Trailers about http2-spec HOT 3 CLOSED

I think of this as being about the mapping of the protocol primitives to the HTTP semantics.

As an example use-case for sending metadata during the stream, imagine providing a signed cryptographic hash of content via the HEADERS frame in a session speaking in the clear over port 80 periodically.

This may imply that we wish to have two different ways of providing metadata (perhaps signaled via a flag in the HEADERS frame?), one which is provided to the application layer, and another which exists to provide data to mechanisms below.

Basically, I think we should define that the first HEADERS are equivalent to request headers, and say that the rest of any HEADERS sent on a stream should be ignored at the HTTP semantic layer (at least for now).

from http2-spec.

Not convinced that an additional flag is necessary. The initial request/response headers ought to be limited to the initial Headers+Priorities frame and possibly a single header continuation frame past last. All other headers frames ought to be passed on and made available to higher levels in the stack with only, perhaps, a few limited exceptions.

from http2-spec.

Discussed at SF Interim.

For first implementation draft, only the first headers (pre-data) are mapped to HTTP headers; we'll discuss trailers after.

from http2-spec.