osm_ro/http_tools/handler.py

   1 # -*- coding: utf-8 -*-
   2 ##
   3 # Copyright 2018 University of Bristol - High Performance Networks Research
   4 # Group
   5 # All Rights Reserved.
   6 #
   7 # Contributors: Anderson Bravalheri, Dimitrios Gkounis, Abubakar Siddique
   8 # Muqaddas, Navdeep Uniyal, Reza Nejabati and Dimitra Simeonidou
   9 #
  10 # Licensed under the Apache License, Version 2.0 (the "License"); you may
  11 # not use this file except in compliance with the License. You may obtain
  12 # a copy of the License at
  13 #
  14 #         http://www.apache.org/licenses/LICENSE-2.0
  15 #
  16 # Unless required by applicable law or agreed to in writing, software
  17 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  18 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  19 # License for the specific language governing permissions and limitations
  20 # under the License.
  21 #
  22 # For those usages not covered by the Apache License, Version 2.0 please
  23 # contact with: <highperformance-networks@bristol.ac.uk>
  24 #
  25 # Neither the name of the University of Bristol nor the names of its
  26 # contributors may be used to endorse or promote products derived from
  27 # this software without specific prior written permission.
  28 #
  29 # This work has been performed in the context of DCMS UK 5G Testbeds
  30 # & Trials Programme and in the framework of the Metro-Haul project -
  31 # funded by the European Commission under Grant number 761727 through the
  32 # Horizon 2020 and 5G-PPP programmes.
  33 ##
  34
  35 from types import MethodType
  36
  37 from bottle import Bottle
  38
  39
  40 class route(object):
  41     """Decorator that stores route information, so creating the routes can be
  42     postponed.
  43
  44     This allows methods (OOP) with bottle.
  45
  46     Arguments:
  47         method: HTTP verb (e.g. ``'get'``, ``'post'``, ``'put'``, ...)
  48         path: URL path that will be handled by the callback
  49     """
  50     def __init__(self, method, path, **kwargs):
  51         kwargs['method'] = method.upper()
  52         self.route_info = (path, kwargs)
  53
  54     def __call__(self, function):
  55         function.route_info = self.route_info
  56         return function
  57
  58
  59 class BaseHandler(object):
  60     """Base class that allows isolated webapp implementation using Bottle,
  61     when used in conjunction with the ``route`` decorator.
  62
  63     In this context, a ``Handler`` is meant to be a collection of Bottle
  64     routes/callbacks related to a specific topic.
  65
  66     A ``Handler`` instance can produce a WSGI app that can be mounted or merged
  67     inside another more general bottle app.
  68
  69     Example:
  70
  71         from http_tools.handler import Handler, route
  72         from http_tools.errors import ErrorHandler
  73
  74         class MyHandler(Handler):
  75             plugins = [ErrorHandler()]
  76             url_base = '/my/url/base'
  77
  78             @route('GET', '/some/path/<var>')
  79             def get_var(self, var):
  80                 return var
  81
  82         app = MyHandler.wsgi_app
  83         # ^  Webapp with a `GET /my/url/base/some/path/<var>` route
  84     """
  85     _wsgi_app = None
  86
  87     url_base = ''
  88     """String representing a path fragment to be prepended to the routes"""
  89
  90     plugins = []
  91     """Bottle plugins to be installed when creating the WSGI app"""
  92
  93     @property
  94     def wsgi_app(self):
  95         """Create a WSGI app based on the implemented callbacks"""
  96
  97         if self._wsgi_app:
  98             # Return if cached
  99             return self._wsgi_app
 100
 101         app = Bottle()
 102
 103         members = (getattr(self, m) for m in dir(self) if m != 'wsgi_app')
 104         callbacks = (m for m in members
 105                      if isinstance(m, MethodType) and hasattr(m, 'route_info'))
 106
 107         for callback in callbacks:
 108             path, kwargs = callback.route_info
 109             kwargs.update(callback=callback, apply=self.plugins)
 110             app.route(self.url_base + path, **kwargs)
 111
 112         self._wsgi_app = app
 113
 114         return app