Merge pull request #7757 from jasongrout/custom-serialization

Custom serialization

IPython/html/static/widgets/js/init.js

@@ -3,6 +3,7 b''
 
 define([
     "widgets/js/manager",
+    "widgets/js/widget",
     "widgets/js/widget_link",
     "widgets/js/widget_bool",
     "widgets/js/widget_button",
@@ -14,21 +15,20 b' define(['
     "widgets/js/widget_selection",
     "widgets/js/widget_selectioncontainer",
     "widgets/js/widget_string",
-], function(widgetmanager, linkModels) {
-    for (var target_name in linkModels) {
-        if (linkModels.hasOwnProperty(target_name)) {
-            widgetmanager.WidgetManager.register_widget_model(target_name, linkModels[target_name]);
-        }
-    }
-
-    // Register all of the loaded views with the widget manager.
+], function(widgetmanager, widget) {
+    // Register all of the loaded models and views with the widget manager.
     for (var i = 2; i < arguments.length; i++) {
-        for (var target_name in arguments[i]) {
-            if (arguments[i].hasOwnProperty(target_name)) {
-                widgetmanager.WidgetManager.register_widget_view(target_name, arguments[i][target_name]);
+        var module = arguments[i];
+        for (var target_name in module) {
+            if (module.hasOwnProperty(target_name)) {
+                var target = module[target_name];
+                if (target.prototype instanceof widget.WidgetModel) {
+                    widgetmanager.WidgetManager.register_widget_model(target_name, target);
+                } else if (target.prototype instanceof widget.WidgetView) {
+                    widgetmanager.WidgetManager.register_widget_view(target_name, target);
+                }
             }
         }
     }
-
     return {'WidgetManager': widgetmanager.WidgetManager}; 
 });

IPython/html/static/widgets/js/widget.js

@@ -62,13 +62,13 b' define(["widgets/js/manager",'
             return Backbone.Model.apply(this);
         },
 
-        send: function (content, callbacks) {
+        send: function (content, callbacks, buffers) {
             /**
              * Send a custom msg over the comm.
              */
             if (this.comm !== undefined) {
                 var data = {method: 'custom', content: content};
-                this.comm.send(data, callbacks);
+                this.comm.send(data, callbacks, {}, buffers);
                 this.pending_msgs++;
             }
         },
@@ -136,12 +136,31 b' define(["widgets/js/manager",'
              * Handle incoming comm msg.
              */
             var method = msg.content.data.method;
+            
             var that = this;
             switch (method) {
                 case 'update':
                     this.state_change = this.state_change
                         .then(function() {
-                            return that.set_state(msg.content.data.state);
+                            var state = msg.content.data.state || {};
+                            var buffer_keys = msg.content.data.buffers || [];
+                            var buffers = msg.buffers || [];
+                            for (var i=0; i<buffer_keys.length; i++) {
+                                state[buffer_keys[i]] = buffers[i];
+                            }
+
+                            // deserialize fields that have custom deserializers
+                            var serializers = that.constructor.serializers;
+                            if (serializers) {
+                                for (var k in state) {
+                                    if (serializers[k] && serializers[k].deserialize) {
+                                        state[k] = (serializers[k].deserialize)(state[k], that);
+                                    }
+                                }
+                            }
+                            return utils.resolve_promises_dict(state);
+                        }).then(function(state) {
+                            return that.set_state(state);
                         }).catch(utils.reject("Couldn't process update msg for model id '" + String(that.id) + "'", true))
                         .then(function() {
                             var parent_id = msg.parent_header.msg_id;
@@ -152,7 +171,7 b' define(["widgets/js/manager",'
                         }).catch(utils.reject("Couldn't resolve state request promise", true));
                     break;
                 case 'custom':
-                    this.trigger('msg:custom', msg.content.data.content);
+                    this.trigger('msg:custom', msg.content.data.content, msg.buffers);
                     break;
                 case 'display':
                     this.state_change = this.state_change.then(function() {
@@ -165,27 +184,23 b' define(["widgets/js/manager",'
         set_state: function (state) {
             var that = this;
             // Handle when a widget is updated via the python side.
-            return this._unpack_models(state).then(function(state) {
+            return new Promise(function(resolve, reject) {
                 that.state_lock = state;
                 try {
                     WidgetModel.__super__.set.call(that, state);
                 } finally {
                     that.state_lock = null;
                 }
+                resolve();
             }).catch(utils.reject("Couldn't set model state", true));
         },
 
