Lick

Urbit's inter-process communication (IPC) module.

Lick manages IPC ports, and the communication between Urbit applications and POSIX applications via these ports. Other Arvo modules and applications ask Lick to open an IPC port, notify it when something is connected or disconnected, and transfer data between itself and the Unix application.

The IPC ports Lick creates are Unix domain sockets (AF_UNIX address family) of the SOCK_STREAM type.

The format of the full message with header and data sent to and from the socket is as follows:

1 byte	4 bytes	n bytes
version	jam size in bytes	jamfile

The version is currently 0.

The +jamfile contains a pair of $mark and $noun. The process on the host OS must therefore strip the first 5 bytes, +cue the jamfile, check the mark, and (most likely) convert the noun into a native data structure.

Here are some libraries that can cue/jam:

• pynoun

• nockjs

• Rust Noun

Lick has no novel data types in its API apart from $name, which is just a path representing the name of a socket.