socket(+Domain, +Type, ?Stream)

Domain

Atom

Type

Atom

Stream

Atom, structure or variable.

Description

socket/3 is a direct link to the socket(2) socket system call. Domain is either unix or internet, type is stream or datagram. It creates a socket of the given type in the given domain and creates a stream associated with it. After the connection is established using bind/2, connect/2, listen/2 and/or accept/3, the stream can be used for input and output to communicate with other processes.

The unix domain can be used for communication between processes on the same machine, whereas the internet domain can connect any two machines. The stream type supports point-to-point reliable communication, whereas the datagram communication is a network-type communication with clear message boundaries, which, however, are not visible in ECLiPSe .

Note that in order to read data using read/1,2, it must have been written in Prolog term format (i.e. ended with a period and a blank space character). The output to sockets is buffered, so that data might be actually written only after a call to flush(Stream).

When instantiated, Stream must be the symbolic stream name (atom). The stream can also be specified as sigio(Stream). In this case the socket is created and in addition it is instructed to send the signal io each time new data appears in it.

Modes and Determinism

• socket(+, +, -) is det
• socket(+, +, +) is det

Exceptions

(5) type error

Stream is instantiated, but not to an atom or a sigio structure.

(5) type error

Domain or Type are instantiated but not to atoms.

(6) out of range

Domain or Type are atoms, but different from the accepted ones.

(170) system interface error

It was not possible to create the socket.

Examples

Success:
      socket(unix, stream, s).
      socket(internet, datagram, socket).

Error:
      socket(unix, stream, 1)       (Error 5).
      socket(telnet, datagram, X)   (Error 6).

See Also