use pyzmq tools where appropriate

ZMQStream is the right object to use for event-driven handling of messages, but instead we chose to rewrite half of it in KernelManager.

This removes most of the duplicate code, in favor of using ZMQStream.

also use the pyzmq install() function for using pyzmq with tornado, instead of manually pasting its contents in notebook app.

IPython/frontend/html/notebook/notebookapp.py

@@ -1,333 +1,332 b''
 """A tornado based IPython notebook server.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # stdlib
 import errno
 import logging
 import os
 import signal
 import socket
 import sys
 import threading
 import webbrowser
 
 # Third party
 import zmq
 
 # Install the pyzmq ioloop. This has to be done before anything else from
 # tornado is imported.
 from zmq.eventloop import ioloop
-import tornado.ioloop
-tornado.ioloop.IOLoop = ioloop.IOLoop
+ioloop.install()
 
 from tornado import httpserver
 from tornado import web
 
 # Our own libraries
 from .kernelmanager import MappingKernelManager
 from .handlers import (LoginHandler, LogoutHandler,
     ProjectDashboardHandler, NewHandler, NamedNotebookHandler,
     MainKernelHandler, KernelHandler, KernelActionHandler, IOPubHandler,
     ShellHandler, NotebookRootHandler, NotebookHandler, RSTHandler
 )
 from .notebookmanager import NotebookManager
 
 from IPython.config.application import catch_config_error
 from IPython.core.application import BaseIPythonApplication
 from IPython.core.profiledir import ProfileDir
 from IPython.zmq.session import Session, default_secure
 from IPython.zmq.zmqshell import ZMQInteractiveShell
 from IPython.zmq.ipkernel import (
     flags as ipkernel_flags,
     aliases as ipkernel_aliases,
     IPKernelApp
 )
 from IPython.utils.traitlets import Dict, Unicode, Integer, List, Enum, Bool
 
 #-----------------------------------------------------------------------------
 # Module globals
 #-----------------------------------------------------------------------------
 
 _kernel_id_regex = r"(?P<kernel_id>\w+-\w+-\w+-\w+-\w+)"
 _kernel_action_regex = r"(?P<action>restart|interrupt)"
 _notebook_id_regex = r"(?P<notebook_id>\w+-\w+-\w+-\w+-\w+)"
 
 LOCALHOST = '127.0.0.1'
 
 _examples = """
 ipython notebook                       # start the notebook
 ipython notebook --profile=sympy       # use the sympy profile
 ipython notebook --pylab=inline        # pylab in inline plotting mode
 ipython notebook --certfile=mycert.pem # use SSL/TLS certificate
 ipython notebook --port=5555 --ip=*    # Listen on port 5555, all interfaces
 """
 
 #-----------------------------------------------------------------------------
 # The Tornado web application
 #-----------------------------------------------------------------------------
 
 class NotebookWebApplication(web.Application):
 
     def __init__(self, ipython_app, kernel_manager, notebook_manager, log):
         handlers = [
             (r"/", ProjectDashboardHandler),
             (r"/login", LoginHandler),
             (r"/logout", LogoutHandler),
             (r"/new", NewHandler),
             (r"/%s" % _notebook_id_regex, NamedNotebookHandler),
             (r"/kernels", MainKernelHandler),
             (r"/kernels/%s" % _kernel_id_regex, KernelHandler),
             (r"/kernels/%s/%s" % (_kernel_id_regex, _kernel_action_regex), KernelActionHandler),
             (r"/kernels/%s/iopub" % _kernel_id_regex, IOPubHandler),
             (r"/kernels/%s/shell" % _kernel_id_regex, ShellHandler),
             (r"/notebooks", NotebookRootHandler),
             (r"/notebooks/%s" % _notebook_id_regex, NotebookHandler),
             (r"/rstservice/render", RSTHandler)
         ]
         settings = dict(
             template_path=os.path.join(os.path.dirname(__file__), "templates"),
             static_path=os.path.join(os.path.dirname(__file__), "static"),
             cookie_secret=os.urandom(1024),
             login_url="/login",
         )
         web.Application.__init__(self, handlers, **settings)
 
         self.kernel_manager = kernel_manager
         self.log = log
         self.notebook_manager = notebook_manager
         self.ipython_app = ipython_app
         self.read_only = self.ipython_app.read_only
 
 
 #-----------------------------------------------------------------------------
 # Aliases and Flags
 #-----------------------------------------------------------------------------
 
 flags = dict(ipkernel_flags)
 flags['no-browser']=(
     {'NotebookApp' : {'open_browser' : False}},
     "Don't open the notebook in a browser after startup."
 )
 flags['read-only'] = (
     {'NotebookApp' : {'read_only' : True}},
     """Allow read-only access to notebooks.
     
     When using a password to protect the notebook server, this flag
     allows unauthenticated clients to view the notebook list, and
     individual notebooks, but not edit them, start kernels, or run
     code.
     
