WSGI小程序

模拟openstack中的WSGI,先看一下运行过程中的调用顺序：

[root@jeguan-ctrl-01 WSGI]# python wsgi.py 
Router app_factory
Router __init__
Router __call__
Router _dispatch
Router match = {'action': u'getMessage', 'controller': <wsgi.Controller object at 0x17965d0>, 'user_id': u'123'}
Controller __call__
Controller action = getMessage
Controller params = {}
Controller method = <bound method Controller.getMessage of <wsgi.Controller object at 0x17965d0>>
Controller getMessage
Controller result = {'Message': 'TestMessage'}

WSGI server 创建文件：wsgi.py

import logging
import os

import webob.dec
import webob.exc
from paste.deploy import loadapp
from wsgiref.simple_server import make_server

import routes.middleware
# Environment variable used to pass the request context  
CONTEXT_ENV = 'openstack.context'

# Environment variable used to pass the request params  
PARAMS_ENV = 'openstack.params'

LOG = logging.getLogger(__name__)

class Controller(object):
    @webob.dec.wsgify
    def __call__(self, req):
        print "Controller __call__"
        arg_dict = req.environ['wsgiorg.routing_args'][1]
        action = arg_dict.pop('action')
        print "Controller action = %s" % action
        del arg_dict['controller']
        context = req.environ.get(CONTEXT_ENV, {})
        context['query_string'] = dict(req.params.iteritems())
        context['headers'] = dict(req.headers.iteritems())
        context['path'] = req.environ['PATH_INFO']
        params = req.environ.get(PARAMS_ENV, {})
        print "Controller params = %s" % params

        for name in ['REMOTE_USER', 'AUTH_TYPE']:
            try:
                context[name] = req.environ[name]
            except KeyError:
                try:
                    del context[name]
                except KeyError:
                    pass

        params.update(arg_dict)

        # TODO(termie): do some basic normalization on methods  
        method = getattr(self, action)
        print "Controller method = %s" % method

        result = method(context, **params)
        print "Controller result = %s" % result

        return webob.Response('OK')

    def getMessage(self,context, user_id):
        print "Controller getMessage"
        return {'Message': 'TestMessage'}
        pass

class Router(object):
    def __init__(self):
        print "Router __init__"
        self._mapper = routes.Mapper()
        self._mapper.connect('/test/{user_id}',
                            controller=Controller(),
                            action='getMessage',
                            conditions={'method': ['GET']})

        self._router = routes.middleware.RoutesMiddleware(self._dispatch, self._mapper)

    @webob.dec.wsgify
    def __call__(self, req):
        print "Router __call__"
        return self._router

    @staticmethod
    @webob.dec.wsgify
    def _dispatch(req):
        print "Router _dispatch"
        match = req.environ['wsgiorg.routing_args'][1]
        print "Router match = %s" % match

        if not match:
            return webob.exc.HTTPNotFound()

        app = match['controller']
        return app

    @classmethod
    def app_factory(cls, global_config, **local_config):
        print "Router app_factory"
        return cls()


if __name__ == '__main__':

    """
    Openstack WSGI interface:
    create a "Controller" and "Router" class with webob,pastedeploy,routes.
    Test case for Openstack WSGI.
    """
    configfile='testpaste.ini'
    appname="main"
    wsgi_app = loadapp("config:%s" % os.path.abspath(configfile), appname)

paste deploy文件：testpaste.ini

[DEFAULT]
name=guan

[composite:main]
use=egg:Paste#urlmap
/=show

[pipeline:show]
pipeline = root

[app:root]
paste.app_factory = wsgi:Router.app_factory

程序入口：

从testpaste.init可以看出，程序的入口处：

 wsgi:Router.app_factory