API Protos
This folder contains the schema of the configuration model for Google's internal API serving platform, which handles routing, quotas, monitoring, logging, and the like.
Google refers to this configuration colloquially as the "service config",
and the service.proto file in this directory is the entry point for
understanding these.
Using these protos
To be honest, we probably open sourced way too much of this (basically by
accident). There are a couple files in here you are most likely to be
interested in: http.proto, documentation.proto, auth.proto, and
annotations.proto.
HTTP and REST
The http.proto file contains the Http message (which then is wrapped
in an annotation in annotations.proto), which provides a specification
for REST endpoints and verbs (GET, POST, etc.) on RPC methods.
We recommend use of this annotation for describing the relationship
between RPCs and REST endpoints.
Documentation
The documentation.proto file contains a Documentation message which
provides a mechanism to fully describe an API, allowing a tool to build
structured documentation artifacts.
Authentication
The auth.proto file contains descriptions of both authentication rules
and authentication providers, allowing you to describe what your services
expect and accept from clients.