     If no password is set, the server will be entirely read-only.
     """
 )
 
 # the flags that are specific to the frontend
 # these must be scrubbed before being passed to the kernel,
 # or it will raise an error on unrecognized flags
 notebook_flags = ['no-browser', 'read-only']
 
 aliases = dict(ipkernel_aliases)
 
 aliases.update({
     'ip': 'NotebookApp.ip',
     'port': 'NotebookApp.port',
     'keyfile': 'NotebookApp.keyfile',
     'certfile': 'NotebookApp.certfile',
     'notebook-dir': 'NotebookManager.notebook_dir',
 })
 
 # remove ipkernel flags that are singletons, and don't make sense in
 # multi-kernel evironment:
 aliases.pop('f', None)
 
 notebook_aliases = [u'port', u'ip', u'keyfile', u'certfile',
                     u'notebook-dir']
 
 #-----------------------------------------------------------------------------
 # NotebookApp
 #-----------------------------------------------------------------------------
 
 class NotebookApp(BaseIPythonApplication):
 
     name = 'ipython-notebook'
     default_config_file_name='ipython_notebook_config.py'
     
     description = """
         The IPython HTML Notebook.
         
         This launches a Tornado based HTML Notebook Server that serves up an
         HTML5/Javascript Notebook client.
     """
     examples = _examples
     
     classes = [IPKernelApp, ZMQInteractiveShell, ProfileDir, Session,
                MappingKernelManager, NotebookManager]
     flags = Dict(flags)
     aliases = Dict(aliases)
 
     kernel_argv = List(Unicode)
 
     log_level = Enum((0,10,20,30,40,50,'DEBUG','INFO','WARN','ERROR','CRITICAL'),
                     default_value=logging.INFO,
                     config=True,
                     help="Set the log level by value or name.")
 
     # Network related information.
 
     ip = Unicode(LOCALHOST, config=True,
         help="The IP address the notebook server will listen on."
     )
 
     def _ip_changed(self, name, old, new):
         if new == u'*': self.ip = u''
 
     port = Integer(8888, config=True,
         help="The port the notebook server will listen on."
     )
 
     certfile = Unicode(u'', config=True, 
         help="""The full path to an SSL/TLS certificate file."""
     )
     
     keyfile = Unicode(u'', config=True, 
         help="""The full path to a private key file for usage with SSL/TLS."""
     )
 
     password = Unicode(u'', config=True,
                       help="""Hashed password to use for web authentication.
 
                       To generate, type in a python/IPython shell:
 
                         from IPython.lib import passwd; passwd()
 
                       The string should be of the form type:salt:hashed-password.
                       """
     )
     
     open_browser = Bool(True, config=True,
                         help="Whether to open in a browser after starting.")
     
     read_only = Bool(False, config=True,
         help="Whether to prevent editing/execution of notebooks."
     )
 
     def parse_command_line(self, argv=None):
         super(NotebookApp, self).parse_command_line(argv)
         if argv is None:
             argv = sys.argv[1:]
 
         self.kernel_argv = list(argv) # copy
         # Kernel should inherit default config file from frontend
         self.kernel_argv.append("--KernelApp.parent_appname='%s'"%self.name)
         # Scrub frontend-specific flags
         for a in argv:
             if a.startswith('-') and a.lstrip('-') in notebook_flags:
                 self.kernel_argv.remove(a)
         swallow_next = False
         for a in argv:
             if swallow_next:
                 self.kernel_argv.remove(a)
                 swallow_next = False
                 continue
             if a.startswith('-'):
                 split = a.lstrip('-').split('=')
                 alias = split[0]
                 if alias in notebook_aliases:
                     self.kernel_argv.remove(a)
                     if len(split) == 1:
                         # alias passed with arg via space
                         swallow_next = True
 
     def init_configurables(self):
         # Don't let Qt or ZMQ swallow KeyboardInterupts.
         signal.signal(signal.SIGINT, signal.SIG_DFL)
 
         # force Session default to be secure
         default_secure(self.config)
         # Create a KernelManager and start a kernel.
         self.kernel_manager = MappingKernelManager(
             config=self.config, log=self.log, kernel_argv=self.kernel_argv,
             connection_dir = self.profile_dir.security_dir,
         )
         self.notebook_manager = NotebookManager(config=self.config, log=self.log)
         self.notebook_manager.list_notebooks()
 
     def init_logging(self):
         super(NotebookApp, self).init_logging()
         # This prevents double log messages because tornado use a root logger that
         # self.log is a child of. The logging module dipatches log messages to a log
         # and all of its ancenstors until propagate is set to False.
         self.log.propagate = False
 
     @catch_config_error
     def initialize(self, argv=None):
         super(NotebookApp, self).initialize(argv)
         self.init_configurables()
         self.web_app = NotebookWebApplication(
             self, self.kernel_manager, self.notebook_manager, self.log
         )
         if self.certfile:
             ssl_options = dict(certfile=self.certfile)
             if self.keyfile:
                 ssl_options['keyfile'] = self.keyfile
         else:
             ssl_options = None
         self.web_app.password = self.password
         self.http_server = httpserver.HTTPServer(self.web_app, ssl_options=ssl_options)
         if ssl_options is None and not self.ip:
             self.log.critical('WARNING: the notebook server is listening on all IP addresses '
                               'but not using any encryption or authentication. This is highly '
                               'insecure and not recommended.')
 
