Added support for multiple kernels.

IPython/html/static/notebook/js/widgetmanager.js

@@ -1,204 +1,205
 //----------------------------------------------------------------------------
 //  Copyright (C) 2013  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.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // WidgetModel, WidgetView, and WidgetManager
 //============================================================================
 /**
  * Base Widget classes
  * @module IPython
  * @namespace IPython
  * @submodule widget
  */
 
 (function () {
     "use strict";
 
     // Use require.js 'define' method so that require.js is intelligent enough to
     // syncronously load everything within this file when it is being 'required' 
     // elsewhere.
     define(["underscore",
              "backbone",
             ], function (underscore, backbone) {
             
-        // Backbone.sync method must be in widgetmanager.js file instead of 
-        // widget.js so it can be overwritten for different contexts.
         Backbone.sync = function (method, model, options) {
+            // Sync widget models to back-end.
+            //
+            // Backbone.sync method must be in widgetmanager.js file instead of 
+            // widget.js so it can be overwritten for different contexts.
             var result = model._handle_sync(method, options);
             if (options.success) {
                 options.success(result);
             }
         }; 
 
+
         //--------------------------------------------------------------------
         // WidgetManager class
         //--------------------------------------------------------------------
-        var WidgetManager = function () {
-            this.comm_manager = null;
-            this._model_types = {}; /* Dictionary of model type names 
-                                      (target_name) and model types. */
-            this._view_types = {}; /* Dictionary of view names and view types. */
-            this._models = {}; /* Dictionary of model ids and model instances */
-        };
-
+        var WidgetManager = function (comm_manager) {
+            // Public constructor
+            WidgetManager._managers.push(this);
 
-        WidgetManager.prototype.attach_comm_manager = function (comm_manager) {
+            // Attach a comm manager to the 
             this.comm_manager = comm_manager;
 
             // Register already-registered widget model types with the comm manager.
-            for (var widget_model_name in this._model_types) {
-                // TODO: Should not be a for.
-                this.comm_manager.register_target(widget_model_name, $.proxy(this._handle_comm_open, this));
+            for (var name in WidgetManager._model_types) {
+                if (WidgetManager._model_types.hasOwnProperty(name)) {
+                    this.comm_manager.register_target(name, $.proxy(this._handle_comm_open, this));
+
+                }
             }
         };
 
+        //--------------------------------------------------------------------
+        // Class level
+        //--------------------------------------------------------------------
+        WidgetManager._model_types = {}; /* Dictionary of model type names (target_name) and model types. */
+        WidgetManager._view_types = {}; /* Dictionary of view names and view types. */
+        WidgetManager._models = {}; /* Dictionary of model ids and model instances */
+        WidgetManager._managers = []; /* List of widget managers */
+
+        WidgetManager.register_widget_model = function (model_name, model_type) {
+            // Registers a widget model by name.
+            WidgetManager._model_types[model_name] = model_type;
 
-        WidgetManager.prototype.register_widget_model = function (widget_model_name, widget_model_type) {
             // Register the widget with the comm manager.  Make sure to pass this object's context
             // in so `this` works in the call back.
-            if (this.comm_manager !== null) {
-                this.comm_manager.register_target(widget_model_name, $.proxy(this._handle_comm_open, this));
+            for (var i = 0; i < WidgetManager._managers.length; i++) {
+                var instance = WidgetManager._managers[i];
+                if (instance.comm_manager !== null) {
+                    instance.comm_manager.register_target(model_name, $.proxy(instance._handle_comm_open, instance));
+                }
             }
-            this._model_types[widget_model_name] = widget_model_type;
         };
 
-
-        WidgetManager.prototype.register_widget_view = function (widget_view_name, widget_view_type) {
-            this._view_types[widget_view_name] = widget_view_type;
+        WidgetManager.register_widget_view = function (view_name, view_type) {
+            // Registers a widget view by name.
+            WidgetManager._view_types[view_name] = view_type;
         };
 
-
+        //--------------------------------------------------------------------
+        // Instance level
+        //--------------------------------------------------------------------
         WidgetManager.prototype.display_view = function(msg, model) {
             var cell = this.get_msg_cell(msg.parent_header.msg_id);
             if (cell === null) {
                 console.log("Could not determine where the display" + 
                     " message was from.  Widget will not be displayed");
             } else {
                 var view = this.create_view(model, {cell: cell});
                 if (view === undefined) {
                     console.error("View creation failed", model);
                 }
                 if (cell.widget_subarea !== undefined
                     && cell.widget_subarea !== null) {
                     
                     cell.widget_area.show();
                     cell.widget_subarea.append(view.$el);
                 }
             }
         },
 
