[Web-SIG] help with the implementation of a WSGI middleware

[Manlio Perillo]

Phillip J. Eby ha scritto:
> At 11:21 PM 7/7/2008 +0200, Manlio Perillo wrote:
>> So this is not a "bad" middleware, IMHO.
> 
> True, but it's part of the application, rather than being transparent.
> 

Ok, I agree.

Does this means that such non trasparent middlewares must not be 
inserted inside the "gateway middleware stack", even if this is done 
only as a convenience (so that you don't have to use a decorator for 
every functions)?


>> By the way, a middleware that is responsible for user authentication:
>> http://hg.mperillo.ath.cx/wsgix/file/tip/wsgix/auth/http_middleware.py
>>
>> is a good middleware?
>>
>> To keep it simple, the middleware check if there is an authorization 
>> header and the credentials are correct.
>>
>> If this is true, execute the WSGI application (setting 
>> environ['REMOTE_USER']), otherwise return a forbidden response.
> 
> Right - that's transparent middleware: the application doesn't need to 
> know it's there.
> 

I think that it's rather subtle.
If you remove the middleware, the application is no more able to handle 
authenticated user.

This is not a problem, the application is still able to work correctly, 
but the same applies to my messages middleware, IMHO.

> 
>>> Under WSGI 2.0, it's even easier since you don't need decorators to 
>>> manipulate your response: you can just "return someapi(...)" where 
>>> the "..." is whatever you were going to return directly.
>>
>> return someapi() from inside the WSGI application?
> 
> Yes.
> 

Do you have a working example?

Also, can you post an example of a middleware that needs to replace the 
environ dictionary?



Thanks   Manlio Perillo