Re: [quicwg/base-drafts] NUM_PLACEHOLDERS MUST NOT be zero (#2753)

Dmitri Tikhonov <> Fri, 24 May 2019 12:31 UTC

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Subject: Re: [quicwg/base-drafts] NUM_PLACEHOLDERS MUST NOT be zero (#2753)
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> These changes would essentially bring back what we observe in HTTP/2 - server that ignore placeholders would just ignore.

Introduction of placeholders is the backward-compatible part of HTTP/3 prioritization changes: if the client does not use placeholders it can use HTTP/3 priorities without placeholders just as in HTTP/2.  In other words, the clients can ignore placeholders as well.

I agree that it seems that a server SHOULD provide some sensible value.  My guess -- based on some of my mental models -- is that this number should be between N/2 and N, where N is the maximum number of parallel requests the server allows.

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