         # Try random ports centered around the default.
         from random import randint
         n = 50  # Max number of attempts, keep reasonably large.
         for port in range(self.port, self.port+5) + [self.port + randint(-2*n, 2*n) for i in range(n-5)]:
             try:
                 self.http_server.listen(port, self.ip)
             except socket.error, e:
                 if e.errno != errno.EADDRINUSE:
                     raise
                 self.log.info('The port %i is already in use, trying another random port.' % port)
             else:
                 self.port = port
                 break
 
     def start(self):
         ip = self.ip if self.ip else '[all ip addresses on your system]'
         proto = 'https' if self.certfile else 'http'
         self.log.info("The IPython Notebook is running at: %s://%s:%i" % (proto,
                                                                           ip,
                                                                           self.port))
         if self.open_browser:
             ip = self.ip or '127.0.0.1'
             b = lambda : webbrowser.open("%s://%s:%i" % (proto, ip, self.port),
                                          new=2)
             threading.Thread(target=b).start()
 
         ioloop.IOLoop.instance().start()
 
 #-----------------------------------------------------------------------------
 # Main entry point
 #-----------------------------------------------------------------------------
 
 def launch_new_instance():
     app = NotebookApp()
     app.initialize()
     app.start()
 

IPython/zmq/kernelmanager.py

@@ -1,1046 +1,947 b''
 """Base classes to manage the interaction with a running kernel.
 
 TODO
 * Create logger to handle debugging and console messages.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # Standard library imports.
 import errno
 import json
-from Queue import Queue, Empty
 from subprocess import Popen
 import os
 import signal
 import sys
 from threading import Thread
 import time
 
 # System library imports.
 import zmq
-from zmq import POLLIN, POLLOUT, POLLERR
-from zmq.eventloop import ioloop
+from zmq.eventloop import ioloop, zmqstream
 
 # Local imports.
 from IPython.config.loader import Config
 from IPython.utils.localinterfaces import LOCALHOST, LOCAL_IPS
 from IPython.utils.traitlets import (
     HasTraits, Any, Instance, Type, Unicode, Integer, Bool
 )
 from IPython.utils.py3compat import str_to_bytes
 from IPython.zmq.entry_point import write_connection_file
 from session import Session
 
 #-----------------------------------------------------------------------------
 # Constants and exceptions
 #-----------------------------------------------------------------------------
 
 class InvalidPortNumber(Exception):
     pass
 
 #-----------------------------------------------------------------------------
 # Utility functions
 #-----------------------------------------------------------------------------
 
 # some utilities to validate message structure, these might get moved elsewhere
 # if they prove to have more generic utility
 
 def validate_string_list(lst):
     """Validate that the input is a list of strings.
 
     Raises ValueError if not."""
     if not isinstance(lst, list):
         raise ValueError('input %r must be a list' % lst)
     for x in lst:
         if not isinstance(x, basestring):
             raise ValueError('element %r in list must be a string' % x)
 
 
 def validate_string_dict(dct):
     """Validate that the input is a dict with string keys and values.
 
     Raises ValueError if not."""
     for k,v in dct.iteritems():
         if not isinstance(k, basestring):
             raise ValueError('key %r in dict must be a string' % k)
         if not isinstance(v, basestring):
             raise ValueError('value %r in dict must be a string' % v)
 
 
 #-----------------------------------------------------------------------------
 # ZMQ Socket Channel classes
 #-----------------------------------------------------------------------------
 
 class ZMQSocketChannel(Thread):
     """The base class for the channels that use ZMQ sockets.
     """
     context = None
     session = None
     socket = None
     ioloop = None
-    iostate = None
+    stream = None
     _address = None
 
     def __init__(self, context, session, address):
         """Create a channel
 
         Parameters
         ----------
         context : :class:`zmq.Context`
             The ZMQ context to use.
         session : :class:`session.Session`
             The session to use.
         address : tuple
             Standard (ip, port) tuple that the kernel is listening on.
         """
         super(ZMQSocketChannel, self).__init__()
         self.daemon = True
 
         self.context = context
         self.session = session
         if address[1] == 0:
             message = 'The port number for a channel cannot be 0.'
             raise InvalidPortNumber(message)
         self._address = address
 
     def _run_loop(self):
         """Run my loop, ignoring EINTR events in the poller"""
         while True:
             try:
                 self.ioloop.start()
             except zmq.ZMQError as e:
                 if e.errno == errno.EINTR:
                     continue
                 else:
                     raise
             else:
                 break
 
     def stop(self):
         """Stop the channel's activity.
 
         This calls :method:`Thread.join` and returns when the thread
         terminates. :class:`RuntimeError` will be raised if
         :method:`self.start` is called again.
         """
         self.join()
 
     @property
     def address(self):
         """Get the channel's address as an (ip, port) tuple.
 
         By the default, the address is (localhost, 0), where 0 means a random
         port.
         """
         return self._address
 
-    def add_io_state(self, state):
-        """Add IO state to the eventloop.
+    def _queue_send(self, msg):
+        """Queue a message to be sent from the IOLoop's thread.
 
