RPC-Libp2p Determining Request/Response data

[AgeManning]

Currently Requests/Responses are encoded with SSZ and sent across the wire.

SSZ requires a known schema in order to decode the serialized message.

For a message received on the libp2p-RPC stream, one needs to know whether the message is a request or response to decode the message appropriately. Messages could include a prefix bit, specifying which object should be decoded.

Is there a better way to handle this? Should we specify this in the spec?

[djrtwo]

Another alternative is to put requests and responses on a different libp2p protocol -- /eth/serenity/beacon/rpc/requests/1 vs /eth/serenity/beacon/rpc/responses/1.

What do you think @mslipper

[mslipper]

Hmm this is true. I'm kind of in favor of exploring alternative serialization formats/a message envelope to get around this issue. Having alternative libp2p protocols seems like a hack to get around a self-imposed limitation IMO.

[AgeManning]

I agree with @mslipper . Currently we (lighthouse) are building an SSZ req/resp object which has a prepended boolean which specifies whether its a request/response.
I think in our discussions we seem to favour pre-pending a byte/bit in the serialization to distinguish the two?

[AgeManning]

Closing to keep discussion in #871