-
         WidgetManager.prototype.create_view = function(model, options) {
             var view_name = model.get('view_name');
-            var ViewType = this._view_types[view_name];
+            var ViewType = WidgetManager._view_types[view_name];
             if (ViewType !== undefined && ViewType !== null) {
                 var parameters = {model: model, options: options};
                 var view = new ViewType(parameters);
                 view.render();
                 IPython.keyboard_manager.register_events(view.$el);
                 model.views.push(view);
                 model.on('destroy', view.remove, view);
                 return view;
             }
         },
 
-
         WidgetManager.prototype.get_msg_cell = function (msg_id) {
             var cell = null;
             // First, check to see if the msg was triggered by cell execution.
             if (IPython.notebook !== undefined && IPython.notebook !== null) {
                 cell = IPython.notebook.get_msg_cell(msg_id);
             }
             if (cell !== null) {
                 return cell
             }
             // Second, check to see if a get_cell callback was defined
             // for the message.  get_cell callbacks are registered for
             // widget messages, so this block is actually checking to see if the
             // message was triggered by a widget.
-            var kernel = null;
-            if (this.comm_manager !== null) {
-                kernel = this.comm_manager.kernel;
-            }
+            var kernel = this.comm_manager.kernel;
             if (kernel !== undefined && kernel !== null) {
                 var callbacks = kernel.get_callbacks_for_msg(msg_id);
                 if (callbacks !== undefined && 
                     callbacks.iopub !== undefined && 
                     callbacks.iopub.get_cell !== undefined) {
 
                     return callbacks.iopub.get_cell();
                 }    
             }
             
             // Not triggered by a cell or widget (no get_cell callback 
             // exists).
             return null;
         };
 
         WidgetManager.prototype.callbacks = function (view) {
             // callback handlers specific a view
             var callbacks = {};
             var cell = view.options.cell;
             if (cell !== null) {
                 // Try to get output handlers
                 var handle_output = null;
                 var handle_clear_output = null;
                 if (cell.output_area !== undefined && cell.output_area !== null) {
                     handle_output = $.proxy(cell.output_area.handle_output, cell.output_area);
                     handle_clear_output = $.proxy(cell.output_area.handle_clear_output, cell.output_area);
                 }
 
                 // Create callback dict using what is known
                 var that = this;
                 callbacks = {
                     iopub : {
                         output : handle_output,
                         clear_output : handle_clear_output,
 
                         status : function (msg) {
                             view.model._handle_status(msg, that.callbacks(view));
                         },
 
                         // Special function only registered by widget messages.
                         // Allows us to get the cell for a message so we know
                         // where to add widgets if the code requires it.
                         get_cell : function () {
                             return cell;
                         },
                     },
                 };
             }
             return callbacks;
         };
 
-
         WidgetManager.prototype.get_model = function (model_id) {
-            var model = this._models[model_id];
+            var model = WidgetManager._models[model_id];
             if (model !== undefined && model.id == model_id) {
                 return model;
             }
             return null;
         };
 
-
         WidgetManager.prototype._handle_comm_open = function (comm, msg) {
+            var model_id = comm.comm_id;
             var widget_type_name = msg.content.target_name;
-            var widget_model = new this._model_types[widget_type_name](this, comm.comm_id, comm);
-            this._models[comm.comm_id] = widget_model; // comm_id == model_id
+            var widget_model = new WidgetManager._model_types[widget_type_name](this, model_id, comm);
+            WidgetManager._models[model_id] = widget_model;
         };
         
-        //--------------------------------------------------------------------
-        // Init code
-        //--------------------------------------------------------------------
         IPython.WidgetManager = WidgetManager;
-        if (IPython.widget_manager === undefined || IPython.widget_manager === null) {
-            IPython.widget_manager = new WidgetManager();    
-        }
-
-        return IPython.widget_manager;
+        return IPython.WidgetManager;
     });
 }());

IPython/html/static/services/kernels/js/kernel.js

@@ -1,587 +1,585
 //----------------------------------------------------------------------------
 //  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.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // Kernel
 //============================================================================
 
 /**
  * @module IPython
  * @namespace IPython
  * @submodule Kernel
  */
 
 var IPython = (function (IPython) {
     "use strict";
     
     var utils = IPython.utils;
 
