udp_receive/4

Documentation
- Reference manual
- Packages
  - SWI-Prolog C-library
    - library(socket): Network socket (TCP and UDP) library
      - UDP protocol support
        
        udp_socket/1
        
        udp_receive/4
        
        udp_send/4

Availability::- use_module(library(socket)).(can be autoloaded)

udp_receive(+Socket, -Data, -From, +Options)

Wait for and return the next datagram. The data is returned as a Prolog string object (see string_to_list/2). From is a term of the format ip(A,B,C,D):Port indicating the sender of the message. Socket can be waited for using wait_for_input/3. Defined Options:

as(+Type): Defines the returned term-type. Type is one of atom, codes or string (default).
max_message_size(+Size): Specify the maximum number of bytes to read from a UDP datagram. Size must be within the range 0-65535. If unspecified, a maximum of 4096 bytes will be read.

The typical sequence to receive UDP data is:

receive(Port) :-
        udp_socket(S),
        tcp_bind(S, Port),
        repeat,
            udp_receive(Socket, Data, From, [as(atom)]),
            format('Got ~q from ~q~n', [Data, From]),
            fail.