VARLINK
Varlink is an interface description format and protocol that aims to make services accessible to both humans and machines in the simplest feasible way.
A varlink interface combines the classic UNIX command line options, STDIN/OUT/ERROR text formats, man pages, service metadata and provides the equivalent over a single file descriptor, a.k.a. “FD3”.
Varlink is plain-text, type-safe, discoverable, self-documenting, remotable, testable, easy to debug. Varlink is accessible from any programming environment. See the Ideals page for more. And everybody likes Screenshots.
A varlink interface has a reverse-domain name and specifies which methods the interface implements. Each method has named and typed input and output parameters. Complex types can be aliased with the type keyword to allow reusing them and to make method signatures easier to read. The interface also specifies the errors that may be returned from its method calls.
Everything can be documented by adding a comment immediately before it. The documentation is provided to clients as structured data on a well-known service interface.
