src/python/osrf/gateway.py

   1 from xml.dom import minidom
   2 from xml.sax import handler, make_parser, saxutils
   3 from json import *
   4 from net_obj import *
   5 import urllib, urllib2, sys, re
   6
   7 defaultHost = None
   8 #paramRegex = re.compile('\%27')
   9
  10 class GatewayRequest:
  11     def __init__(self, service, method, params=[]):
  12         self.service = service
  13         self.method = method
  14         self.params = params
  15
  16     def send(self):
  17         params = self.buildPOSTParams()
  18         request = urllib2.Request(self.buildURL(), data=params)
  19         response = None
  20         try:
  21             response =urllib2.urlopen(request)
  22         except urllib2.HTTPError, e:
  23             # log this?
  24             sys.stderr.write('%s => %s?%s\n' % (str(e), self.buildURL(), params))
  25             raise e
  26
  27         return self.handleResponse(response)
  28
  29     def buildPOSTParams(self):
  30
  31         params = urllib.urlencode({
  32             'service': self.service,
  33             'method': self.method,
  34             'format': self.getFormat(),
  35             'input_format': self.getInputFormat()
  36         })
  37
  38         for p in self.params:
  39             params += '&param=%s' % urllib.quote(self.encodeParam(p), "'/")
  40         return params
  41
  42     def setDefaultHost(host):
  43         global defaultHost
  44         defaultHost = host
  45     setDefaultHost = staticmethod(setDefaultHost)
  46
  47     def buildURL(self):
  48         return 'http://%s/gateway' % defaultHost
  49
  50
  51 class XMLGatewayRequest(GatewayRequest):
  52
  53     def __init__(self, service, method, *params):
  54         GatewayRequest.__init__(self, service, method, list(params))
  55
  56     def getFormat(self):
  57         return 'xml'
  58
  59     def getInputFormat(self):
  60         return self.getFormat()
  61
  62     def handleResponse(self, response):
  63         handler = XMLGatewayParser()
  64         parser = make_parser()
  65         parser.setContentHandler(handler)
  66         parser.parse(response)
  67         return handler.getResult()
  68
  69     def encodeParam(self, param):
  70         return osrfObjectToXML(param);
  71
  72 class XMLGatewayParser(handler.ContentHandler):
  73
  74     def __init__(self):
  75         self.result = None
  76         self.objStack = []
  77         self.keyStack = []
  78         self.posStack = [] # for tracking array-based hinted object indices
  79
  80         # true if we are parsing an element that may have character data
  81         self.charsPending = 0
  82
  83     def getResult(self):
  84         return self.result
  85
  86     def __getAttr(self, attrs, name):
  87         for (k, v) in attrs.items():
  88             if k == name:
  89                 return v
  90         return None
  91
  92     def startElement(self, name, attrs):
  93
  94         if self.charsPending:
  95             # we just read a 'string' or 'number' element that resulted
  96             # in no text data.  Appaned a None object
  97             self.appendChild(None)
  98
  99         if name == 'null':
 100             self.appendChild(None)
 101             return
 102
 103         if name == 'string' or name == 'number':
 104             self.charsPending = True
 105             return
 106
 107         if name == 'element': # this is an object item wrapper
 108             self.keyStack.append(self.__getAttr(attrs, 'key'))
 109             return
 110
 111         hint = self.__getAttr(attrs, 'class_hint')
 112         if hint:
 113             obj = osrfNewObjectFromHint(hint)
 114             self.appendChild(obj)
 115             self.objStack.append(obj)
 116             if name == 'array':
 117                 self.posStack.append(0)
 118             return
 119
 120         if name == 'array':
 121             obj = []
 122             self.appendChild(obj)
 123             self.objStack.append(obj)
 124             return
 125
 126         if name == 'object':
 127             obj = {}
 128             self.appendChild(obj)
 129             self.objStack.append(obj)
 130             return
 131
 132         if name == 'boolean':
 133             self.appendChild((self.__getAttr(attrs, 'value') == 'true'))
 134             return
 135
 136
 137     def appendChild(self, child):
 138
 139         if self.result == None:
 140             self.result = child
 141
 142         if not self.objStack: return;
 143
 144         parent = self.objStack[len(self.objStack)-1]
 145
 146         if isinstance(parent, list):
 147             parent.append(child)
 148         else:
 149             if isinstance(parent, dict):
 150                 parent[self.keyStack.pop()] = child
 151             else:
 152                 if isinstance(parent, osrfNetworkObject):
 153                     key = None
 154                     if parent.getRegistry().wireProtocol == 'array':
 155                         keys = parent.getRegistry().keys
 156                         i = self.posStack.pop()
 157                         key = keys[i]
 158                         if i+1 < len(keys):
 159                             self.posStack.append(i+1)
 160                     else:
 161                         key = self.keyStack.pop()
 162
 163                     parent.setField(key, child)
 164
 165     def endElement(self, name):
 166         if name == 'array' or name == 'object':
 167             self.objStack.pop()
 168
 169     def characters(self, chars):
 170         self.charsPending = False
 171         self.appendChild(urllib.unquote_plus(chars))
 172
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