[Web-SIG] Questions/suggestions on 'wsgi.file_wrapper'

[Mike Orr]

Phillip J. Eby wrote:

>At 11:25 AM 12/21/2005 -0500, Jim Fulton wrote:
>
>  
>
>>Here are some questions and sugesstions on the 'wsgi.file_wrapper'
>>part of the WSGI API:
>>
>>1. Does this need to be optional?  It seems that it would be
>>    easy for any server to provide this, it would be nice for
>>    applications to be able to rely in it.
>>    
>>
>
>It's intentionally optional because its presence signifies that the server 
>can do things *better* than the application, if and only if the object is a 
>"real" operating system file or other "special" object.  The only reason 
>the spec requires only a "file-like" object rather than an object with a 
>valid "fileno()" method, is because somebody wanted to support Jython 
>objects wrapping Java sio(?) objects, for a Java equivalent of sendfile().
>  
>

Allowing a file-like object like StringIO also allows the environment to 
be pickled and sent to another process.  This lets a Python web server 
talk directly to a Python application server using WSGI, rather than 
having to kludge through SCGI and then repackage it to WSGI.  I don't 
know of any web servers that do this yet but it would be a shame to lose 
the capability.

If we require a file object, the environment becomes non-pickleable 
because you can't serialize an open file.  SCGI uses passfd, which 
somehow works, but not on Windows.  If we require .fileno(), one could 
have an object that quickly writes the content to a file and passes that 
fileno, but I don't see what that gains.

-- Mike Orr