[mod_python] Re: MySQLSession, wiki, development and other stuff

Graham Dumpleton grahamd at dscpl.com.au
Tue Nov 28 06:05:03 EST 2006

On 28/11/2006, at 10:04 AM, Martijn Moeling wrote:
> I emailed you guy's personally since you are the driving forces behind
> mod_python (i think) and this is not a real subject for that mailing
> list.

I see no reason why anything you talk about needs to be handled off
the mailing list, so have sent my response back there.

> I just send in a proposed new Session.py as a RFC backed with some
> documentation.
> I also found an today's article on the mailing list with subject:
> [mod_python] Wiki for mod_python. Contributors welcome.
> Which is about this subject, keeping the MySQLdb out as much as  
> possible
> was one of my goals, but I do not see another option.

There should be no reason for a MySQL session class to be within the
mod_python session code file for it to work. The only thing you don't  
get from
having it separate is the ability for it to be created underneath the  
call based on the value of PythonOption for setting the session type.
Instead you would use:

   req.session = MySqlSession(req)

The only place where having to do this would be a problem is if you are
using mod_python.psp as it internally uses Session.Session(). It only
does this though if req.session doesn't exist as an attribute. Thus,  
if you are
using mod_python.psp you need to create your own handler which does:

   from mod_python import psp

   def handler(req):
     req.session = MySqlSession(req)
     return psp.handler(req)

By assigning session instance to req.session, mod_python.psp will use  

You will need to have a recent version of mod_python for this to work

In mod_python 3.3, the ability to use the Apache authentication handler
phase properly means that creating sessions in the main content handler
phase is probably not as a good an option as writing a proper  
handler for the job. In that scenario, you wouldn't even need to wrap
mod_python.psp as session creation would be in a separate handler

> (yes I do: copy
> Session.py to my app dir and not include it from mod_python right?)

Making a copy of Session.py and modifying it is a bad idea as it is  
out of date if you are using mod_python 3.2.10 or older as various  
have been made in code in mod_python 3.3. You will loose the benefit of
these changes/fixes if you have your own copy based on an older version.

> Storing the Sessions in an SQL database can be a huge advantage and I
> think it should be in Session.py since it expands possibilities.  
> (think
> of the multiple front end severs in my situation, and there are File,
> DBM memory possibilities, so why not add MySQL (which is used by most
> mod_python users anyway). With my current project I am preparing for
> 1.000.000 pageviews per hour!! One apache server with mod_python  
> can not
> handle that amount of users. (not all use sessions)
> Personally I think mod_python and MySQLdb should team up, I am an
> experienced programmer, but all those newbie guys run into trouble
> configuring the lot

The topic of having SQL database backed sessions included as a standard
part of mod_python has been discussed before and rejected. Even the
sqlite version which I referred you to was rejected. The issue was  
that having
dependencies on external packages was not desirable as it makes the
development and testing more burdensome. This was even though sqlite  
doesn't require a big database system but can work direct out of the

If there is every to be database backed sessions included in  
mod_python as
a standard feature, I'd suggest it is more likely to be code which  
uses the
Apache 2.2 mod_dbd module in some way so that that stuff in Apache can
be leveraged for the task of database connection management etc. Keep in
mind that mod_python is all about trying to use what Apache provides as
much as possible, rather than creating a separate universe and just  
Apache as a hopping off point.

> I would love to contribute to the wiki, I'll see into it over the next
> few days. I have been a programmer devoted to Open Source since Linux
> was half a kernel (I implemented large parts of the V4 TCP/IP stack).

If you want to get involved in the wiki great. Adding the MySQLSession
class as an example would be a good thing to add to the wiki and for the
time being at least is probably the most appropriate place for it to go.

> Can you help me getting into mod_python development? I am  
> interested in
> adding useful features (like MySQLSession haha)

The way the Apache software foundation works is that new developers on
projects get commit access on the repository by way of invitation.  
They will
get an invitation by demonstrating good knowledge of the package by
helping out on the mailing lists by giving useful assistance to  
others. Finding
bugs in the package and investigating it to the level of being able  
to provide
a fix also helps. With the wiki now in place, contributing there  
would also
show your abilities and knowledge and in conjunction with other things
give confidence that providing you commit access to the source code  
be the right thing to do.

As a first step though, I would suggest you get yourself subscribed  
to the
mod_python developers mailing list in addition to the standard user  
list. I have never seen you post on the developers list so am  
assuming you
aren't subscribed there at present. Use the mailing list to learn,  
and contribute
as you can. If over time you give the core developers a good  
impression and
when we are looking for extra developers, then you would be considered.


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