     // Initialization and connection.
     /**
      * A Kernel Class to communicate with the Python kernel
      * @Class Kernel
      */
     var Kernel = function (base_url) {
         this.kernel_id = null;
         this.shell_channel = null;
         this.iopub_channel = null;
         this.stdin_channel = null;
         this.base_url = base_url;
         this.running = false;
         this.username = "username";
         this.session_id = utils.uuid();
         this._msg_callbacks = {};
 
         if (typeof(WebSocket) !== 'undefined') {
             this.WebSocket = WebSocket;
         } else if (typeof(MozWebSocket) !== 'undefined') {
             this.WebSocket = MozWebSocket;
         } else {
             alert('Your browser does not have WebSocket support, please try Chrome, Safari or Firefox ≥ 6. Firefox 4 and 5 are also supported by you have to enable WebSockets in about:config.');
         }
         
         this.bind_events();
         this.init_iopub_handlers();
         this.comm_manager = new IPython.CommManager(this);
-        // TODO: make the comm manager an arg to the widget manager initialization
-        this.widget_manager = new IPython.WidgetManager();
-        this.widget_manager.attach_comm_manager(this.comm_manager);
+        this.widget_manager = new IPython.WidgetManager(this.comm_manager);
     };
 
 
     Kernel.prototype._get_msg = function (msg_type, content, metadata) {
         var msg = {
             header : {
                 msg_id : utils.uuid(),
                 username : this.username,
                 session : this.session_id,
                 msg_type : msg_type
             },
             metadata : metadata || {},
             content : content,
             parent_header : {}
         };
         return msg;
     };
     
     Kernel.prototype.bind_events = function () {
         var that = this;
         $([IPython.events]).on('send_input_reply.Kernel', function(evt, data) { 
             that.send_input_reply(data);
         });
     };
     
     // Initialize the iopub handlers
     
     Kernel.prototype.init_iopub_handlers = function () {
         var output_types = ['stream', 'display_data', 'pyout', 'pyerr'];
         this._iopub_handlers = {};
         this.register_iopub_handler('status', $.proxy(this._handle_status_message, this));
         this.register_iopub_handler('clear_output', $.proxy(this._handle_clear_output, this));
         
         for (var i=0; i < output_types.length; i++) {
             this.register_iopub_handler(output_types[i], $.proxy(this._handle_output_message, this));
         }
     };
 
     /**
      * Start the Python kernel
      * @method start
      */
     Kernel.prototype.start = function (params) {
         params = params || {};
         if (!this.running) {
             var qs = $.param(params);
             var url = this.base_url + '?' + qs;
             $.post(url,
                 $.proxy(this._kernel_started, this),
                 'json'
             );
         }
     };
 
     /**
      * Restart the python kernel.
      *
      * Emit a 'status_restarting.Kernel' event with
      * the current object as parameter
      *
      * @method restart
      */
     Kernel.prototype.restart = function () {
         $([IPython.events]).trigger('status_restarting.Kernel', {kernel: this});
         if (this.running) {
             this.stop_channels();
             var url = utils.url_join_encode(this.kernel_url, "restart");
             $.post(url,
                 $.proxy(this._kernel_started, this),
                 'json'
             );
         }
     };
 
 
     Kernel.prototype._kernel_started = function (json) {
         console.log("Kernel started: ", json.id);
         this.running = true;
         this.kernel_id = json.id;
         var ws_url = json.ws_url;
         if (ws_url.match(/wss?:\/\//) === null) {
             // trailing 's' in https will become wss for secure web sockets
             var prot = location.protocol.replace('http', 'ws') + "//";
             ws_url = prot + location.host + ws_url;
         }
         this.ws_url = ws_url;
         this.kernel_url = utils.url_join_encode(this.base_url, this.kernel_id);
         this.start_channels();
     };
 
 
     Kernel.prototype._websocket_closed = function(ws_url, early) {
         this.stop_channels();
         $([IPython.events]).trigger('websocket_closed.Kernel',
             {ws_url: ws_url, kernel: this, early: early}
         );
     };
 
