Source Code for Module brisa.upnp.base_service_builder

  1  # Licensed under the MIT license 
  2  # http://opensource.org/licenses/mit-license.php 
  3  # Copyright 2007-2008 Brisa Team <brisa-develop@garage.maemo.org> 
  4   
  5  """ Builder module for services. 
  6  """ 
  7   
  8  from xml.etree import cElementTree as ElementTree 
  9   
 10  from brisa.core import log 
 11   
 12  from brisa.upnp.base_action import BaseArgument, BaseAction 
 13  from brisa.upnp.base_service import BaseStateVariable 
 14   
 15   
 16 -class BaseServiceBuilder(object): 
 17   
 18 -    def __init__(self, service, fd): 
 19          self.service = service 
 20          self.fd = fd 
 21          self._actions = {} 
 22          self._variables = {} 
 23   
 24 -    def build(self): 
 25          """ Builds a service given a file descriptor containing the SCPD XML. 
 26   
 27          @return: True if service build succeeded, otherwise False. 
 28          @rtype: bool 
 29          """ 
 30          if not self._parse_description(self.fd): 
 31              return False 
 32          self._build_service() 
 33          return True 
 34   
 35 -    def _parse_description(self, fd): 
 36          """ Parses the actions and state variables of a service given a file 
 37          descriptor containing the SCPD XML. File descriptor must be open. 
 38   
 39          @param fd: file descriptor 
 40          @type fd: file 
 41   
 42          @return: True if service parser succeeded, otherwise False. 
 43          @rtype: bool 
 44          """ 
 45          try: 
 46              data = fd.read() 
 47              data = data[data.find("<"):data.rfind(">")+1] 
 48              tree = ElementTree.XML(data) 
 49              if tree: 
 50                  self._parse_actions(tree) 
 51                  self._parse_variables(tree) 
 52                  return True 
 53          except Exception, e: 
 54              log.debug('Could not build service SCPD XML. %s' % str(e)) 
 55   
 56          return False 
 57   
 58 -    def _parse_actions(self, tree): 
 59          """ Parses actions from a fetched tree. 
 60   
 61          @param tree: tree containing the actions 
 62          @type tree: ElementTree 
 63          """ 
 64          ns = "urn:schemas-upnp-org:service-1-0" 
 65          for node in tree.findall('.//{%s}action' % ns): 
 66              name = node.findtext('{%s}name' % ns) 
 67              args = [] 
 68              for arg in node.findall('.//{%s}argument' % ns): 
 69                  arg_direction = arg.findtext('{%s}direction' % ns) 
 70                  arg_state_var = arg.findtext('{%s}relatedStateVariable' % ns) 
 71                  arg_name = arg.findtext('{%s}name' % ns) 
 72                  args.append((arg_name, arg_direction, arg_state_var)) 
 73              self._actions[name] = args 
 74   
 75 -    def _parse_variables(self, tree): 
 76          """ Parses variables from a fetched tree. 
 77   
 78          @param tree: tree containing the actions 
 79          @type tree: ElementTree 
 80          """ 
 81          ns = "urn:schemas-upnp-org:service-1-0" 
 82          for node in tree.findall('.//{%s}stateVariable' % ns): 
 83              # Avoid breaking when sendEvents is not specified. 
 84              send_events = node.attrib.get('sendEvents', 'no') 
 85              # Avoid breaking when multicast is not specified. 
 86              multicast = node.attrib.get('multicast', 'no') 
 87   
 88              name = node.findtext('{%s}name' % ns) 
 89              data_type = node.findtext('{%s}dataType' % ns) 
 90              values = [a.text for a in node.findall('.//{%s}allowedValue' % ns)] 
 91              self._variables[name] = (send_events, multicast, data_type, values) 
 92   
 93 -    def _build_service(self): 
 94          """ Builds a service. 
 95          """ 
 96          for name in self._variables.iterkeys(): 
 97              send_events, multicast, data_type, values = self._variables[name] 
 98              send_events = True if send_events == 'yes' else False 
 99              multicast = True if multicast == 'yes' else False 
100              self.service.add_state_variable(self.\ 
101                          _create_state_var(name, send_events, 
102                                         multicast, data_type, values)) 
103          for action_name, action_args in self._actions.iteritems(): 
104              args = [] 
105              for arg_name, arg_direction, arg_state_var in action_args: 
106                  args.append(self._create_argument(arg_name, 
107                      arg_direction, 
108                      self.service._state_variables[arg_state_var])) 
109              self.service._actions[action_name] = self.\ 
110                  _create_action(action_name, args) 
111   
112 -    def _create_argument(self, arg_name, arg_direction, arg_state_var): 
113          """ Factory method that creates an action argument. 
114   
115          @return: The argument object. 
116          @rtype: BaseArgument 
117          """ 
118          return BaseArgument(arg_name, arg_direction, arg_state_var) 
119   
120 -    def _create_action(self, name, args): 
121          """ Factory method that creates a service action. 
122   
123          @return: The action object. 
124          @rtype: BaseAction 
125          """ 
126          return BaseAction(self.service, name, args) 
127   
128 -    def _create_state_var(self, name, send_events, multicast, 
129                            data_type, values): 
130          """ Factory method that creates a service state variable. 
131   
132          @return: The state variable object. 
133          @rtype: BaseStateVariable 
134          """ 
135          return BaseStateVariable(self.service, 
136                      name, send_events, multicast, data_type, values) 
137