Thorns

A thorn is the basic working module within Cactus. All user supplied code goes into thorns, which are, by and large, independent of each other. Thorns communicate with each other via calls to the flesh API, plus, more rarely, custom APIs of other thorns.

The connection from a thorn to the flesh, or to other thorns, is specified in configuration files which are parsed at compile time and used to generate glue code which encapsulates the external appearance of a thorn.

Thorn names must be (case independently) unique, must start with a letter, can only contain letters, numbers or underscores, and must contain 27 characters or less. In addition, a thorn cannot have the name doc, this is reserved for arrangement documentation. Arrangement names which start with a `#', or finish with `~' or `.bak' will be ignored.