Re: Inviting feedback on my proposed "ASGI" spec

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> On 10 Mar 2016, at 00:34, Andrew Godwin <[email protected]> wrote:
>=20
> To that end, I did some work to make the underlying mechanism Django =
Channels uses into more of a standard, which I have codenamed ASGI; =
while initially I intended for it to be a Django documented API, as I've =
gone further with the project I've come to believe it could be useful to =
the Python community at large.
>=20

Andrew,

Thanks for this work! I=E2=80=99ve provided some proposed changes as =
pull requests against the channels repository. I=E2=80=99ll ignore those =
for the rest of the email: we can discuss them on GitHub.

I also have a few more general notes. I didn=E2=80=99t make PRs for =
these, mostly because they=E2=80=99re too =E2=80=9Cvague=E2=80=9D as =
feedback goes to be concretely handled by me.

First, your HTTP section has request headers serialized to a dict and =
response headers serialized to a list of tuples. I=E2=80=99m not sure =
how I feel about that asymmetry: it might be cleaner just to use =
lists-of-tuples in both places and allow application frameworks to =
handle translation to dictionary if they require it.

Second, if it were me I=E2=80=99d remove the `status_text` field on the =
`Response` object. Custom status text is a terrible misfeature =
(especially as HTTP/2 doesn=E2=80=99t support it), and in 99% of cases =
you=E2=80=99re just wasting data by repeatedly sending the default =
phrase that the server already knows.

Third, you=E2=80=99re currently sending header fields with unicode names =
and byte string values. That=E2=80=99s understandable, but I wonder if =
it=E2=80=99s worthwhile trying to limit the behaviour of compliant =
servers in encoding/decoding those header fields. For example, you could =
assert that the unicode header names will always use the Latin-1 codec =
when encoding/decoding. This is mostly me being paranoid about poorly =
written apps/servers issuing bad bytes onto the network. I should note =
that RFC 7230 strictly limits header names to US-ASCII, but Latin-1 =
would be the defensive choice against already-badly-written apps.

Your section on server push is great, whoever wrote that is clearly a =
genius. ;)

You define web socket data frames with an incrementing counter from =
zero, but also note that the maximum integer size is Python=E2=80=99s =
sys.maxint (you actually aren=E2=80=99t that clear about it, which might =
be a good idea). While this is *probably* not a problem, you may want to =
note that really long running or active web socket connections are at =
risk of exhausting the =E2=80=98order=E2=80=99 counter, and define a =
behaviour if that happens.

Otherwise, this is an interesting specification. I=E2=80=99m certainly =
open to helping push it through the PEP process if you=E2=80=99d like =
assistance with that.

Cory

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