GNU Info

(libc.info)Communication Styles

---

Next: Socket Addresses Prev: Socket Concepts Up: Sockets

---

Enter node , (file) or (file)node

Communication Styles
====================

   The GNU library includes support for several different kinds of
sockets, each with different characteristics.  This section describes
the supported socket types.  The symbolic constants listed here are
defined in `sys/socket.h'.

 - Macro: int SOCK_STREAM
     The `SOCK_STREAM' style is like a pipe (Note: Pipes and FIFOs).
     It operates over a connection with a particular remote socket and
     transmits data reliably as a stream of bytes.

     Use of this style is covered in detail in Note: Connections.

 - Macro: int SOCK_DGRAM
     The `SOCK_DGRAM' style is used for sending individually-addressed
     packets unreliably.  It is the diametrical opposite of
     `SOCK_STREAM'.

     Each time you write data to a socket of this kind, that data
     becomes one packet.  Since `SOCK_DGRAM' sockets do not have
     connections, you must specify the recipient address with each
     packet.

     The only guarantee that the system makes about your requests to
     transmit data is that it will try its best to deliver each packet
     you send.  It may succeed with the sixth packet after failing with
     the fourth and fifth packets; the seventh packet may arrive before
     the sixth, and may arrive a second time after the sixth.

     The typical use for `SOCK_DGRAM' is in situations where it is
     acceptable to simply re-send a packet if no response is seen in a
     reasonable amount of time.

     Note: Datagrams, for detailed information about how to use
     datagram sockets.

 - Macro: int SOCK_RAW
     This style provides access to low-level network protocols and
     interfaces.  Ordinary user programs usually have no need to use
     this style.