1 # Copyright 2013 The Chromium Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 6 class DataSource(object): 7 ''' 8 Defines an abstraction for all DataSources. 9 10 DataSources must have two public methods, get and Cron. A DataSource is 11 initialized with a ServerInstance and a Request (defined in servlet.py). 12 Anything in the ServerInstance can be used by the DataSource. Request is None 13 when DataSources are created for Cron. 14 15 DataSources are used to provide templates with access to data. DataSources may 16 not access other DataSources and any logic or data that is useful to other 17 DataSources must be moved to a different class. 18 ''' 19 def __init__(self, server_instance, request): 20 pass 21 22 def Cron(self): 23 '''Must cache all files needed by |get| to persist them. Called on a live 24 file system and can access files not in cache. |request| will be None. 25 ''' 26 raise NotImplementedError(self.__class__) 27 28 def get(self, key): 29 '''Returns a dictionary or list that can be consumed by a template. Called 30 on an offline file system and can only access files in the cache. 31 ''' 32 raise NotImplementedError(self.__class__) 33