         Parameters
         ----------
-        state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR
-            The IO state flag to set.
+        msg : message to send
 
-        This is thread safe as it uses the thread safe IOLoop.add_callback.
+        This is threadsafe, as it uses IOLoop.add_callback to give the loop's
+        thread control of the action.
         """
-        def add_io_state_callback():
-            if not self.iostate & state:
-                self.iostate = self.iostate | state
-                self.ioloop.update_handler(self.socket, self.iostate)
-        self.ioloop.add_callback(add_io_state_callback)
+        def thread_send():
+            self.session.send(self.stream, msg)
+        self.ioloop.add_callback(thread_send)
 
-    def drop_io_state(self, state):
-        """Drop IO state from the eventloop.
+    def _handle_recv(self, msg):
+        """callback for stream.on_recv
 
-        Parameters
-        ----------
-        state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR
-            The IO state flag to set.
-
-        This is thread safe as it uses the thread safe IOLoop.add_callback.
+        unpacks message, and calls handlers with it.
         """
-        def drop_io_state_callback():
-            if self.iostate & state:
-                self.iostate = self.iostate & (~state)
-                self.ioloop.update_handler(self.socket, self.iostate)
-        self.ioloop.add_callback(drop_io_state_callback)
+        ident,smsg = self.session.feed_identities(msg)
+        self.call_handlers(self.session.unserialize(smsg))
+    
 
 
 class ShellSocketChannel(ZMQSocketChannel):
     """The XREQ channel for issues request/replies to the kernel.
     """
 
     command_queue = None
     # flag for whether execute requests should be allowed to call raw_input:
     allow_stdin = True
 
     def __init__(self, context, session, address):
         super(ShellSocketChannel, self).__init__(context, session, address)
-        self.command_queue = Queue()
         self.ioloop = ioloop.IOLoop()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.DEALER)
         self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
         self.socket.connect('tcp://%s:%i' % self.address)
-        self.iostate = POLLERR|POLLIN
-        self.ioloop.add_handler(self.socket, self._handle_events,
-                                self.iostate)
+        self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
+        self.stream.on_recv(self._handle_recv)
         self._run_loop()
 
     def stop(self):
         self.ioloop.stop()
         super(ShellSocketChannel, self).stop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def execute(self, code, silent=False,
                 user_variables=None, user_expressions=None, allow_stdin=None):
         """Execute code in the kernel.
 
         Parameters
         ----------
         code : str
             A string of Python code.
 
         silent : bool, optional (default False)
             If set, the kernel will execute the code as quietly possible.
 
         user_variables : list, optional
             A list of variable names to pull from the user's namespace.  They
             will come back as a dict with these names as keys and their
             :func:`repr` as values.
 
         user_expressions : dict, optional
             A dict with string keys and  to pull from the user's
             namespace.  They will come back as a dict with these names as keys
             and their :func:`repr` as values.
 
         allow_stdin : bool, optional
             Flag for 
             A dict with string keys and  to pull from the user's
             namespace.  They will come back as a dict with these names as keys
             and their :func:`repr` as values.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         if user_variables is None:
             user_variables = []
         if user_expressions is None:
             user_expressions = {}
         if allow_stdin is None:
             allow_stdin = self.allow_stdin
         
         
         # Don't waste network traffic if inputs are invalid
         if not isinstance(code, basestring):
             raise ValueError('code %r must be a string' % code)
         validate_string_list(user_variables)
         validate_string_dict(user_expressions)
 
         # Create class for content/msg creation. Related to, but possibly
         # not in Session.
         content = dict(code=code, silent=silent,
                        user_variables=user_variables,
                        user_expressions=user_expressions,
                        allow_stdin=allow_stdin,
                        )
         msg = self.session.msg('execute_request', content)
-        self._queue_request(msg)
+        self._queue_send(msg)
         return msg['header']['msg_id']
 
     def complete(self, text, line, cursor_pos, block=None):
         """Tab complete text in the kernel's namespace.
 
         Parameters
         ----------
         text : str
             The text to complete.
         line : str
             The full line of text that is the surrounding context for the
             text to complete.
         cursor_pos : int
             The position of the cursor in the line where the completion was
             requested.
         block : str, optional
             The full block of code in which the completion is being requested.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         content = dict(text=text, line=line, block=block, cursor_pos=cursor_pos)
         msg = self.session.msg('complete_request', content)
-        self._queue_request(msg)
+        self._queue_send(msg)
         return msg['header']['msg_id']
 
     def object_info(self, oname):
         """Get metadata information about an object.
 
         Parameters
         ----------
         oname : str
             A string specifying the object name.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         content = dict(oname=oname)
         msg = self.session.msg('object_info_request', content)
-        self._queue_request(msg)
+        self._queue_send(msg)
         return msg['header']['msg_id']
 
     def history(self, raw=True, output=False, hist_access_type='range', **kwargs):
         """Get entries from the history list.
 
         Parameters
         ----------
         raw : bool
             If True, return the raw input.
         output : bool
             If True, then return the output as well.
         hist_access_type : str
             'range' (fill in session, start and stop params), 'tail' (fill in n)
              or 'search' (fill in pattern param).
 
         session : int
             For a range request, the session from which to get lines. Session
             numbers are positive integers; negative ones count back from the
             current session.
         start : int
             The first line number of a history range.
         stop : int
             The final (excluded) line number of a history range.
 
         n : int
             The number of lines of history to get for a tail request.
 
         pattern : str
             The glob-syntax pattern for a search request.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         content = dict(raw=raw, output=output, hist_access_type=hist_access_type,
                                                                     **kwargs)
         msg = self.session.msg('history_request', content)
-        self._queue_request(msg)
+        self._queue_send(msg)
         return msg['header']['msg_id']
 
     def shutdown(self, restart=False):
         """Request an immediate kernel shutdown.
 
