[Web-SIG] Collating follow-up on the future of WSGI

Thu Jan 21 01:24:25 EST 2016

I am still confused as to why you keep talking as if you seemingly are trying to force extensions to the existing WSGI specification into the core WSGI specification when an alternative has already been cited.

Extensions and the process for describing them and getting them accepted, plus the appropriate WSGI environ prefix, as has been mentioned before, is what is covered by:

    http://wsgi.readthedocs.org/en/latest/specifications.html <http://wsgi.readthedocs.org/en/latest/specifications.html>

Being an extension means it is entirely optional for a WSGI server to try and implement it, thus allowing WSGI servers/adapters that cannot implement something to skip them. They stand as separate documents and would never become part of the core WGSI PEP.

Is there an issue with doing extensions per the process, and in the WSGI environ namespace, that was outlined in that URL? You seem to be suggesting a completely new way of handling extensions and ignoring what was laid down before.

So no one is saying you can’t have extensions, and that separate process gives you all the scope you need to do it.

In drafting your specification just fit it reference to what is described in that URL, using ‘x-wsgiorg.’ prefix keys.

Graham

> On 21 Jan 2016, at 4:13 PM, Benoit Chesneau <bchesneau at gmail.com> wrote:
> 
> I am not speaking about websockets.  You could use it for SSE, or some apps could use the Upgrade header to upgrade from http to their own protocol etc... The only discussion i saw about websockets are about the addition of an async api or an external api. I am not describing that. I am speaking about providing a low level abstraction like wsgi.input but adding to it the support of output. (I was referring to wsgi.multithread...). This low level interface would allow anyone to provide its own implementation(server) or usage (application) still acting as a *gateway* .
> 
> Also who are "we"? I am starting to think the discussion is already done and only obscure details like the content_length or headers encoding should be discussed. The RAW_SOCKET have been added on demand of the gunicorn users. Such thing also exist in things like cherrypy if I remember. A lot of code around have been created over it. So before deciding it's unworkable or whatever I strongly invite you to consider it as an addition to the environ. And since some servers need to pass the data differently I then suggest a Resource object on which you can read and write and eventually poll. This is not a websocket but more a proxy ressource to the client connexion. I will come back asap with a small spec.
> 
> I also propose a second addition to the protocol that formalize the addition of extensions to the protocol by the servers if they want to. Having for example something like "`wsg.extensions` . Such addition would help anyone to experiment changes over the wsgi before making such changes in the specification by itself possibly.
> 
> I think we have a good opportunity to extend the WSGI specification to allow the users to take over the new challenges on the web without forcing them to use a concurrency mode or skip completely the WSGI spec. The interest I see in WSGI is its simplicity and low level interface allowing users to build whatever they want over it. The different workers and their support of different concurrency models and framework  in gunicorn let me think it is possible. Are the participants of this thread ready to discuss it? 
> 
> - benoît
> 
> On Wed, 20 Jan 2016 at 23:37, Graham Dumpleton <graham.dumpleton at gmail.com <mailto:graham.dumpleton at gmail.com>> wrote:
>> On 21 Jan 2016, at 9:27 AM, Benoit Chesneau <bchesneau at gmail.com <mailto:bchesneau at gmail.com>> wrote:
>> 
>> again. any server can do such implementation if we create a new Resource abstraction. This abstraction would expose a common api to read and write. The implementation would be specific to the server.
> 
> If you mean not exposing the raw socket and having a separate high level API for implementing something like WebSocket this was already talked about. The suggestion was that it should not be a part of WSGI. Develop that API independently with no link to WSGI. The idea of upgrading from WSGI to a different API isn’t practical for various WSGI servers as it isn’t possible to unwind the state of the connection path created to get to point of handling the WSGI application. The better scenario is that the switch to an alternate WebSocket API is handled completely within the web server however it needs to handle it, when it needs to handle it, and not be reliant on going into a WSGI application which then says, oh, I actually need that to be WebSocket.
> 
>> Now like we have wsgi.thread I would instead suggest to add a system of capability or extension  like in smtp, imap, ... so the servers that implement a specific extension can legally published it. Would it work for you?
> 
> Since there is nothing in WSGI environ called wsgi.thread now I have no idea what you are really suggesting here.
> 
> Graham
> 
>> benoit
>> 
>> On Wed, 20 Jan 2016 at 21:28, Graham Dumpleton <graham.dumpleton at gmail.com <mailto:graham.dumpleton at gmail.com>> wrote:
>> 
>>> On 21 Jan 2016, at 2:48 AM, Benoit Chesneau <bchesneau at gmail.com <mailto:bchesneau at gmail.com>> wrote:
>>> 
>>> 
>>> 
>>> On Wed, Jan 20, 2016 at 1:57 AM Robert Collins <robertc at robertcollins.net <mailto:robertc at robertcollins.net>> wrote:
>>> On 20 January 2016 at 12:04, Benoit Chesneau <bchesneau at gmail.com <mailto:bchesneau at gmail.com>> wrote:
>>> 
>>> >
>>> > not at all. But I made the assumption that the wsgi server maintained a
>>> > thread directly or not where the python application is running .
>>> >
>>> > In any case there is some sort of wrapping done in the same thread/process
>>> > where the python application is running. And then nothing stop to give the
>>> > socket away to the application and tell to the server to stop to communicate
>>> > with it.
>>> 
>>> What socket?
>>> 
>>> Data could be being passed by shm, for instance.
>>> 
>>> -Rob
>>> 
>>> 
>>> While shared memory would be quite a bad idea, then why not. I still don't see why having a way to upgrade the connection can't be done.
>>> 
>>> Call it I/O resource or Socket, the issue is the same. At the end nothing stop the server to pass the control to the app. If we forget the socket (which is btw the simplest design) then the server could stop to control the I/O resource when the application ask it to do it. At some point either a garbage collection or a basic resource return/claim flow could be used to definitely free the resource.
>>> 
>>> The thing behind that is that it would allow the WSGI spec to only focus on providing a strict gateway workflow without forcing the application to adopt a concurrency model aync or not.
>> 
>> No one has said you cannot do it. because though it is only able to be implemented in a subset of WSGI servers/adapters, then it doesn’t seem appropriate that it be a part of the core WSGI specification.
>> 
>> This is the role of a WSGI extension as found at:
>> 
>>     http://wsgi.readthedocs.org/en/latest/specifications.html <http://wsgi.readthedocs.org/en/latest/specifications.html>
>> 
>> So go talk to the authors of uWSGI, and the other couple of packages available for trying to plug these into some of the pure Python based WSGI servers and come to an agreement between yourselves as to a standard way of doing it and the extension specification can be added to the wsgi.org <http://wsgi.org/> site.
>> 
>> Graham
>> 

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