FUDI
FUDI is a networking protocol used by the Pure Data patching language invented by Miller Puckette. It is a string based protocol in which messages are separated by semicolons. Messages are made up of tokens separated by whitespaces, and numerical tokens are represented as strings.
Format
FUDI is a packet oriented protocol.
Each message consists of one or more atoms, separated by one or more whitespace characters, and it's terminated by a semicolon character.
An atom is a sequence of one or more characters; whitespaces inside atoms can be escaped by the backslash (ascii 92) character (see Examples below).
A whitespace is either a space (ascii 32), a tab (ascii 9) or a newline (ascii 10).
A semicolon (ascii 59) is mandatory to terminate (and send) a message. A newline is just treated as whitespace and not needed for message termination.
Fudi is also the Swiss German word for bottom.
Implementations
pdsend / pdreceive
Those command-line tools are distributed with the software Pure Data. They are meant to be used with their counterparts, the classes [netsend] / [netreceive] of Pd.
[netsend] / [netreceive]
Those classes can be used to transport Pd-messages over a TCP or UDP socket. Both are part of Pd-vanilla.
[netserver] / [netclient]
Those are part of maxlib and allow bidirectional connections of multiple clients with one server.
Example messages
test/blah 123.45314;
my-slider 12;
hello this is a message;
this message continues in the following line;
you; can; send; multiple messages; in a line;
this\ is\ one\ whole\ atom;
this_atom_contains_a\ newline_character_in_it;