         Upon receipt of the (empty) reply, client code can safely assume that
         the kernel has shut down and it's safe to forcefully terminate it if
         it's still alive.
 
         The kernel will send the reply via a function registered with Python's
         atexit module, ensuring it's truly done as the kernel is done with all
         normal operation.
         """
         # Send quit message to kernel. Once we implement kernel-side setattr,
         # this should probably be done that way, but for now this will do.
         msg = self.session.msg('shutdown_request', {'restart':restart})
-        self._queue_request(msg)
+        self._queue_send(msg)
         return msg['header']['msg_id']
 
-    def _handle_events(self, socket, events):
-        if events & POLLERR:
-            self._handle_err()
-        if events & POLLOUT:
-            self._handle_send()
-        if events & POLLIN:
-            self._handle_recv()
-
-    def _handle_recv(self):
-        ident,msg = self.session.recv(self.socket, 0)
-        self.call_handlers(msg)
-
-    def _handle_send(self):
-        try:
-            msg = self.command_queue.get(False)
-        except Empty:
-            pass
-        else:
-            self.session.send(self.socket,msg)
-        if self.command_queue.empty():
-            self.drop_io_state(POLLOUT)
-
-    def _handle_err(self):
-        # We don't want to let this go silently, so eventually we should log.
-        raise zmq.ZMQError()
-
-    def _queue_request(self, msg):
-        self.command_queue.put(msg)
-        self.add_io_state(POLLOUT)
 
 
 class SubSocketChannel(ZMQSocketChannel):
     """The SUB channel which listens for messages that the kernel publishes.
     """
 
     def __init__(self, context, session, address):
         super(SubSocketChannel, self).__init__(context, session, address)
         self.ioloop = ioloop.IOLoop()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.SUB)
         self.socket.setsockopt(zmq.SUBSCRIBE,b'')
         self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
         self.socket.connect('tcp://%s:%i' % self.address)
-        self.iostate = POLLIN|POLLERR
-        self.ioloop.add_handler(self.socket, self._handle_events,
-                                self.iostate)
+        self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
+        self.stream.on_recv(self._handle_recv)
         self._run_loop()
 
     def stop(self):
         self.ioloop.stop()
         super(SubSocketChannel, self).stop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def flush(self, timeout=1.0):
         """Immediately processes all pending messages on the SUB channel.
 
         Callers should use this method to ensure that :method:`call_handlers`
         has been called for all messages that have been received on the
         0MQ SUB socket of this channel.
 
         This method is thread safe.
 
         Parameters
         ----------
         timeout : float, optional
             The maximum amount of time to spend flushing, in seconds. The
             default is one second.
         """
         # We do the IOLoop callback process twice to ensure that the IOLoop
         # gets to perform at least one full poll.
         stop_time = time.time() + timeout
         for i in xrange(2):
             self._flushed = False
             self.ioloop.add_callback(self._flush)
             while not self._flushed and time.time() < stop_time:
                 time.sleep(0.01)
 
-    def _handle_events(self, socket, events):
-        # Turn on and off POLLOUT depending on if we have made a request
-        if events & POLLERR:
-            self._handle_err()
-        if events & POLLIN:
-            self._handle_recv()
-
-    def _handle_err(self):
-        # We don't want to let this go silently, so eventually we should log.
-        raise zmq.ZMQError()
-
-    def _handle_recv(self):
-        # Get all of the messages we can
-        while True:
-            try:
-                ident,msg = self.session.recv(self.socket)
-            except zmq.ZMQError:
-                # Check the errno?
-                # Will this trigger POLLERR?
-                break
-            else:
-                if msg is None:
-                    break
-                self.call_handlers(msg)
-
     def _flush(self):
         """Callback for :method:`self.flush`."""
+        self.stream.flush()
         self._flushed = True
 
 
 class StdInSocketChannel(ZMQSocketChannel):
     """A reply channel to handle raw_input requests that the kernel makes."""
 
     msg_queue = None
 
     def __init__(self, context, session, address):
         super(StdInSocketChannel, self).__init__(context, session, address)
         self.ioloop = ioloop.IOLoop()
-        self.msg_queue = Queue()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.DEALER)
         self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
         self.socket.connect('tcp://%s:%i' % self.address)
-        self.iostate = POLLERR|POLLIN
-        self.ioloop.add_handler(self.socket, self._handle_events,
-                                self.iostate)
+        self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
+        self.stream.on_recv(self._handle_recv)
         self._run_loop()
 
