[Zope-dev] Zope2 and WSGI

[Tres Seaver]

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Martin Aspeli wrote:
> Tres Seaver wrote:
> 
>> After a question on the repoze list about running Zope 2.12.x behind a
>> WSGI server, I went to try that out.  I came up with a minimal .wsgi
>> file to run behind mod_wsgi::
>>
>>   $ cat src/Zope2/utilities/skel/bin/zope2.wsgi.in
>>   from Zope2.Startup.run import configure
>>   from Zope2 import startup
>>   configure('<<INSTANCE_HOME>>/etc/zope.conf')
>>   startup()
>>   # mod_wsgi looks for the special name 'application'.
>>   from ZPublisher.WSGIPublisher import publish_module as application
>>
>> which works, mostly, except that all the App.ImageFile stuff, as well as
>> anything else using IStreamIterator, doesn't.  Streaming output also
>> doesn't work:  I'm not sure what else.
> 
> That's pretty cool. :)
> 
> I think people will be a bit confused about the relationship between 
> this and repoze.zope2, though. Maybe we can make a statement about how 
> they differ and whether they ought to be consolidated?

repoze.zope2 was written to get pre-eggified, pre-WSGI-aware Zope
(<=2.11.x) deployable using eggs and Paste.  2.12 is eggified, and
speaks a kind of pidgin WSGI;  repoze.zope2 is likely still useful,
becuase it is more "fluent" in WSGI.  See below for futures.

> As for IStreamIterator, I think it should work to just return the 
> iterator as the WSGI body iterator. At least that works in repoze.zope2.
> 
>> I set out to fix these bugs in ZPublisher.WSGIPublisher.WSGIResponse,
>> and was dismayed to find it an untested hack-up of the original Publish
>> module, with an untested subclass of HTTPResponse, itself almost
>> completely test-free.  So I went down the rabbit hole, and got nearly
>> 100% coverage of HTTPResponse on my branch, along with cleaning out some
>> decade-old fossils.
> 
> That's really awesome!
> 
>> Remaining work would be to write tests for WSGIResponse, and then tweak
>> it (and HTTPResponse) to make doing the Right Thing(TM) possible for
>> responses which are more than just a single big string.
> 
> Are there any cases other than IStreamIteartor in that case?

response.write() is the other one I know about.  Getting it to do the
Right Thing(TM) under WSGI is going to be tricky, I think.

>> Beyond fixing those bugs:
>>
>> - - Document using Zope2 behind mod_wsgi.
>>
>> - - Write a function usable as a PasteDeploy app factory, to allow
>>    configuration of Zope2 as the endpoint of a pipeline.  Document
>>    this feature.
>>
>> - - Supply a stripped-down version of WSGIPublisher, delgating the
>>    current implementation's "full stack" behavior (error handling,
>>    transaction / retry integration) to middleware.  The guts of this
>>    can be lifted from repoze.zope2.z2bob. Document using this lighter-
>>    weight publisher.

If it gets that far by Zope 2.13, then we can likely retire repoze.zope2.


Trs.
- --
===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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