# info

> Tag 20: a client asks what a server is; the server sends exactly one response carrying, as JSON, the revision of this specification it implements, 2.3.0, and the capabilities it holds out, and the scope finishes.

Canonical: https://protocol.diverge.network/2.3.0/endpoints/info/
Specification revision: 2.3.0

A client opens the scope with a request whose payload is the tag byte
`20` and nothing more. The server sends exactly one response, whose
payload is one JSON object carrying `version`, the string `2.3.0`,
the revision of this specification, and `capabilities`, the object
the [Capabilities](/2.3.0/capabilities/) layer defines. The response finish
follows the response, and no frame follows the finish.

- **The request.** The request carries no parameter; the tag is the
  whole of it. [Request](/2.3.0/endpoints/info/request/) states its form.
- **The response.** The response carries the string `2.3.0` as
  `version`, and a server that implements this revision sends no
  other string; it carries as `capabilities` the capabilities the
  server holds out. [Response](/2.3.0/endpoints/info/response/) states its
  form.
- **No error.** This endpoint defines no error frame and no refusal.
  The scope carries exactly one response and the response finish.
- **Independence.** The request and its response depend on no other
  exchange. A client that does not know which revision a server
  implements, or which parts of the [Endpoints](/2.3.0/endpoints/) layer it
  serves, learns both from this exchange before it composes any other
  request.
- **The capabilities bind.** The capabilities the response carries
  are a fact of the server: every `info` response the server sends,
  on every connection, carries the same capabilities, and the server
  serves every request on every connection as they state.
  [Capabilities](/2.3.0/capabilities/) states what each capability binds
  the server to, and what the server sends for a request past a
  capability it does not hold out.