https://developers.google.com/protocol-buffers/protobuf-java/: Core Protocol Buffers library. Protocol Buffers are a way of encoding structured data in an efficient yet extensible format. 
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package com.google.protobuf;

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


An output target for raw bytes. This interface provides semantics that support two types of
writing:

Traditional write operations: (as defined by OutputStream) where the target method is responsible for either copying the data or completing the write before returning from the method call. 
Lazy write operations: where the caller guarantees that it will never modify the
provided buffer and it can therefore be considered immutable. The target method is free to
maintain a reference to the buffer beyond the scope of the method call (e.g. until the write
operation completes).

/**
 * An output target for raw bytes. This interface provides semantics that support two types of
 * writing:
 *
 * <p><b>Traditional write operations:</b> (as defined by {@link java.io.OutputStream}) where the
 * target method is responsible for either copying the data or completing the write before returning
 * from the method call.
 *
 * <p><b>Lazy write operations:</b> where the caller guarantees that it will never modify the
 * provided buffer and it can therefore be considered immutable. The target method is free to
 * maintain a reference to the buffer beyond the scope of the method call (e.g. until the write
 * operation completes).
 */
@ExperimentalApi
public abstract class ByteOutput {
  
Writes a single byte.

Params:
  • value – the byte to be written
Throws:
  • IOException – thrown if an error occurred while writing
/**
   * Writes a single byte.
   *
   * @param value the byte to be written
   * @throws IOException thrown if an error occurred while writing
   */
  public abstract void write(byte value) throws IOException;

  
Writes a sequence of bytes. The ByteOutput must copy value if it will not be processed prior to the return of this method call, since value may be reused/altered by the caller. 
NOTE: This method MUST NOT modify the value. Doing so is a programming error and will lead to data corruption which will be difficult to debug. 
Params:
  • value – the bytes to be written
  • offset – the offset of the start of the writable range
  • length – the number of bytes to write starting from offset
Throws:
  • IOException – thrown if an error occurred while writing
/**
   * Writes a sequence of bytes. The {@link ByteOutput} must copy {@code value} if it will not be
   * processed prior to the return of this method call, since {@code value} may be reused/altered by
   * the caller.
   *
   * <p>NOTE: This method <strong>MUST NOT</strong> modify the {@code value}. Doing so is a
   * programming error and will lead to data corruption which will be difficult to debug.
   *
   * @param value the bytes to be written
   * @param offset the offset of the start of the writable range
   * @param length the number of bytes to write starting from {@code offset}
   * @throws IOException thrown if an error occurred while writing
   */
  public abstract void write(byte[] value, int offset, int length) throws IOException;

  
Writes a sequence of bytes. The ByteOutput is free to retain a reference to the value beyond the scope of this method call (e.g. write later) since it is considered immutable and is guaranteed not to change by the caller. 
NOTE: This method MUST NOT modify the value. Doing so is a programming error and will lead to data corruption which will be difficult to debug. 
Params:
  • value – the bytes to be written
  • offset – the offset of the start of the writable range
  • length – the number of bytes to write starting from offset
Throws:
  • IOException – thrown if an error occurred while writing
/**
   * Writes a sequence of bytes. The {@link ByteOutput} is free to retain a reference to the value
   * beyond the scope of this method call (e.g. write later) since it is considered immutable and is
   * guaranteed not to change by the caller.
   *
   * <p>NOTE: This method <strong>MUST NOT</strong> modify the {@code value}. Doing so is a
   * programming error and will lead to data corruption which will be difficult to debug.
   *
   * @param value the bytes to be written
   * @param offset the offset of the start of the writable range
   * @param length the number of bytes to write starting from {@code offset}
   * @throws IOException thrown if an error occurred while writing
   */
  public abstract void writeLazy(byte[] value, int offset, int length) throws IOException;

  
Writes a sequence of bytes. The ByteOutput must copy value if it will not be processed prior to the return of this method call, since value may be reused/altered by the caller. 
NOTE: This method MUST NOT modify the value. Doing so is a programming error and will lead to data corruption which will be difficult to debug. 
Params:
  • value – the bytes to be written. Upon returning from this call, the position of this buffer will be set to the limit
Throws:
  • IOException – thrown if an error occurred while writing
/**
   * Writes a sequence of bytes. The {@link ByteOutput} must copy {@code value} if it will not be
   * processed prior to the return of this method call, since {@code value} may be reused/altered by
   * the caller.
   *
   * <p>NOTE: This method <strong>MUST NOT</strong> modify the {@code value}. Doing so is a
   * programming error and will lead to data corruption which will be difficult to debug.
   *
   * @param value the bytes to be written. Upon returning from this call, the {@code position} of
   *     this buffer will be set to the {@code limit}
   * @throws IOException thrown if an error occurred while writing
   */
  public abstract void write(ByteBuffer value) throws IOException;

  
Writes a sequence of bytes. The ByteOutput is free to retain a reference to the value beyond the scope of this method call (e.g. write later) since it is considered immutable and is guaranteed not to change by the caller. 
NOTE: This method MUST NOT modify the value. Doing so is a programming error and will lead to data corruption which will be difficult to debug. 
Params:
  • value – the bytes to be written. Upon returning from this call, the position of this buffer will be set to the limit
Throws:
  • IOException – thrown if an error occurred while writing
/**
   * Writes a sequence of bytes. The {@link ByteOutput} is free to retain a reference to the value
   * beyond the scope of this method call (e.g. write later) since it is considered immutable and is
   * guaranteed not to change by the caller.
   *
   * <p>NOTE: This method <strong>MUST NOT</strong> modify the {@code value}. Doing so is a
   * programming error and will lead to data corruption which will be difficult to debug.
   *
   * @param value the bytes to be written. Upon returning from this call, the {@code position} of
   *     this buffer will be set to the {@code limit}
   * @throws IOException thrown if an error occurred while writing
   */
  public abstract void writeLazy(ByteBuffer value) throws IOException;
}