         get_state: function() {
             // Get the serializable state of the model.
-            var state = this.toJSON();
-            for (var key in state) {
-                if (state.hasOwnProperty(key)) {
-                    state[key] = this._pack_models(state[key]);
-                }
-            }
-            return state;
+            // Equivalent to Backbone.Model.toJSON()
+            return _.clone(this.attributes);
         },
-
+        
         _handle_status: function (msg, callbacks) {
             /**
              * Handle status msgs.
@@ -243,6 +258,19 b' define(["widgets/js/manager",'
              * Handle sync to the back-end.  Called when a model.save() is called.
              *
              * Make sure a comm exists.
+
+             * Parameters
+             * ----------
+             * method : create, update, patch, delete, read
+             *   create/update always send the full attribute set
+             *   patch - only send attributes listed in options.attrs, and if we are queuing
+             *     up messages, combine with previous messages that have not been sent yet
+             * model : the model we are syncing
+             *   will normally be the same as `this`
+             * options : dict
+             *   the `attrs` key, if it exists, gives an {attr: value} dict that should be synced,
+             *   otherwise, sync all attributes
+             * 
              */
             var error = options.error || function() {
                 console.error('Backbone sync error:', arguments);
@@ -252,8 +280,11 b' define(["widgets/js/manager",'
                 return false;
             }
 
-            // Delete any key value pairs that the back-end already knows about.
-            var attrs = (method === 'patch') ? options.attrs : model.toJSON(options);
+            var attrs = (method === 'patch') ? options.attrs : model.get_state(options);
+
+            // the state_lock lists attributes that are currently be changed right now from a kernel message
+            // we don't want to send these non-changes back to the kernel, so we delete them out of attrs
+            // (but we only delete them if the value hasn't changed from the value stored in the state_lock
             if (this.state_lock !== null) {
                 var keys = Object.keys(this.state_lock);
                 for (var i=0; i<keys.length; i++) {
@@ -263,9 +294,7 b' define(["widgets/js/manager",'
                     }
                 }
             }
-
-            // Only sync if there are attributes to send to the back-end.
-            attrs = this._pack_models(attrs);
+            
             if (_.size(attrs) > 0) {
 
                 // If this message was sent via backbone itself, it will not
@@ -297,8 +326,7 b' define(["widgets/js/manager",'
                 } else {
                     // We haven't exceeded the throttle, send the message like 
                     // normal.
-                    var data = {method: 'backbone', sync_data: attrs};
-                    this.comm.send(data, callbacks);
+                    this.send_sync_message(attrs, callbacks);
                     this.pending_msgs++;
                 }
             }
@@ -308,6 +336,42 b' define(["widgets/js/manager",'
             this._buffered_state_diff = {};
         },
 
+
+        send_sync_message: function(attrs, callbacks) {
+            // prepare and send a comm message syncing attrs
+            var that = this;
+            // first, build a state dictionary with key=the attribute and the value
+            // being the value or the promise of the serialized value
+            var serializers = this.constructor.serializers;
+            if (serializers) {
+                for (k in attrs) {
+                    if (serializers[k] && serializers[k].serialize) {
+                        attrs[k] = (serializers[k].serialize)(attrs[k], this);
+                    }
+                }
+            }
+            utils.resolve_promises_dict(attrs).then(function(state) {
+                // get binary values, then send
+                var keys = Object.keys(state);
+                var buffers = [];
+                var buffer_keys = [];
+                for (var i=0; i<keys.length; i++) {
+                    var key = keys[i];
+                    var value = state[key];
+                    if (value.buffer instanceof ArrayBuffer
+                        || value instanceof ArrayBuffer) {
+                        buffers.push(value);
+                        buffer_keys.push(key);
+                        delete state[key];
+                    }
+                }
+                that.comm.send({method: 'backbone', sync_data: state, buffer_keys: buffer_keys}, callbacks, {}, buffers);
+            }).catch(function(error) {
+                that.pending_msgs--;
+                return (utils.reject("Couldn't send widget sync message", true))(error);
+            });
+        },
+        
         save_changes: function(callbacks) {
             /**
              * Push this model's state to the back-end
@@ -317,61 +381,6 b' define(["widgets/js/manager",'
             this.save(this._buffered_state_diff, {patch: true, callbacks: callbacks});
         },
 
