[/
 / Copyright (c) 2003-2010 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 /
 / Distributed under the Boost Software License, Version 1.0. (See accompanying
 / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 /]

[section:DatagramSocketService Datagram socket service requirements]

A datagram socket service must meet the requirements for a [link
boost_asio.reference.SocketService socket service], as well as the
additional requirements listed below.

In the table below, `X` denotes a datagram socket service class for protocol
[link boost_asio.reference.Protocol `Protocol`], `a` denotes a value of type
`X`, `b` denotes a value of type `X::implementation_type`, `e` denotes a value
of type `Protocol::endpoint`, `ec` denotes a value of type `error_code`, `f`
denotes a value of type `socket_base::message_flags`, `mb` denotes a value
satisfying [link boost_asio.reference.MutableBufferSequence mutable buffer
sequence] requirements, `rh` denotes a value meeting [link
boost_asio.reference.ReadHandler `ReadHandler`] requirements, `cb` denotes a
value satisfying [link boost_asio.reference.ConstBufferSequence constant
buffer sequence] requirements, and `wh` denotes a value meeting [link
boost_asio.reference.WriteHandler `WriteHandler`] requirements.

[table DatagramSocketService requirements
  [[expression] [return type] [assertion/note\npre/post-condition]]
  [
    [`a.receive(b, mb, f, ec);`]
    [`size_t`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Reads one or more bytes of data from a connected socket `b`.\n
      \n
      The mutable buffer sequence `mb` specifies memory where the data should
      be placed. The operation shall always fill a buffer in the sequence
      completely before proceeding to the next.\n
      \n
      If successful, returns the number of bytes read. Otherwise returns `0`.
    ]
  ]
  [
    [`a.async_receive(b, mb, f, rh);`]
    [`void`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Initiates an asynchronous operation to read one or more bytes of data
      from a connected socket `b`. The operation is performed via the
      `io_service` object `a.io_service()` and behaves according to [link
      boost_asio.reference.asynchronous_operations asynchronous operation]
      requirements.\n
      \n
      The mutable buffer sequence `mb` specifies memory where the data should
      be placed. The operation shall always fill a buffer in the sequence
      completely before proceeding to the next.\n
      \n
      The implementation shall maintain one or more copies of `mb` until such
      time as the read operation no longer requires access to the memory
      specified by the buffers in the sequence. The program must ensure the
      memory is valid until:\n
      \n
      [mdash] the last copy of `mb` is destroyed, or\n
      \n
      [mdash] the handler for the asynchronous operation is invoked,\n
      \n
      whichever comes first.\n
      \n
      If the operation completes successfully, the `ReadHandler` object
      `rh` is invoked with the number of bytes transferred. Otherwise it is
      invoked with `0`.
    ]
  ]
  [
    [`a.receive_from(b, mb, e, f, ec);`]
    [`size_t`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Reads one or more bytes of data from an unconnected socket `b`.\n
      \n
      The mutable buffer sequence `mb` specifies memory where the data should
      be placed. The operation shall always fill a buffer in the sequence
      completely before proceeding to the next.\n
      \n
      If successful, returns the number of bytes read. Otherwise returns `0`.
    ]
  ]
  [
    [`a.async_receive_from(b, mb, e, f, rh);`]
    [`void`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Initiates an asynchronous operation to read one or more bytes of data
      from an unconnected socket `b`. The operation is performed via the
      `io_service` object `a.io_service()` and behaves according to [link
      boost_asio.reference.asynchronous_operations asynchronous operation]
      requirements.\n
      \n
      The mutable buffer sequence `mb` specifies memory where the data should
      be placed. The operation shall always fill a buffer in the sequence
      completely before proceeding to the next.\n
      \n
      The implementation shall maintain one or more copies of `mb` until such
      time as the read operation no longer requires access to the memory
      specified by the buffers in the sequence. The program must ensure the
      memory is valid until:\n
      \n
      [mdash] the last copy of `mb` is destroyed, or\n
      \n
      [mdash] the handler for the asynchronous operation is invoked,\n
      \n
      whichever comes first.\n
      \n
      The program must ensure the object `e` is valid until the handler
      for the asynchronous operation is invoked.\n
      \n
      If the operation completes successfully, the `ReadHandler` object
      `rh` is invoked with the number of bytes transferred. Otherwise it is
      invoked with `0`.
    ]
  ]
  [
    [`a.send(b, cb, f, ec);`]
    [`size_t`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Writes one or more bytes of data to a connected socket `b`.\n
      \n
      The constant buffer sequence `cb` specifies memory where the data to be
      written is located. The operation shall always write a buffer in the
      sequence completely before proceeding to the next.\n
      \n
      If successful, returns the number of bytes written. Otherwise returns `0`.
    ]
  ]
  [
    [`a.async_send(b, cb, f, wh);`]
    [`void`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Initiates an asynchronous operation to write one or more bytes of data to
      a connected socket `b`. The operation is performed via the `io_service`
      object `a.io_service()` and behaves according to [link
      boost_asio.reference.asynchronous_operations asynchronous operation]
      requirements.\n
      \n
      The constant buffer sequence `cb` specifies memory where the data to be
      written is located. The operation shall always write a buffer in the
      sequence completely before proceeding to the next.\n
      \n
      The implementation shall maintain one or more copies of `cb` until such
      time as the write operation no longer requires access to the memory
      specified by the buffers in the sequence. The program must ensure the
      memory is valid until:\n
      \n
      [mdash] the last copy of `cb` is destroyed, or\n
      \n
      [mdash] the handler for the asynchronous operation is invoked,\n
      \n
      whichever comes first.\n
      \n
      If the operation completes successfully, the `WriteHandler` object `wh`
      is invoked with the number of bytes transferred. Otherwise it is invoked
      with `0`.
    ]
  ]
  [
    [``
      const typename Protocol::endpoint& u = e;
      a.send_to(b, cb, u, f, ec);
    ``]
    [`size_t`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Writes one or more bytes of data to an unconnected socket `b`.\n
      \n
      The constant buffer sequence `cb` specifies memory where the data to be
      written is located. The operation shall always write a buffer in the
      sequence completely before proceeding to the next.\n
      \n
      If successful, returns the number of bytes written. Otherwise returns `0`.
    ]
  ]
  [
    [``
      const typename Protocol::endpoint& u = e;
      a.async_send(b, cb, u, f, wh);
    ``]
    [`void`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Initiates an asynchronous operation to write one or more bytes of data to
      an unconnected socket `b`. The operation is performed via the `io_service`
      object `a.io_service()` and behaves according to [link
      boost_asio.reference.asynchronous_operations asynchronous operation]
      requirements.\n
      \n
      The constant buffer sequence `cb` specifies memory where the data to be
      written is located. The operation shall always write a buffer in the
      sequence completely before proceeding to the next.\n
      \n
      The implementation shall maintain one or more copies of `cb` until such
      time as the write operation no longer requires access to the memory
      specified by the buffers in the sequence. The program must ensure the
      memory is valid until:\n
      \n
      [mdash] the last copy of `cb` is destroyed, or\n
      \n
      [mdash] the handler for the asynchronous operation is invoked,\n
      \n
      whichever comes first.\n
      \n
      If the operation completes successfully, the `WriteHandler` object `wh`
      is invoked with the number of bytes transferred. Otherwise it is invoked
      with `0`.
    ]
  ]
]

[endsect]