Transport.java

/*
 * Transport.java February 2007
 *
 * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
 *
 * 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.simpleframework.transport;

import java.io.IOException;
import java.nio.ByteBuffer;

/**
 * The <code>Transport</code> interface represents a low level means to deliver
 * content to the connected client. Typically this will be a connected,
 * non-blocking, TCP connection. However, for tests and other purposes this may
 * be adapted. The general contract of the transport is that it provides
 * non-blocking reads and blocking writes. Blocking writes are required to
 * ensure that memory does not build up in output buffers during high load
 * periods.
 * 
 * @author Niall Gallagher
 */
public interface Transport extends Socket {

    /**
     * This is used to perform a non-blocking read on the transport. If there
     * are no bytes available on the input buffers then this method will return
     * zero and the buffer will remain the same. If there is data and the buffer
     * can be filled then this will return the number of bytes read. Finally if
     * the socket is closed this will return a -1 value.
     * 
     * @param buffer
     *            this is the buffer to append the bytes to
     * 
     * @return this returns the number of bytes that have been read
     */
    int read(ByteBuffer buffer) throws IOException;

    /**
     * This method is used to deliver the provided buffer of bytes to the
     * underlying transport. Depending on the connection type the array may be
     * encoded for SSL transport or send directly. Any implementation may choose
     * to buffer the bytes for performance.
     * 
     * @param buffer
     *            this is the buffer of bytes to send to the client
     */
    void write(ByteBuffer buffer) throws IOException;

    /**
     * This method is used to flush the contents of the buffer to the client.
     * This method will block not block but will simply flush any data to the
     * underlying transport. Internally the data will be queued for delivery to
     * the connected entity.
     */
    void flush() throws IOException;

    /**
     * This is used to close the transport and the underlying socket. If a close
     * is performed on the transport then no more bytes can be read from or
     * written to the transport and the client will receive a connection close
     * on their side.
     */
    void close() throws IOException;
}