-        _pack_models: function(value) {
-            /**
-             * Replace models with model ids recursively.
-             */
-            var that = this;
-            var packed;
-            if (value instanceof Backbone.Model) {
-                return "IPY_MODEL_" + value.id;
-
-            } else if ($.isArray(value)) {
-                packed = [];
-                _.each(value, function(sub_value, key) {
-                    packed.push(that._pack_models(sub_value));
-                });
-                return packed;
-            } else if (value instanceof Date || value instanceof String) {
-                return value;
-            } else if (value instanceof Object) {
-                packed = {};
-                _.each(value, function(sub_value, key) {
-                    packed[key] = that._pack_models(sub_value);
-                });
-                return packed;
-
-            } else {
-                return value;
-            }
-        },
-
-        _unpack_models: function(value) {
-            /**
-             * Replace model ids with models recursively.
-             */
-            var that = this;
-            var unpacked;
-            if ($.isArray(value)) {
-                unpacked = [];
-                _.each(value, function(sub_value, key) {
-                    unpacked.push(that._unpack_models(sub_value));
-                });
-                return Promise.all(unpacked);
-            } else if (value instanceof Object) {
-                unpacked = {};
-                _.each(value, function(sub_value, key) {
-                    unpacked[key] = that._unpack_models(sub_value);
-                });
-                return utils.resolve_promises_dict(unpacked);
-            } else if (typeof value === 'string' && value.slice(0,10) === "IPY_MODEL_") {
-                // get_model returns a promise already
-                return this.widget_manager.get_model(value.slice(10, value.length));
-            } else {
-                return Promise.resolve(value);
-            }
-        },
-
         on_some_change: function(keys, callback, context) {
             /**
              * on_some_change(["key1", "key2"], foo, context) differs from
@@ -386,7 +395,15 b' define(["widgets/js/manager",'
                 }
             }, this);
 
-       },
+        },
+
+        toJSON: function(options) {
+            /**
+             * Serialize the model.  See the types.js deserialization function
+             * and the kernel-side serializer/deserializer
+             */
+            return "IPY_MODEL_"+this.id;
+        }
     });
     widgetmanager.WidgetManager.register_widget_model('WidgetModel', WidgetModel);
 
@@ -426,7 +443,7 b' define(["widgets/js/manager",'
              */
             var that = this;
             options = $.extend({ parent: this }, options || {});
-            return this.model.widget_manager.create_view(child_model, options).catch(utils.reject("Couldn't create child view"), true);
+            return this.model.widget_manager.create_view(child_model, options).catch(utils.reject("Couldn't create child view", true));
         },
 
         callbacks: function(){
@@ -444,11 +461,11 b' define(["widgets/js/manager",'
              */
         },
 
-        send: function (content) {
+        send: function (content, buffers) {
             /**
              * Send a custom msg associated with this view.
              */
-            this.model.send(content, this.callbacks());
+            this.model.send(content, this.callbacks(), buffers);
         },
 
         touch: function () {
@@ -558,7 +575,7 b' define(["widgets/js/manager",'
             /**
              * Makes browser interpret a numerical string as a pixel value.
              */
-            if (/^\d+\.?(\d+)?$/.test(value.trim())) {
+            if (value && /^\d+\.?(\d+)?$/.test(value.trim())) {
                 return value.trim() + 'px';
             }
             return value;

IPython/html/static/widgets/js/widget_box.js

@@ -4,10 +4,41 b''
 define([
     "widgets/js/widget",
     "jqueryui",
+    "underscore",
     "base/js/utils",
     "bootstrap",
-], function(widget, $, utils){
+], function(widget, $, _, utils){
     "use strict";
+    var unpack_models = function unpack_models(value, model) {
+        /**
+         * Replace model ids with models recursively.
+         */
+        var unpacked;
+        if ($.isArray(value)) {
+            unpacked = [];
+            _.each(value, function(sub_value, key) {
+                unpacked.push(unpack_models(sub_value, model));
+            });
+            return Promise.all(unpacked);
+        } else if (value instanceof Object) {
+            unpacked = {};
+            _.each(value, function(sub_value, key) {
+                unpacked[key] = unpack_models(sub_value, model);
+            });
+            return utils.resolve_promises_dict(unpacked);
+        } else if (typeof value === 'string' && value.slice(0,10) === "IPY_MODEL_") {
+            // get_model returns a promise already
+            return model.widget_manager.get_model(value.slice(10, value.length));
+        } else {
+            return Promise.resolve(value);
+        }
+    };
+
+    var BoxModel = widget.WidgetModel.extend({}, {
+        serializers: _.extend({
+            children: {deserialize: unpack_models}
+        }, widget.WidgetModel.serializers)
+    });
 
     var BoxView = widget.DOMWidgetView.extend({
         initialize: function(){
@@ -148,6 +179,8 b' define(['
     });
 
     return {
+        'unpack_models': unpack_models,
+        'BoxModel': BoxModel,
         'BoxView': BoxView,
         'FlexBoxView': FlexBoxView,
     };

