Creating a shim for tornado with Autobahn|Python

[Evan Bolyen]

Hello!

I want to start by saying what an awesome protocol (WAMP) and implementation you guys have!

We would really love to use autobahn as it has already made our prototype nearly trivial to implement. The one hangup is we need to implement file upload/download using HTTP. Ideally we would use twisted, however our project is python3. I've done a lot of googling about the feasibility of creating a shim for tornado and found these :

http://stackoverflow.com/questions/20657935/using-autobahn-twisted-to-establish-a-websocket-connection-in-tornado-http-handl

https://github.com/tavendo/AutobahnPython/issues/281

It looks like it should be possible to create a little bit of code to interface the event loop of tornado with the WAMP logic of autobahn, but I want to clarify I couple of implementation details before I get too invested in this.

Tornado supports using an asyncio event loop, so in principle (I hope), both packages should be able to work together. My question is, would the integration then be as simple as creating a class which subclassed both the WampWebsocketServerFactory and tornado's WebSocketHandler and provided a mapping? Or am I looking at the wrong implementation layer and I need to go deeper?

Thanks for your time!

-Evan

[Tobias Oberstein]

Hi Evan,

> I want to start by saying what an awesome protocol (WAMP) and
> implementation you guys have!

Thanks;)

> We would really love to use autobahn as it has already made our
> prototype nearly trivial to implement. The one hangup is we need to
> implement file upload/download using HTTP. Ideally we would use twisted,
> however our project is python3. I've done a lot of googling about the

What about using asyncio? The latter is already supported by
AutobahnPython and runs on Python 3.

> feasibility of creating a shim for tornado and found these :
>
> http://stackoverflow.com/questions/20657935/using-autobahn-twisted-to-establish-a-websocket-connection-in-tornado-http-handl

This is running a Twisted-like event loop _under_ Tornado

http://www.tornadoweb.org/en/stable/twisted.html

I haven't tried that. Probably AutobahnPython works out of the box.
However, you app will then depend on both Tornado and Twisted.

>
> https://github.com/tavendo/AutobahnPython/issues/281
>
>
> It looks like it should be possible to create a little bit of code to
> interface the event loop of tornado with the WAMP logic of autobahn, but
> I want to clarify I couple of implementation details before I get too
> invested in this.
>
>
> Tornado supports using an asyncio event loop, so in principle (I hope),
> both packages should be able to work together. My question is, would the
> integration then be as simple as creating a class which subclassed both
> the WampWebsocketServerFactory and tornado's WebSocketHandler and
> provided a mapping? Or am I looking at the wrong implementation layer
> and I need to go deeper?

The way AutobahnPython supports multiple underlying networking
frameworks is actually already using shims/mixins. E.g. all asyncio
specific support code is here:

https://github.com/tavendo/AutobahnPython/tree/master/autobahn/autobahn/asyncio

If you want to add Tornado support, you would need to implement 3 files

autobahn/tornado/__ini__.py
autobahn/tornado/websocket.py
autobahn/tornado/wamp.py

using

http://www.tornadoweb.org/en/stable/concurrent.html#tornado.concurrent.Future

as the asynchronous abstraction.

Doing above would result in your app only depend on AutobahnPython
besides Tornado (not Twisted nor asyncio), and AutobahnPython's WAMP
implementation would use AutobahnPython's WebSocket implementation.

Is that would you are looking for?

Cheers,
/Tobias

>
>
> Thanks for your time!
>
> -Evan
>

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