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 Refresh. 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 Refresh. 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 GetRefreshPaths(self): 23 '''Returns a list of paths to query 24 (relative to _refresh/<data_source_name>/) with the task queue in order 25 to refresh this DataSource's data set. Any paths listed here will be 26 routed to the DataSource Refresh method in a taskqueue task request. 27 ''' 28 return [''] 29 30 def Refresh(self, path=None): 31 '''Handles _refresh requests to this DataSource. Should return a Future 32 indicating the success or failure of the refresh.''' 33 raise NotImplementedError(self.__class__) 34 35 def get(self, key): 36 '''Returns a dictionary or list that can be consumed by a template. Called 37 on an offline file system and can only access files in the cache. 38 ''' 39 raise NotImplementedError(self.__class__) 40