IPython/html/tests/util.js

@@ -337,6 +337,19 b' casper.execute_cell_then = function(index, then_callback, expect_failure) {'
     return return_val;
 };
 
+casper.append_cell_execute_then = function(text, then_callback, expect_failure) {
+    // Append a code cell and execute it, optionally calling a then_callback
+    var c = this.append_cell(text);
+    return this.execute_cell_then(c, then_callback, expect_failure);
+};
+
+casper.assert_output_equals = function(text, output_text, message) {
+    // Append a code cell with the text, then assert the output is equal to output_text
+    this.append_cell_execute_then(text, function(index) {
+        this.test.assertEquals(this.get_output_cell(index).text.trim(), output_text, message);
+    });
+};
+
 casper.wait_for_element = function(index, selector){
     // Utility function that allows us to easily wait for an element 
     // within a cell.  Uses JQuery selector to look for the element.

IPython/html/tests/widgets/widget.js

@@ -40,63 +40,12 b' casper.notebook_test(function () {'
     var index;
 
     index = this.append_cell(
-        'from IPython.html import widgets\n' + 
-        'from IPython.display import display, clear_output\n' +
-        'print("Success")');
+        ['from IPython.html import widgets',
+         'from IPython.display import display, clear_output',
+         'print("Success")'].join('\n'));
     this.execute_cell_then(index);
 
     this.then(function () {
-
-        // Functions that can be used to test the packing and unpacking APIs
-        var that = this;
-        var test_pack = function (input) {
-            var output = that.evaluate(function(input) {
-                var model = new IPython.WidgetModel(IPython.notebook.kernel.widget_manager, undefined);
-                var results = model._pack_models(input);
-                return results;
-            }, {input: input});
-            that.test.assert(recursive_compare(input, output), 
-                JSON.stringify(input) + ' passed through Model._pack_model unchanged');
-        };
-        var test_unpack = function (input) {
-            that.thenEvaluate(function(input) {
-                window.results = undefined;
-                var model = new IPython.WidgetModel(IPython.notebook.kernel.widget_manager, undefined);
-                model._unpack_models(input).then(function(results) { 
-                    window.results = results; 
-                });    
-            }, {input: input});
-            
-            that.waitFor(function check() {
-                return that.evaluate(function() { 
-                    return window.results; 
-                }); 
-            });
-            
-            that.then(function() {
-                var results = that.evaluate(function() { 
-                    return window.results; 
-                });
-                that.test.assert(recursive_compare(input, results), 
-                    JSON.stringify(input) + ' passed through Model._unpack_model unchanged');
-            });
-        };
-        var test_packing = function(input) {
-            test_pack(input);
-            test_unpack(input);
-        };
-        
-        test_packing({0: 'hi', 1: 'bye'});
-        test_packing(['hi', 'bye']);
-        test_packing(['hi', 5]);
-        test_packing(['hi', '5']);
-        test_packing([1.0, 0]);
-        test_packing([1.0, false]);
-        test_packing([1, false]);
-        test_packing([1, false, {a: 'hi'}]);
-        test_packing([1, false, ['hi']]);
-        test_packing([String('hi'), Date("Thu Nov 13 2014 13:46:21 GMT-0500")])
-
         // Test multi-set, single touch code.  First create a custom widget.
         this.thenEvaluate(function() {
             var MultiSetView = IPython.DOMWidgetView.extend({
@@ -113,20 +62,20 b' casper.notebook_test(function () {'
 
