void on(Throwable t) {
             // Some IOException occurred
         }

     }).open(request.build()).fire("echo");
 * 
 *
 * @author Jeanfrancois Arcand
 */
public interface Socket {

    /**
     * The current state of the underlying Socket.
     */
    public enum STATUS {
        /**
         * The socket is not yet connected
         */
        INIT,
        /**
         * The socket is open and ready to send messages
         */
        OPEN,
        /**
         * The socket was closed and re-opened
         */
        REOPENED,
        /**
         * The socket is close
         */
        CLOSE,
        /**
         * The socket is broken
         */
        ERROR }

    /**
     * Send data to the remote Server. The object will first be delivered to the set of {@link Encoder}, and then send to the server.
     * The server's response will be delivered to the set of defined {@link Function} using the opened {@link Transport}, e.g for
     * {@link Request.TRANSPORT#WEBSOCKET}, the same connection will be re-used and, for others transports, the suspended connection.
     * @param data object to send
     * @return a {@link Future}
     * @throws IOException
     */
    Future fire(Object data) throws IOException;

    /**
     * Associate a {@link Function} with the Socket. When a response is received, the library will try to associated
     * the decoded message (decoded by {@link Decoder}) to the defined type of the {@link Function}
     * @param function a {@link Function}
     * @return this
     */
    Socket on(Function function);

    /**
     * Associate a {@link Function} with the Socket. When a response is received, the library will try to associated
     * the decoded message (decoded by {@link Decoder}) to the defined type of the {@link Function}. The default messages
     * are defined by {@link org.atmosphere.wasync.Event} but handling of custom message can be done using a {@link FunctionResolver}
     * @param function a {@link Function}
     * @return this
     */
    Socket on(String functionMessage, Function function);

    /**
     * Associate a {@link Function} with an {@link Event}. When the event happen the library will try to associated
     * the decoded event (decoded by {@link Decoder}) to the defined type of the {@link Function}. The default event
     * are defined by {@link org.atmosphere.wasync.Event} but handling of custom event can be done using a {@link FunctionResolver}
     * @param function a {@link Function}
     * @return this
     */
    Socket on(Event event, Function function);

    /**
     * Connect to the remote Server using the {@link Request}'s information.
     * @param request a {@link Request}
     * @return this
     * @throws IOException in case the connect fails or a network failure occurs.
     */
    Socket open(Request request) throws IOException;
    
    /**
     * Connect to the remote Server using the {@link Request}'s information, will timeout if the connection failed to open 
     * within a certain time.
     * @param request a {@link Request}
     * @param timeout the maximum time to wait
     * @param unit the time unit of the timeout argument
     * @return this
     * @throws IOException in case the connect fails or a network failure occurs.
     */
    Socket open(Request request, long timeout, TimeUnit unit) throws IOException;

    /**
     * Close this Socket, asynchronously.
     */
    void close();

    /**
     *  Return the {@link STATUS} of this Socket.
     */
    STATUS status();
}