     def stop(self):
         self.ioloop.stop()
         super(StdInSocketChannel, self).stop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def input(self, string):
         """Send a string of raw input to the kernel."""
         content = dict(value=string)
         msg = self.session.msg('input_reply', content)
-        self._queue_reply(msg)
-
-    def _handle_events(self, socket, events):
-        if events & POLLERR:
-            self._handle_err()
-        if events & POLLOUT:
-            self._handle_send()
-        if events & POLLIN:
-            self._handle_recv()
-
-    def _handle_recv(self):
-        ident,msg = self.session.recv(self.socket, 0)
-        self.call_handlers(msg)
-
-    def _handle_send(self):
-        try:
-            msg = self.msg_queue.get(False)
-        except Empty:
-            pass
-        else:
-            self.session.send(self.socket,msg)
-        if self.msg_queue.empty():
-            self.drop_io_state(POLLOUT)
-
-    def _handle_err(self):
-        # We don't want to let this go silently, so eventually we should log.
-        raise zmq.ZMQError()
-
-    def _queue_reply(self, msg):
-        self.msg_queue.put(msg)
-        self.add_io_state(POLLOUT)
+        self._queue_send(msg)
 
 
 class HBSocketChannel(ZMQSocketChannel):
     """The heartbeat channel which monitors the kernel heartbeat.
 
     Note that the heartbeat channel is paused by default. As long as you start
     this channel, the kernel manager will ensure that it is paused and un-paused
     as appropriate.
     """
 
     time_to_dead = 3.0
     socket = None
     poller = None
     _running = None
     _pause = None
 
     def __init__(self, context, session, address):
         super(HBSocketChannel, self).__init__(context, session, address)
         self._running = False
         self._pause = True
 
     def _create_socket(self):
         self.socket = self.context.socket(zmq.REQ)
         self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
         self.socket.connect('tcp://%s:%i' % self.address)
         self.poller = zmq.Poller()
         self.poller.register(self.socket, zmq.POLLIN)
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self._create_socket()
         self._running = True
         while self._running:
             if self._pause:
                 time.sleep(self.time_to_dead)
             else:
                 since_last_heartbeat = 0.0
                 request_time = time.time()
                 try:
                     #io.rprint('Ping from HB channel') # dbg
                     self.socket.send(b'ping')
                 except zmq.ZMQError, e:
                     #io.rprint('*** HB Error:', e) # dbg
                     if e.errno == zmq.EFSM:
                         #io.rprint('sleep...', self.time_to_dead) # dbg
                         time.sleep(self.time_to_dead)
                         self._create_socket()
                     else:
                         raise
                 else:
                     while True:
                         try:
                             self.socket.recv(zmq.NOBLOCK)
                         except zmq.ZMQError, e:
                             #io.rprint('*** HB Error 2:', e) # dbg
                             if e.errno == zmq.EAGAIN:
                                 before_poll = time.time()
                                 until_dead = self.time_to_dead - (before_poll -
                                                                   request_time)
 
                                 # When the return value of poll() is an empty
                                 # list, that is when things have gone wrong
                                 # (zeromq bug). As long as it is not an empty
                                 # list, poll is working correctly even if it
                                 # returns quickly. Note: poll timeout is in
                                 # milliseconds.
                                 if until_dead > 0.0:
                                     while True:
                                         try:
                                             self.poller.poll(1000 * until_dead)
                                         except zmq.ZMQError as e:
                                             if e.errno == errno.EINTR:
                                                 continue
                                             else:
                                                 raise
                                         else:
                                             break
 
                                 since_last_heartbeat = time.time()-request_time
                                 if since_last_heartbeat > self.time_to_dead:
                                     self.call_handlers(since_last_heartbeat)
                                     break
                             else:
                                 # FIXME: We should probably log this instead.
                                 raise
                         else:
                             until_dead = self.time_to_dead - (time.time() -
                                                               request_time)
                             if until_dead > 0.0:
                                 #io.rprint('sleep...', self.time_to_dead) # dbg
                                 time.sleep(until_dead)
                             break
 
     def pause(self):
         """Pause the heartbeat."""
         self._pause = True
 
     def unpause(self):
         """Unpause the heartbeat."""
         self._pause = False
 
     def is_beating(self):
         """Is the heartbeat running and not paused."""
         if self.is_alive() and not self._pause:
             return True
         else:
             return False
 
     def stop(self):
         self._running = False
         super(HBSocketChannel, self).stop()
 
     def call_handlers(self, since_last_heartbeat):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
 
 #-----------------------------------------------------------------------------
 # Main kernel manager class
 #-----------------------------------------------------------------------------
 
 class KernelManager(HasTraits):
     """ Manages a kernel for a frontend.
 
     The SUB channel is for the frontend to receive messages published by the
     kernel.
 
     The REQ channel is for the frontend to make requests of the kernel.
 
     The REP channel is for the kernel to request stdin (raw_input) from the
     frontend.
     """
     # config object for passing to child configurables
     config = Instance(Config)
 
     # The PyZMQ Context to use for communication with the kernel.
     context = Instance(zmq.Context)
     def _context_default(self):
         return zmq.Context.instance()
 
     # The Session to use for communication with the kernel.
     session = Instance(Session)
 
     # The kernel process with which the KernelManager is communicating.
     kernel = Instance(Popen)
 
     # The addresses for the communication channels.
     connection_file = Unicode('')
     ip = Unicode(LOCALHOST)
     def _ip_changed(self, name, old, new):
         if new == '*':
             self.ip = '0.0.0.0'
     shell_port = Integer(0)
     iopub_port = Integer(0)
     stdin_port = Integer(0)
     hb_port = Integer(0)
 