     /**
      * Start the `shell`and `iopub` channels.
      * Will stop and restart them if they already exist.
      *
      * @method start_channels
      */
     Kernel.prototype.start_channels = function () {
         var that = this;
         this.stop_channels();
         var ws_url = this.ws_url + this.kernel_url;
         console.log("Starting WebSockets:", ws_url);
         this.shell_channel = new this.WebSocket(ws_url + "/shell");
         this.stdin_channel = new this.WebSocket(ws_url + "/stdin");
         this.iopub_channel = new this.WebSocket(ws_url + "/iopub");
         
         var already_called_onclose = false; // only alert once
         var ws_closed_early = function(evt){
             if (already_called_onclose){
                 return;
             }
             already_called_onclose = true;
             if ( ! evt.wasClean ){
                 that._websocket_closed(ws_url, true);
             }
         };
         var ws_closed_late = function(evt){
             if (already_called_onclose){
                 return;
             }
             already_called_onclose = true;
             if ( ! evt.wasClean ){
                 that._websocket_closed(ws_url, false);
             }
         };
         var channels = [this.shell_channel, this.iopub_channel, this.stdin_channel];
         for (var i=0; i < channels.length; i++) {
             channels[i].onopen = $.proxy(this._ws_opened, this);
             channels[i].onclose = ws_closed_early;
         }
         // switch from early-close to late-close message after 1s
         setTimeout(function() {
             for (var i=0; i < channels.length; i++) {
                 if (channels[i] !== null) {
                     channels[i].onclose = ws_closed_late;
                 }
             }
         }, 1000);
         this.shell_channel.onmessage = $.proxy(this._handle_shell_reply, this);
         this.iopub_channel.onmessage = $.proxy(this._handle_iopub_message, this);
         this.stdin_channel.onmessage = $.proxy(this._handle_input_request, this);
     };
 
     /**
      * Handle a websocket entering the open state
      * sends session and cookie authentication info as first message.
      * Once all sockets are open, signal the Kernel.status_started event.
      * @method _ws_opened
      */
     Kernel.prototype._ws_opened = function (evt) {
         // send the session id so the Session object Python-side
         // has the same identity
         evt.target.send(this.session_id + ':' + document.cookie);
         
         var channels = [this.shell_channel, this.iopub_channel, this.stdin_channel];
         for (var i=0; i < channels.length; i++) {
             // if any channel is not ready, don't trigger event.
             if ( !channels[i].readyState ) return;
         }
         // all events ready, trigger started event.
         $([IPython.events]).trigger('status_started.Kernel', {kernel: this});
     };
     
     /**
      * Stop the websocket channels.
      * @method stop_channels
      */
     Kernel.prototype.stop_channels = function () {
         var channels = [this.shell_channel, this.iopub_channel, this.stdin_channel];
         for (var i=0; i < channels.length; i++) {
             if ( channels[i] !== null ) {
                 channels[i].onclose = null;
                 channels[i].close();
             }
         }
         this.shell_channel = this.iopub_channel = this.stdin_channel = null;
     };
 
     // Main public methods.
     
     // send a message on the Kernel's shell channel
     Kernel.prototype.send_shell_message = function (msg_type, content, callbacks, metadata) {
         var msg = this._get_msg(msg_type, content, metadata);
         this.shell_channel.send(JSON.stringify(msg));
         this.set_callbacks_for_msg(msg.header.msg_id, callbacks);
         return msg.header.msg_id;
     };
 
     /**
      * Get info on an object
      *
      * @param objname {string}
      * @param callback {function}
      * @method object_info
      *
      * When calling this method, pass a callback function that expects one argument.
      * The callback will be passed the complete `object_info_reply` message documented
      * [here](http://ipython.org/ipython-doc/dev/development/messaging.html#object-information)
      */
     Kernel.prototype.object_info = function (objname, callback) {
         var callbacks;
         if (callback) {
             callbacks = { shell : { reply : callback } };
         }
         
         if (typeof(objname) !== null && objname !== null) {
             var content = {
                 oname : objname.toString(),
                 detail_level : 0,
             };
             return this.send_shell_message("object_info_request", content, callbacks);
         }
         return;
     };
 
