Allow decoding buffers in comm message (#108)

* Allow decoding buffers in comm message

* Fix decoding

pyviz_comms/__init__.py

@@ -295,40 +295,34 @@ def __init__(self, id=None, on_msg=None, on_error=None, on_stdout=None, on_open=
         self._comm = None
         super(Comm, self).__init__(id = id if id else uuid.uuid4().hex)
 
-
     def init(self, on_msg=None):
         """
         Initializes comms channel.
         """
 
-
     def close(self):
         """
         Closes the comm connection
         """
 
-
     def send(self, data=None, metadata=None, buffers=[]):
         """
         Sends data to the frontend
         """
 
-
     @classmethod
     def decode(cls, msg):
         """
         Decode incoming message, e.g. by parsing json.
         """
         return msg
 
-
     @property
     def comm(self):
         if not self._comm:
             raise ValueError('Comm has not been initialized')
         return self._comm
 
-
     def _handle_msg(self, msg):
         """
         Decode received message before passing it to on_msg callback
@@ -413,7 +407,6 @@ def init(self):
         if self._on_open:
             self._on_open({})
 
-
     @classmethod
     def decode(cls, msg):
         """
@@ -422,15 +415,13 @@ def decode(cls, msg):
         """
         return msg['content']['data']
 
-
     def close(self):
         """
         Closes the comm connection
         """
         if self._comm:
             self._comm.close()
 
-
     def send(self, data=None, metadata=None, buffers=[]):
         """
         Pushes data across comm socket.
@@ -440,7 +431,6 @@ def send(self, data=None, metadata=None, buffers=[]):
         self.comm.send(data, metadata=metadata, buffers=buffers)
 
 
-
 class JupyterCommJS(JupyterComm):
     """
     JupyterCommJS provides a comms channel for the Jupyter notebook,
@@ -460,6 +450,13 @@ class JupyterCommJS(JupyterComm):
     </script>
     """
 
+    @classmethod
+    def decode(cls, msg):
+        decoded = dict(msg['content']['data'])
+        if 'buffers' in msg:
+            decoded['_buffers'] = {i: v for i, v in enumerate(msg['buffers'])}
+        return decoded
+
     def __init__(self, id=None, on_msg=None, on_error=None, on_stdout=None, on_open=None):
         """
         Initializes a Comms object