     # The classes to use for the various channels.
     shell_channel_class = Type(ShellSocketChannel)
     sub_channel_class = Type(SubSocketChannel)
     stdin_channel_class = Type(StdInSocketChannel)
     hb_channel_class = Type(HBSocketChannel)
 
     # Protected traits.
     _launch_args = Any
     _shell_channel = Any
     _sub_channel = Any
     _stdin_channel = Any
     _hb_channel = Any
     _connection_file_written=Bool(False)
 
     def __init__(self, **kwargs):
         super(KernelManager, self).__init__(**kwargs)
         if self.session is None:
             self.session = Session(config=self.config)
     
     def __del__(self):
         if self._connection_file_written:
             # cleanup connection files on full shutdown of kernel we started
             self._connection_file_written = False
             try:
                 os.remove(self.connection_file)
             except IOError:
                 pass
 
 
     #--------------------------------------------------------------------------
     # Channel management methods:
     #--------------------------------------------------------------------------
 
     def start_channels(self, shell=True, sub=True, stdin=True, hb=True):
         """Starts the channels for this kernel.
 
         This will create the channels if they do not exist and then start
         them. If port numbers of 0 are being used (random ports) then you
         must first call :method:`start_kernel`. If the channels have been
         stopped and you call this, :class:`RuntimeError` will be raised.
         """
         if shell:
             self.shell_channel.start()
         if sub:
             self.sub_channel.start()
         if stdin:
             self.stdin_channel.start()
             self.shell_channel.allow_stdin = True
         else:
             self.shell_channel.allow_stdin = False
         if hb:
             self.hb_channel.start()
 
     def stop_channels(self):
         """Stops all the running channels for this kernel.
         """
         if self.shell_channel.is_alive():
             self.shell_channel.stop()
         if self.sub_channel.is_alive():
             self.sub_channel.stop()
         if self.stdin_channel.is_alive():
             self.stdin_channel.stop()
         if self.hb_channel.is_alive():
             self.hb_channel.stop()
 
     @property
     def channels_running(self):
         """Are any of the channels created and running?"""
         return (self.shell_channel.is_alive() or self.sub_channel.is_alive() or
                 self.stdin_channel.is_alive() or self.hb_channel.is_alive())
 
     #--------------------------------------------------------------------------
     # Kernel process management methods:
     #--------------------------------------------------------------------------
     
     def load_connection_file(self):
         """load connection info from JSON dict in self.connection_file"""
         with open(self.connection_file) as f:
             cfg = json.loads(f.read())
         
         self.ip = cfg['ip']
         self.shell_port = cfg['shell_port']
         self.stdin_port = cfg['stdin_port']
         self.iopub_port = cfg['iopub_port']
         self.hb_port = cfg['hb_port']
         self.session.key = str_to_bytes(cfg['key'])
     
     def write_connection_file(self):
         """write connection info to JSON dict in self.connection_file"""
         if self._connection_file_written:
             return
         self.connection_file,cfg = write_connection_file(self.connection_file,
             ip=self.ip, key=self.session.key,
             stdin_port=self.stdin_port, iopub_port=self.iopub_port,
             shell_port=self.shell_port, hb_port=self.hb_port)
         # write_connection_file also sets default ports:
         self.shell_port = cfg['shell_port']
         self.stdin_port = cfg['stdin_port']
         self.iopub_port = cfg['iopub_port']
         self.hb_port = cfg['hb_port']
         
         self._connection_file_written = True
     
     def start_kernel(self, **kw):
         """Starts a kernel process and configures the manager to use it.
 
         If random ports (port=0) are being used, this method must be called
         before the channels are created.
 
         Parameters:
         -----------
         ipython : bool, optional (default True)
              Whether to use an IPython kernel instead of a plain Python kernel.
 
         launcher : callable, optional (default None)
              A custom function for launching the kernel process (generally a
              wrapper around ``entry_point.base_launch_kernel``). In most cases,
              it should not be necessary to use this parameter.
 
         **kw : optional
              See respective options for IPython and Python kernels.
         """
         if self.ip not in LOCAL_IPS:
             raise RuntimeError("Can only launch a kernel on a local interface. "
                                "Make sure that the '*_address' attributes are "
                                "configured properly. "
                                "Currently valid addresses are: %s"%LOCAL_IPS
                                )
         
         # write connection file / get default ports
         self.write_connection_file()
 
         self._launch_args = kw.copy()
         launch_kernel = kw.pop('launcher', None)
         if launch_kernel is None:
             if kw.pop('ipython', True):
                 from ipkernel import launch_kernel
             else:
                 from pykernel import launch_kernel
         self.kernel = launch_kernel(fname=self.connection_file, **kw)
 
     def shutdown_kernel(self, restart=False):
         """ Attempts to the stop the kernel process cleanly. If the kernel
         cannot be stopped, it is killed, if possible.
         """
         # FIXME: Shutdown does not work on Windows due to ZMQ errors!
         if sys.platform == 'win32':
             self.kill_kernel()
             return
 
         # Pause the heart beat channel if it exists.
         if self._hb_channel is not None:
             self._hb_channel.pause()
 
         # Don't send any additional kernel kill messages immediately, to give
         # the kernel a chance to properly execute shutdown actions. Wait for at
         # most 1s, checking every 0.1s.
         self.shell_channel.shutdown(restart=restart)
         for i in range(10):
             if self.is_alive:
                 time.sleep(0.1)
             else:
                 break
         else:
             # OK, we've waited long enough.
             if self.has_kernel:
                 self.kill_kernel()
 
         if not restart and self._connection_file_written:
             # cleanup connection files on full shutdown of kernel we started
             self._connection_file_written = False
             try:
                 os.remove(self.connection_file)
             except IOError:
                 pass
 
     def restart_kernel(self, now=False, **kw):
         """Restarts a kernel with the arguments that were used to launch it.
 
