Response should include dictionary used for encoding - raised by Martin Thomson

[pmeenan]

I don't understand how a client determines which dictionary was used by the server. It seems like the response depends on the request, which is fragile (and doesn't allow clients to advertise multiple dictionaries, which seems likely with Use-As-Dictionary as it is).

Original listserv response
cc @martinthomson

Moved from private ID issue #3

[pmeenan]

For identifying the dictionary, it's worth noting that the spec requires that the client advertise a SINGLE dictionary that it supports but yes, the response depends on the dictionary identified in the request. This also helps with minimizing the variants that caches would need to store since the response needs to be varied on the request's available dictionary (and multiple would explode the permutations). It wouldn't hurt to echo the dictionary hash in the response which would allow for other mechanisms of advertising dictionaries but that also carries the cost of complicating the vary logic (would need to vary based on whatever request header was used to negotiate the dictionary that ended up being used).

Listserv response

[pmeenan]

Dictionary hash used is now in the response headers.