gRPC Protocol

1. Core concepts: unary RPC

   Single request and single response.

2. Streaming RPCs

   Server, client and bidirectional streaming.

3. Deadlines and timeouts

   Deadline propagation and DEADLINE_EXCEEDED.

4. Metadata

   Headers and trailers key-value pairs.

5. Status codes

   OK, CANCELLED, UNAVAILABLE and other status codes.

6. Error handling

   Error model and rich error details.

7. Wire protocol over HTTP/2

   Request and response framing: length-prefixed messages, headers and trailers.

8. Authentication

   TLS, ALTS and token-based credentials.

9. Cancellation

   Cancelling in-flight RPCs.

10. Keepalive

    HTTP/2 PING keepalive settings.

11. Retry and health checking

    Retry policies and hedging.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.