     /**
      * Execute given code into kernel, and pass result to callback.
      *
      * @async
      * @method execute
      * @param {string} code
      * @param [callbacks] {Object} With the following keys (all optional)
      *      @param callbacks.shell.reply {function}
      *      @param callbacks.shell.payload.[payload_name] {function}
      *      @param callbacks.iopub.output {function}
      *      @param callbacks.iopub.clear_output {function}
      *      @param callbacks.input {function}
      * @param {object} [options]
      *      @param [options.silent=false] {Boolean}
      *      @param [options.user_expressions=empty_dict] {Dict}
      *      @param [options.user_variables=empty_list] {List od Strings}
      *      @param [options.allow_stdin=false] {Boolean} true|false
      *
      * @example
      *
      * The options object should contain the options for the execute call. Its default
      * values are:
      *
      *      options = {
      *        silent : true,
      *        user_variables : [],
      *        user_expressions : {},
      *        allow_stdin : false
      *      }
      *
      * When calling this method pass a callbacks structure of the form:
      *
      *      callbacks = {
      *       shell : {
      *         reply : execute_reply_callback,
      *         payload : {
      *           set_next_input : set_next_input_callback,
      *         }
      *       },
      *       iopub : {
      *         output : output_callback,
      *         clear_output : clear_output_callback,
      *       },
      *       input : raw_input_callback
      *      }
      *
      * Each callback will be passed the entire message as a single arugment.
      * Payload handlers will be passed the corresponding payload and the execute_reply message.
      */
     Kernel.prototype.execute = function (code, callbacks, options) {
 
         var content = {
             code : code,
             silent : true,
             store_history : false,
             user_variables : [],
             user_expressions : {},
             allow_stdin : false
         };
         callbacks = callbacks || {};
         if (callbacks.input !== undefined) {
             content.allow_stdin = true;
         }
         $.extend(true, content, options);
         $([IPython.events]).trigger('execution_request.Kernel', {kernel: this, content:content});
         return this.send_shell_message("execute_request", content, callbacks);
     };
 
     /**
      * When calling this method, pass a function to be called with the `complete_reply` message
      * as its only argument when it arrives.
      *
      * `complete_reply` is documented
      * [here](http://ipython.org/ipython-doc/dev/development/messaging.html#complete)
      *
      * @method complete
      * @param line {integer}
      * @param cursor_pos {integer}
      * @param callback {function}
      *
      */
     Kernel.prototype.complete = function (line, cursor_pos, callback) {
         var callbacks;
         if (callback) {
             callbacks = { shell : { reply : callback } };
         }
         var content = {
             text : '',
             line : line,
             block : null,
             cursor_pos : cursor_pos
         };
         return this.send_shell_message("complete_request", content, callbacks);
     };
 
 
     Kernel.prototype.interrupt = function () {
         if (this.running) {
             $([IPython.events]).trigger('status_interrupting.Kernel', {kernel: this});
             $.post(this.kernel_url + "/interrupt");
         }
     };
 
 
     Kernel.prototype.kill = function () {
         if (this.running) {
             this.running = false;
             var settings = {
                 cache : false,
                 type : "DELETE"
             };
             $.ajax(this.kernel_url, settings);
         }
     };
 
     Kernel.prototype.send_input_reply = function (input) {
         var content = {
             value : input,
         };
         $([IPython.events]).trigger('input_reply.Kernel', {kernel: this, content:content});
         var msg = this._get_msg("input_reply", content);
         this.stdin_channel.send(JSON.stringify(msg));
         return msg.header.msg_id;
     };
 
 
     // Reply handlers
 
     Kernel.prototype.register_iopub_handler = function (msg_type, callback) {
         this._iopub_handlers[msg_type] = callback;
     };
 
     Kernel.prototype.get_iopub_handler = function (msg_type) {
         // get iopub handler for a specific message type
         return this._iopub_handlers[msg_type];
     };
 
 
     Kernel.prototype.get_callbacks_for_msg = function (msg_id) {
         // get callbacks for a specific message
         return this._msg_callbacks[msg_id];
     };
 
 
     Kernel.prototype.clear_callbacks_for_msg = function (msg_id) {
         if (this._msg_callbacks[msg_id] !== undefined ) {
             delete this._msg_callbacks[msg_id];
         }
     };
     
     /* Set callbacks for a particular message.
      * Callbacks should be a struct of the following form:
      * shell : {
      * 
      * }
     
      */
     Kernel.prototype.set_callbacks_for_msg = function (msg_id, callbacks) {
         if (callbacks) {
             // shallow-copy mapping, because we will modify it at the top level
             var cbcopy = this._msg_callbacks[msg_id] = {};
             cbcopy.shell = callbacks.shell;
             cbcopy.iopub = callbacks.iopub;
             cbcopy.input = callbacks.input;
             this._msg_callbacks[msg_id] = cbcopy;
         }
     };
 
