UNIX — local communication domain protocol
The local communication domain protocol,
commonly referred to in the industry as the
Unix domain protocol,
utilizes the path name address format and the
This protocol can be used
as an alternative to the Internet protocol family (TCP/IP or
for communication between processes executing on the same node.
It has a significant throughput advantage when compared with local
loopback, due primarily to its much lower code execution overhead.
Data is looped back at the protocol layer (OSI
Level 4), rather than at the driver layer (OSI
is supported in the
implementation of the local communication domain protocol
does not support the
socket addresses are path names.
They are limited to 92 bytes in length,
including a terminating null byte.
socket utilize an addressing structure called
Pointers to this structure should be used in all
socket system calls wherever they require a pointer to a
The include file
defines this addressing structure.
Within this structure are two notable fields.
The first is
which must be set to
The next is
which is the null-terminated character string
that specifies the path name of the file
associated with the socket (for example,
Only the passive (listening) socket must bind to an address.
The active socket connects to that address, but it does not
need an address of its own.
For additional information on using
sockets for interprocess communication, refer to the
BSD Sockets Interface Programmer's Guide.
Socket Buffer Size
For stream and datagram sockets,
the maximum send and receive buffer size is 262142 bytes.
The default buffer size is 32768 bytes.
The send and receive buffer sizes can be altered by using the
options of the
was developed by the University of California, Berkeley.