         If the old kernel was launched with random ports, the same ports will be
         used for the new kernel.
 
         Parameters
         ----------
         now : bool, optional
             If True, the kernel is forcefully restarted *immediately*, without
             having a chance to do any cleanup action.  Otherwise the kernel is
             given 1s to clean up before a forceful restart is issued.
 
             In all cases the kernel is restarted, the only difference is whether
             it is given a chance to perform a clean shutdown or not.
 
         **kw : optional
             Any options specified here will replace those used to launch the
             kernel.
         """
         if self._launch_args is None:
             raise RuntimeError("Cannot restart the kernel. "
                                "No previous call to 'start_kernel'.")
         else:
             # Stop currently running kernel.
             if self.has_kernel:
                 if now:
                     self.kill_kernel()
                 else:
                     self.shutdown_kernel(restart=True)
 
             # Start new kernel.
             self._launch_args.update(kw)
             self.start_kernel(**self._launch_args)
 
             # FIXME: Messages get dropped in Windows due to probable ZMQ bug
             # unless there is some delay here.
             if sys.platform == 'win32':
                 time.sleep(0.2)
 
     @property
     def has_kernel(self):
         """Returns whether a kernel process has been specified for the kernel
         manager.
         """
         return self.kernel is not None
 
     def kill_kernel(self):
         """ Kill the running kernel. """
         if self.has_kernel:
             # Pause the heart beat channel if it exists.
             if self._hb_channel is not None:
                 self._hb_channel.pause()
 
             # Attempt to kill the kernel.
             try:
                 self.kernel.kill()
             except OSError, e:
                 # In Windows, we will get an Access Denied error if the process
                 # has already terminated. Ignore it.
                 if sys.platform == 'win32':
                     if e.winerror != 5:
                         raise
                 # On Unix, we may get an ESRCH error if the process has already
                 # terminated. Ignore it.
                 else:
                     from errno import ESRCH
                     if e.errno != ESRCH:
                         raise
             self.kernel = None
         else:
             raise RuntimeError("Cannot kill kernel. No kernel is running!")
 
     def interrupt_kernel(self):
         """ Interrupts the kernel. Unlike ``signal_kernel``, this operation is
         well supported on all platforms.
         """
         if self.has_kernel:
             if sys.platform == 'win32':
                 from parentpoller import ParentPollerWindows as Poller
                 Poller.send_interrupt(self.kernel.win32_interrupt_event)
             else:
                 self.kernel.send_signal(signal.SIGINT)
         else:
             raise RuntimeError("Cannot interrupt kernel. No kernel is running!")
 
     def signal_kernel(self, signum):
         """ Sends a signal to the kernel. Note that since only SIGTERM is
         supported on Windows, this function is only useful on Unix systems.
         """
         if self.has_kernel:
             self.kernel.send_signal(signum)
         else:
             raise RuntimeError("Cannot signal kernel. No kernel is running!")
 
     @property
     def is_alive(self):
         """Is the kernel process still running?"""
         # FIXME: not using a heartbeat means this method is broken for any
         # remote kernel, it's only capable of handling local kernels.
         if self.has_kernel:
             if self.kernel.poll() is None:
                 return True
             else:
                 return False
         else:
             # We didn't start the kernel with this KernelManager so we don't
             # know if it is running. We should use a heartbeat for this case.
             return True
 
     #--------------------------------------------------------------------------
     # Channels used for communication with the kernel:
     #--------------------------------------------------------------------------
 
     @property
     def shell_channel(self):
         """Get the REQ socket channel object to make requests of the kernel."""
         if self._shell_channel is None:
             self._shell_channel = self.shell_channel_class(self.context,
                                                          self.session,
                                                          (self.ip, self.shell_port))
         return self._shell_channel
 
     @property
     def sub_channel(self):
         """Get the SUB socket channel object."""
         if self._sub_channel is None:
             self._sub_channel = self.sub_channel_class(self.context,
                                                        self.session,
                                                        (self.ip, self.iopub_port))
         return self._sub_channel
 
     @property
     def stdin_channel(self):
         """Get the REP socket channel object to handle stdin (raw_input)."""
         if self._stdin_channel is None:
             self._stdin_channel = self.stdin_channel_class(self.context,
                                                        self.session,
                                                        (self.ip, self.stdin_port))
         return self._stdin_channel
 
     @property
     def hb_channel(self):
         """Get the heartbeat socket channel object to check that the
         kernel is alive."""
         if self._hb_channel is None:
             self._hb_channel = self.hb_channel_class(self.context,
                                                        self.session,
                                                        (self.ip, self.hb_port))
         return self._hb_channel