/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.net.daytime;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;

import org.apache.commons.net.DatagramSocketClient;

The DaytimeUDPClient class is a UDP implementation of a client for the Daytime protocol described in RFC 867. To use the class, merely open a local datagram socket with  open and call  getTime to retrieve the daytime string, then call  close to close the connection properly. Unlike DaytimeTCPClient, successive calls to  getTime are permitted without re-establishing a connection. That is because UDP is a connectionless protocol and the Daytime protocol is stateless. 
See Also:
DaytimeTCPClient/**
 * The DaytimeUDPClient class is a UDP implementation of a client for the
 * Daytime protocol described in RFC 867.  To use the class, merely
 * open a local datagram socket with
 * {@link org.apache.commons.net.DatagramSocketClient#open  open }
 * and call {@link #getTime  getTime } to retrieve the daytime
 * string, then
 * call {@link org.apache.commons.net.DatagramSocketClient#close  close }
 * to close the connection properly.  Unlike
 * {@link org.apache.commons.net.daytime.DaytimeTCPClient},
 * successive calls to {@link #getTime  getTime } are permitted
 * without re-establishing a connection.  That is because UDP is a
 * connectionless protocol and the Daytime protocol is stateless.
 * @see DaytimeTCPClient
 */
public final class DaytimeUDPClient extends DatagramSocketClient
{
    
The default daytime port.  It is set to 13 according to RFC 867. /** The default daytime port.  It is set to 13 according to RFC 867. */
    public static final int DEFAULT_PORT = 13;

    private final byte[] __dummyData = new byte[1];
    // Received dates should be less than 256 bytes
    private final byte[] __timeData = new byte[256];

    
Retrieves the time string from the specified server and port and
returns it.
Params:
host – The address of the server.
port – The port of the service.
Throws:
IOException – If an error occurs while retrieving the time.
Returns:
The time string./**
     * Retrieves the time string from the specified server and port and
     * returns it.
     *
     * @param host The address of the server.
     * @param port The port of the service.
     * @return The time string.
     * @throws IOException If an error occurs while retrieving the time.
     */
    public String getTime(InetAddress host, int port) throws IOException
    {
        DatagramPacket sendPacket, receivePacket;

        sendPacket =
            new DatagramPacket(__dummyData, __dummyData.length, host, port);
        receivePacket = new DatagramPacket(__timeData, __timeData.length);

        _socket_.send(sendPacket);
        _socket_.receive(receivePacket);

        return new String(receivePacket.getData(), 0, receivePacket.getLength(), getCharsetName()); // Java 1.6 can use getCharset()
    }

    
Same as getTime(host, DaytimeUDPClient.DEFAULT_PORT);
Params:
host – the host
Throws:
IOException – on error
Returns:
 the time/** Same as <code>getTime(host, DaytimeUDPClient.DEFAULT_PORT);</code>
     * @param host the host
     * @return  the time
     * @throws IOException on error
     */
    public String getTime(InetAddress host) throws IOException
    {
        return getTime(host, DEFAULT_PORT);
    }

}