[Web-SIG] using WSGI for standard pluggable applications

[Ian Bicking]

Ksenia Marasanova wrote:
> Sorry if this is a trivial question, but does it sounds reasonable to
> use WSGI for "pluggable" standard applications, instead of usual
> Python imports? For example, standard news module, like:
> 
> app = NewsApp(path='/site/news/')
> 
> The content of news app would be inserted into site template,
> generated by main publisher.    If there are any examples of such WSGI
> use, I'll be glad to hear that...

I think you are describing something along the lines of what Paste
Deploy is doing (http://pythonpaste.org/deploy/paste-deploy.html).

It uses Eggs with entry points (though plain imports are also allowed).
 So if you have a news application, you'd add this to its setup.py:

  setup(
      name="NewsApp", ...
      entry_points={
      'paste.app_factory': 'main=news.wsgiapp:make_app'})

news.wsgiapp looks like:

  def make_app(global_conf, database):
      # database is a required configuration variable specific to news
      # you return a plain WSGI application here


Then to deploy it, you create a configuration file (lets say site.ini):

  [composit:main]
  use = egg:Paste#urlmap
  /site/news = news
  /site/wiki = wiki
  / = static

  [app:news]
  use = egg:NewsApp
  database = sqlite:/path/to/db

  [app:wiki]
  use = egg:MoinMoin

  [app:static]
  use = egg:Paste#static
  document_root = /var/www



Then to use the configuration file you do:

  from paste.deploy import loadapp
  app = loadapp('config:/path/to/site.ini')
  # app is now a WSGI application that dispatches
  # based on URL to the three configured applications


Or you can do:

  paster serve site.ini

At least this will work if you define a server in the config file, like:

  [server:main]
  use = egg:PasteScript#wsgiutils
  port = 8000