 
     Kernel.prototype._handle_shell_reply = function (e) {
         var reply = $.parseJSON(e.data);
         $([IPython.events]).trigger('shell_reply.Kernel', {kernel: this, reply:reply});
         var content = reply.content;
         var metadata = reply.metadata;
         var parent_id = reply.parent_header.msg_id;
         var callbacks = this.get_callbacks_for_msg(parent_id);
         if (!callbacks || !callbacks.shell) {
             return;
         }
         var shell_callbacks = callbacks.shell;
         
         // clear callbacks on shell
         delete callbacks.shell;
         delete callbacks.input;
         if (!callbacks.iopub) {
             this.clear_callbacks_for_msg(parent_id);
         }
         
         if (shell_callbacks.reply !== undefined) {
             shell_callbacks.reply(reply);
         }
         if (content.payload && shell_callbacks.payload) {
             this._handle_payloads(content.payload, shell_callbacks.payload, reply);
         }
     };
 
 
     Kernel.prototype._handle_payloads = function (payloads, payload_callbacks, msg) {
         var l = payloads.length;
         // Payloads are handled by triggering events because we don't want the Kernel
         // to depend on the Notebook or Pager classes.
         for (var i=0; i<l; i++) {
             var payload = payloads[i];
             var callback = payload_callbacks[payload.source];
             if (callback) {
                 callback(payload, msg);
             }
         }
     };
 
     Kernel.prototype._handle_status_message = function (msg) {
         var execution_state = msg.content.execution_state;
         var parent_id = msg.parent_header.msg_id;
         
         // dispatch status msg callbacks, if any
         var callbacks = this.get_callbacks_for_msg(parent_id);
         if (callbacks && callbacks.iopub && callbacks.iopub.status) {
             try {
                 callbacks.iopub.status(msg);
             } catch (e) {
                 console.log("Exception in status msg handler", e, e.stack);
             }
         }
         
         if (execution_state === 'busy') {
             $([IPython.events]).trigger('status_busy.Kernel', {kernel: this});
         } else if (execution_state === 'idle') {
             // clear callbacks on idle, there can be no more
             if (callbacks !== undefined) {
                 delete callbacks.iopub;
                 delete callbacks.input;
                 if (!callbacks.shell) {
                     this.clear_callbacks_for_msg(parent_id);
                 }
             }
             // trigger status_idle event
             $([IPython.events]).trigger('status_idle.Kernel', {kernel: this});
         } else if (execution_state === 'restarting') {
             // autorestarting is distinct from restarting,
             // in that it means the kernel died and the server is restarting it.
             // status_restarting sets the notification widget,
             // autorestart shows the more prominent dialog.
             $([IPython.events]).trigger('status_autorestarting.Kernel', {kernel: this});
             $([IPython.events]).trigger('status_restarting.Kernel', {kernel: this});
         } else if (execution_state === 'dead') {
             this.stop_channels();
             $([IPython.events]).trigger('status_dead.Kernel', {kernel: this});
         }
     };
     
     
     // handle clear_output message
     Kernel.prototype._handle_clear_output = function (msg) {
         var callbacks = this.get_callbacks_for_msg(msg.parent_header.msg_id);
         if (!callbacks || !callbacks.iopub) {
             return;
         }
         var callback = callbacks.iopub.clear_output;
         if (callback) {
             callback(msg);
         }
     };
 
 
     // handle an output message (pyout, display_data, etc.)
     Kernel.prototype._handle_output_message = function (msg) {
         var callbacks = this.get_callbacks_for_msg(msg.parent_header.msg_id);
         if (!callbacks || !callbacks.iopub) {
             return;
         }
         var callback = callbacks.iopub.output;
         if (callback) {
             callback(msg);
         }
     };
 
     // dispatch IOPub messages to respective handlers.
     // each message type should have a handler.
     Kernel.prototype._handle_iopub_message = function (e) {
         var msg = $.parseJSON(e.data);
 
         var handler = this.get_iopub_handler(msg.header.msg_type);
         if (handler !== undefined) {
             handler(msg);
         }
     };
 
 
     Kernel.prototype._handle_input_request = function (e) {
         var request = $.parseJSON(e.data);
         var header = request.header;
         var content = request.content;
         var metadata = request.metadata;
         var msg_type = header.msg_type;
         if (msg_type !== 'input_request') {
             console.log("Invalid input request!", request);
             return;
         }
         var callbacks = this.get_callbacks_for_msg(request.parent_header.msg_id);
         if (callbacks) {
             if (callbacks.input) {
                 callbacks.input(request);
             }
         }
     };
 
 
     IPython.Kernel = Kernel;
 
     return IPython;
 
 }(IPython));