4.7 Using mod_python to Deploy Applications

In all of the previous sections you will note that all of the programs used the Request class from the albatross.cgiapp module. The albatross.apacheapp module contains a Request class to allow you to deploy your application using mod_python 4.1. In this section we will modify the popview.py application to deploy it using mod_python.

In theory it is possible to change application deployment method from CGI to mod_python by changing less than 5 lines of code in the entire application. The complete sample program is contained in the samples/popview5 directory. Use the install.py script to install the sample.

cd samples/popview5
python install.py

The new popview.py mainline follows.

from albatross import ModularSessionApp, SessionAppContext
from albatross.apacheapp import Request
import popviewlib

class AppContext(SessionAppContext):

    def open_mbox(self):
        if hasattr(self.locals, 'mbox'):
            return
        self.locals.mbox = popviewlib.Mbox(self.locals.username, self.locals.passwd)

    def read_msg(self):
        if hasattr(self.locals, 'msg'):
            return
        self.locals.msg = self.locals.mbox[int(self.locals.msgnum) - 1]
        self.locals.msg.read_body()

class App(ModularSessionApp):

    def __init__(self):
        ModularSessionApp.__init__(self,
                                   base_url = 'popview.py',
                                   module_path = '-=-install_dir-=-',
                                   template_path = '-=-install_dir-=-',
                                   start_page = 'login',
                                   secret = '-=-secret-=-',
                                   session_appid = 'popview5')

    def create_context(self):
        return AppContext(self)

app = App()

def handler(req):
    return app.run(Request(req))

The handler() function is called by mod_python when a browser request is received that must be handled by the program.

You also need to create a .htaccess file to tell Apache to run the application using mod_python.

DirectoryIndex popview.py
SetHandler python-program
PythonHandler popview

Assuming you install the popview sample below the /var/www directory you will need configure Apache settings for the /var/www/alsamp directory:

<Directory /var/www/alsamp/>
    AllowOverride FileInfo Indexes
    Order allow,deny
    Allow from all
</Directory>



Footnotes

...mod_python 4.1
For more information on mod_python, including installation instructions, see http://www.modpython.org/.