On Fri, Jun 9, 2017 at 8:22 PM, Tom Christie <[email protected]> wrote:
> Figure I may as well show the sort of thing I'm thinking wrt. a more
> constrained consumer callable interface...
>
> * A callable, taking two arguments, 'message' & 'channels'
> * Message being JSON-serializable python primitives.
> * Channels being a dictionary of str:channel
> * Channel instances expose `.send()`, `.receive()` and `.name` interfaces.
>
> Extensions such as groups/statistics/flush would get expressed instead as
> channel interfaces,
> eg. a chat example...
>
> def ws_connected(message, channels):
> channels['reply'].send({'accept': True})
> channels['groups'].send({
> 'group': 'chat',
> 'add': channels['reply'].name
> })
>
> def ws_receive(message, channels):
> channels['groups'].send({
> 'group': 'chat',
> 'send': message['text']
> })
>
> def ws_disconnect(message, channels):
> channels['groups'].send({
> 'group': 'chat',
> 'discard': channels['reply'].name
> })
>
So is the channels object just a place to stuff different function
handlers? Why not just pass the channel layer there and use the API on that
directly? e.g.:
channel_layer.group_send("chat", message["text"])
I was thinking more like:
def handler(channel_layer, channel_name, message):
...
And then frameworks can do per-channel-name dispatch if they like, and use
the channel layer for the send/group methods.
>
> My thinking at the moment is that there isn't any great way of supporting
> both asyncio and sync implementations under the same interface.
> If you're in asyncio land, it makes sense to *only* expose awaitable
> channel operations as you don't ever want to be able to block the task pool.
>
> I think the best you can really do is express two distinct modes of
> interface.
>
> sync: (callable interface, blocking send/receive interface)
> asyncio (coroutine interface, coroutine send/receive interface)
>
> Presumably the equivalent would be true of eg. twisted.
>
> (There's a couple of diff things you can do to bridge from the asyncio
> interface -> sync interface if that's useful)
>
Yup, you can't make cross-compatible ones. This is why ASGI right now has a
receive() method (sync), receive_twisted(), and receive_async(), because
all three have different signatures. I'm hopeful the Twisted and asyncio
ones could be merged, though.
Andrew
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