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

Lick manages IPC ports, and the communication between Urbit applications and POSIX applications via these ports. Other vanes 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 byte4 bytesn bytes
versionjam size in bytesjamfile

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:

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