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#!/usr/bin/env python
'''
Simple dispatcher for the REST API.
Only intended for test purposes.
License
-------
===================================================================
Copyright (c) 2017 AT&T Intellectual Property. All rights reserved.
===================================================================
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
'''
import logging
logger = logging.getLogger('collector.disp')
base_url = ''
template_404 = b'''POST {0}'''
def set_404_content(url):
'''
Called at initialization to set the base URL so that we can serve helpful
diagnostics as part of the 404 response.
'''
global base_url
base_url = url
return
def notfound_404(environ, start_response):
'''
Serve the 404 Not Found response.
Provides diagnostics in the 404 response showing the hierarchy of valid
REST resources.
'''
logger.warning('Unexpected URL/Method: {0} {1}'.format(
environ['REQUEST_METHOD'].upper(),
environ['PATH_INFO']))
start_response('404 Not Found', [ ('Content-type', 'text/plain') ])
return [template_404.format(base_url)]
class PathDispatcher:
'''
A dispatcher which can take HTTP requests in a WSGI environment and invoke
appropriate methods for each request.
'''
def __init__(self):
'''Constructor: initialize the pathmap to be empty.'''
self.pathmap = { }
def __call__(self, environ, start_response):
'''
The main callable that the WSGI app will invoke with each request.
'''
#----------------------------------------------------------------------
# Extract the method and path from the environment.
#----------------------------------------------------------------------
method = environ['REQUEST_METHOD'].lower()
path = environ['PATH_INFO']
logger.info('Dispatcher called for: {0} {1}'.format(method, path))
logger.debug('Dispatcher environment is: {0}'.format(environ))
#----------------------------------------------------------------------
# See if we have a handler for this path, and if so invoke it.
# Otherwise, return a 404.
#----------------------------------------------------------------------
handler = self.pathmap.get((method, path), notfound_404)
logger.debug('Dispatcher will use handler: {0}'.format(handler))
return handler(environ, start_response)
def register(self, method, path, function):
'''
Register a handler for a method/path, adding it to the pathmap.
'''
logger.debug('Registering for {0} at {1}'.format(method, path))
print('Registering for {0} at {1}'.format(method, path))
self.pathmap[method.lower(), path] = function
return function
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