add websocket workarounds for tornado 3

WebSocketHandler.get is new in tornado 4

IPython/html/base/zmqhandlers.py

@@ -1,3 +1,4 b''
+# coding: utf-8
 """Tornado handlers for WebSocket <-> ZMQ sockets."""
 
 # Copyright (c) IPython Development Team.
@@ -11,12 +12,6 b' try:'
 except ImportError:
     from urlparse import urlparse # Py 2
 
-try:
-    from http.cookies import SimpleCookie  # Py 3
-except ImportError:
-    from Cookie import SimpleCookie  # Py 2
-import logging
-
 import tornado
 from tornado import ioloop
 from tornado import web
@@ -24,7 +19,7 b' from tornado import websocket'
 
 from IPython.kernel.zmq.session import Session
 from IPython.utils.jsonutil import date_default, extract_dates
-from IPython.utils.py3compat import PY3, cast_unicode
+from IPython.utils.py3compat import cast_unicode
 
 from .handlers import IPythonHandler
 
@@ -218,13 +213,21 b' class AuthenticatedZMQStreamHandler(ZMQStreamHandler, IPythonHandler):'
             self.session.session = cast_unicode(self.get_argument('session_id'))
         else:
             self.log.warn("No session ID specified")
-        
-        return super(AuthenticatedZMQStreamHandler, self).get(*args, **kwargs)
+        # FIXME: only do super get on tornado ≥ 4
+        # tornado 3 has no get, will raise 405
+        if tornado.version_info >= (4,):
+            return super(AuthenticatedZMQStreamHandler, self).get(*args, **kwargs)
     
     def initialize(self):
         self.session = Session(config=self.config)
     
     def open(self, *args, **kwargs):
+        if tornado.version_info < (4,):
+            try:
+                self.get(*self.open_args, **self.open_kwargs)
+            except web.HTTPError:
+                self.close()
+                raise
         
         # start the pinging
         if self.ping_interval > 0:

IPython/html/services/kernels/handlers.py

@@ -155,6 +155,7 b' class ZMQChannelHandler(AuthenticatedZMQStreamHandler):'
     def initialize(self):
         super(ZMQChannelHandler, self).initialize()
         self.zmq_stream = None
+        self.kernel_id = None
         self.kernel_info_channel = None
         self._kernel_info_future = Future()
     
@@ -168,7 +169,8 b' class ZMQChannelHandler(AuthenticatedZMQStreamHandler):'
         super(ZMQChannelHandler, self).open()
         try:
             self.create_stream()
-        except web.HTTPError:
+        except web.HTTPError as e:
+            self.log.error("Error opening stream: %s", e)
             # WebSockets don't response to traditional error codes so we
             # close the connection.
             if not self.stream.closed():