[mod_python] mod_python and mod_dav

Graham Dumpleton grahamd at dscpl.com.au
Sat Feb 25 05:16:12 EST 2006

On 25/02/2006, at 8:55 PM, Troy Kruthoff wrote:

> I'm trying to figure out the best way to add webdav capability to a
> mod_python web app.   In short, I want to send/update calendar files
> via calendar information stored in a database.  I've googled for
> python based webdav server modules, and found 2, but the newest one
> was last updated in 2000.
> My first thought was to write something in C that allowed mod_python
> to control mod_dav, but this looks tricky and looks like it will take
> me too long and crush my ego by confirming that I suck at C.
> Second thought is to dig up the wevdav RFC and make a webdav server
> module that will work as a mod_python handler (or at least called from
> one).
> Third thought is to use a fixup handler.  This is where I'd really
> like some feedback!  Can I (in a fixup) ascertain that the content
> handler will be mod_dav, query the database, and write the requested
> file to disk just before mod_dav is asked to push it to the client?

I have a idea of how mod_dav_python could be constructed. I had put
the idea on the back burner for the moment. Here is email where I have
posted a little bit about my ideas before when someone raised the idea
of mod_dav/mod_python integration.

See below:

> On 30/01/2006, at 9:49 PM, Matt Carpenter wrote:
>> Graham Dumpleton wrote:
>>> Others may know what you are talking about, but I plead ignorance.
>>> Can
>>> you perhaps describe further what you are talking about, how it
>>> would be
>>> used etc. A URL to stuff that could be read to understand similar
>>> things
>>> would also help.
>>> Graham
>> What I am trying to achieve:
>> I'm writing a module for our system for managing documents that're
>> attached to records in our database, updates to these documents are
>> recorded into the database along with what user made the user that
>> made the edit, and various other information depending on what type
>> of document (the system manages templates, and mailmerges with
>> virtual .csv files pulling data from the database as well). The
>> directory structure is entirely virtual, the structure on the
>> servers is just a few directories for each type of file, and the
>> files are named after their record in the database.
>> mod_dav implements hooks (see http://mailman.lyra.org/pipermail/dav-
>> dev/2005-April/005926.html), but I'm not a C programmer, so I'd
>> like a these hooks to be able to call python functions instead.
>> Hope that makes sense.
> Regardless of how you might use it, from a technical standpoint I
> would say that it is not going to be possible at present.
> One could imagine being able to write a separate C based Apache    
> module
> which provides Python based wrappings for the DAV specific data
> structures   that the repository hook function use. As documented in:
>    http://docx.webperf.org/structdav__hooks__repository.html
> But, there are a few things missing. First, is there is no way to
> obtain references to the Python interpreter instances held by
> mod_python, the mechanisms for creating them and acquiring locks  
> against
> them from a distinct Apache   module. Similarly, there is there is no
> way to access the mod_python Python   request_rec wrapper object etc.
> Both of these and possibly other stuff would be required. You do not
> want to go having to duplicate all this stuff as it sort of defeats  
> the
> purpose   and would possibly prevent use of mod_python and your module
> in the same Apache instance.
> What would be an interesting area for investigation in the future
> would be to work out whether there are functions within the mod_python
> module   which could be exposed using the Apache
> APR_RETRIEVE_OPTIONAL_FN() interface. This would allow distinct  
> modules
> to dynamically obtain references to   some of the internals of
> mod_python so as to perhaps make use of all the   machinery it has
> already for manipulating Python interpreters, as well as   existing
> Python object wrappers for Apache structures.
> The end result would be the ability to create distinct C based Apache
> modules which themselves can also make use of Python by  
> bootstrapping of
> mod_python. It may be tricky to work out how to do it and come up  
> with a
> good   interface design, but certainly would be interesting.
> Graham

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