4.1. Specifying the Use of HTTP

4.1. Specifying the Use of HTTP

When an application using HTTP is specified, the first step is to state that HTTP is being used and what version(s) of the protocol are applicable. Applications SHOULD NOT specify support for an HTTP version; instead, they SHOULD use the version-independent identifiers in the "Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry.

For example:

This application uses HTTP [HTTP].

It's also possible to specify a minimum version:

This application uses HTTP [HTTP]. Implementations MUST support HTTP/2 [HTTP/2] or greater.

Applications that require a specific version of HTTP can also be specified:

This application uses HTTP/2 [HTTP/2].

It's preferable to allow future versions of HTTP to be used, as they will offer improved performance, security, and features.