WSGI Dispatcher

Overview

The WSGI Dispatcher middleware does three things:

1. It checks environ['wsgiorg.routing_args'] and invokes a WSGI application from a list of predefined directories if there is a match or a returns an HTTP 404.
2. It checks environ['PATH_INFO'] for one or more predefined URLs and serves static content from corresponding directories.
3. It checks environ['PATH_INFO'] for one or more predefined URLs and invokes WSGI applications (which may well be other dispatchers).

The dispatcher is intented to work behind WSGI URL parsers like Routes which parse request URLs and place named or positional arguments in environ['wsgiorg.routing_args'].

Download

WSGIDispatcher-0.3.tar.gz (Development Status :: 4 - Beta)

WSGIDispatcher-0.2.tar.gz (Development Status :: 4 - Beta)

WSGIDispatcher-0.1.tar.gz (Development Status :: 3 - Alpha)

Detailed Description

Constructor Arguments

The WSGI Dispatcher constructor accepts the following arguments:

• controller_dirs A list of directories containing WSGI applications (or controllers in an MVC context).
• match_named (default: True) environ['wsgiorg.routing_args'] is a two-tuple of (positional_args, named_args). If match_named is set to True, the dispatcher uses named_args to dispatch, if set to False it uses positional_args.
• with_action (default: False) If set to True the dispatcher will try to locate the WSGI application and invoke one of its methods (also referred to as "action"). For example, using Routes, one may specify m.connect('home', '', controller='blog', action='index'), in which case the dispatcher will try to instantiate the "blog" class (the name may differ according to transformation rules which will be discussed later) and call its "index" method like a WSGI application, passing it environ and start_response.
• not_found_app (default: None) Pass a WSGI application to be called when no match is found. By default the dispatcher returns an HTTP 404.

Additional Functionality

Furthermore, the functionality of the dispatcher can be customised setting the following WSGI Dispatcher properties:

• fname_pattern (default: None) Use the fname_pattern to find WSGI application/controllers in controller_dirs. For example, for d.fname_pattern = "Taste%(filename)sPotatoes" the dispatcher will match: "Taste<controller name in environ[wsgiorg.routingargs']>Potatoes.py"; assuming the controller name was "index", the dispatcher would load the filename: "TasteindexPotatoes.py".
• fname_transform_func (default: None) Use the fname_transform_func to transform the controller filename before trying to find WSGI application/controllers in controller_dirs. For example, for d.fname_transform_func = lambda x: x[0].upper() + x[1:], for a controller filename "index", and the previous fname_pattern value, the dispatcher would load the filename: "TasteIndexPotatoes.py".
• classname_pattern (default: None) Use the classname_pattern to find the classname of the WSGI application/controller. For example, for d.classname_pattern = "Tasty%(classname)sPotato" the dispather will match: "Tasty<controller name in environ[wsgiorg.routingargs']>Potato"; assuming the controller name was "index", the dispatcher will use the class "TastyindexPotato."
• classname_transform_func (default: None) Same functionality as fname_transform_func but for class names.
• action_pattern (default: None) Same functionality as classname_pattern; use %(action)s for the action name placeholder.
• action_transform_func (default: None) Same functionality as fname_transform_func and classname_transform_func but for action names.

Serving Static Resources and Secondary Dispatching

Furthermore, the dispatcher uses Paste's URLMap to serve static content and/or to call other WSGI applications based on specific URLs.

• add_static_dir(url, dir_path) Serves static resources from directory dir_path when url is matched in environ['PATH_INFO'].
• add_app_dispatcher(url, dir_path) Invokes a WSGI application from dir_path when url is matched in environ['PATH_INFO'].

For more information on the syntax of URLs (url) and the matching behaviour please refer to URLMap documentation.

Examples

      from paste.pony import PonyMiddleware
      from routes.middleware import Mapper, RoutesMiddleware
      # Mapper needed for Routes.
      from config.routing import mapper
      from wsgi_dispatcher import WSGIDispatcher

      # Define the routes using Routes here.
      mapper = Mapper()
      mapper.connect('/webapp', controller="webapp")
      mapper.create_regs('webapp')

      dispatcher = WSGIDispatcher(controller_dirs = ["controllers"])
      dispatcher.classname_transform_func=lambda x: x[0].upper() + x[1:]
      dispatcher.add_static_dir('/test/', 'public/static')
      app = RoutesMiddleware(dispatcher, mapper)