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_factoryRouter __init__Router __call__Router _dispatchRouter match = {'action': u'getMessage', 'controller': <wsgi.Controller object at 0x17965d0>, 'user_id': u'123'}Controller __call__Controller action = getMessageController params = {}Controller method = <bound method Controller.getMessage of <wsgi.Controller object at 0x17965d0>>Controller getMessageController result = {'Message': 'TestMessage'}

WSGI server 创建文件：wsgi.py

import loggingimport osimport webob.decimport webob.excfrom paste.deploy import loadappfrom wsgiref.simple_server import make_serverimport 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'}        passclass 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