     // Try creating the multiset widget, verify that sets the values correctly.
     var multiset = {};
-    multiset.index = this.append_cell(
-        'from IPython.utils.traitlets import Unicode, CInt\n' +
-        'class MultiSetWidget(widgets.Widget):\n' +
-        '    _view_name = Unicode("MultiSetView", sync=True)\n' +
-        '    a = CInt(0, sync=True)\n' +
-        '    b = CInt(0, sync=True)\n' +
-        '    c = CInt(0, sync=True)\n' +
-        '    d = CInt(-1, sync=True)\n' + // See if it sends a full state.
-        '    def set_state(self, sync_data):\n' +
-        '        widgets.Widget.set_state(self, sync_data)\n'+
-        '        self.d = len(sync_data)\n' +
-        'multiset = MultiSetWidget()\n' +
-        'display(multiset)\n' +
-        'print(multiset.model_id)');
+    multiset.index = this.append_cell([
+        'from IPython.utils.traitlets import Unicode, CInt',
+        'class MultiSetWidget(widgets.Widget):',
+        '    _view_name = Unicode("MultiSetView", sync=True)',
+        '    a = CInt(0, sync=True)',
+        '    b = CInt(0, sync=True)',
+        '    c = CInt(0, sync=True)',
+        '    d = CInt(-1, sync=True)', // See if it sends a full state.
+        '    def set_state(self, sync_data):',
+        '        widgets.Widget.set_state(self, sync_data)',
+        '        self.d = len(sync_data)',
+        'multiset = MultiSetWidget()',
+        'display(multiset)',
+        'print(multiset.model_id)'].join('\n'));
     this.execute_cell_then(multiset.index, function(index) {
         multiset.model_id = this.get_output_cell(index).text.trim();
     });
@@ -148,16 +97,16 b' casper.notebook_test(function () {'
     });
 
     var textbox = {};
-    throttle_index = this.append_cell(
-        'import time\n' +
-        'textbox = widgets.Text()\n' +
-        'display(textbox)\n' +
-        'textbox._dom_classes = ["my-throttle-textbox"]\n' +
-        'def handle_change(name, old, new):\n' +
-        '    display(len(new))\n' +
-        '    time.sleep(0.5)\n' +
-        'textbox.on_trait_change(handle_change, "value")\n' +
-        'print(textbox.model_id)');
+    throttle_index = this.append_cell([
+        'import time',
+        'textbox = widgets.Text()',
+        'display(textbox)',
+        'textbox._dom_classes = ["my-throttle-textbox"]',
+        'def handle_change(name, old, new):',
+        '    display(len(new))',
+        '    time.sleep(0.5)',
+        'textbox.on_trait_change(handle_change, "value")',
+        'print(textbox.model_id)'].join('\n'));
     this.execute_cell_then(throttle_index, function(index){
         textbox.model_id = this.get_output_cell(index).text.trim();
 
@@ -169,7 +118,7 b' casper.notebook_test(function () {'
             '.my-throttle-textbox'), 'Textbox exists.');
 
         // Send 20 characters
-        this.sendKeys('.my-throttle-textbox input', '....................');
+        this.sendKeys('.my-throttle-textbox input', '12345678901234567890');
     });
 
     this.wait_for_widget(textbox);
@@ -188,4 +137,173 b' casper.notebook_test(function () {'
         var last_state = outputs[outputs.length-1].data['text/plain'];
         this.test.assertEquals(last_state, "20", "Last state sent when throttling.");
     });
+
+
+    this.thenEvaluate(function() {
+        define('TestWidget', ['widgets/js/widget', 'base/js/utils', 'underscore'], function(widget, utils, _) {
+            var floatArray = {
+                deserialize: function (value, model) {
+                    if (value===null) {return null;}
+                    // DataView -> float64 typed array
+                    return new Float64Array(value.buffer);
+                },
+                // serialization automatically handled since the 
+                // attribute is an ArrayBuffer view
+            };
+            
+            var floatList = {
+                deserialize: function (value, model) {
+                    // list of floats -> list of strings
+                    return value.map(function(x) {return x.toString()});
+                },
+                serialize: function(value, model) {
+                    // list of strings -> list of floats
+                    return value.map(function(x) {return parseFloat(x);})
+                }
+            };
+
+            var TestWidgetModel = widget.WidgetModel.extend({}, {
+                serializers: _.extend({
+                    array_list: floatList,
+                    array_binary: floatArray
+                }, widget.WidgetModel.serializers)
+            });
+            
+            var TestWidgetView = widget.DOMWidgetView.extend({
+                render: function () {
+                    this.listenTo(this.model, 'msg:custom', this.handle_msg);
+                },
+                handle_msg: function(content, buffers) {
+                    this.msg = [content, buffers];
+                }
+            });
+
+            return {TestWidgetModel: TestWidgetModel, TestWidgetView: TestWidgetView};
+        });
+    });
+
+    var testwidget = {};
+    this.append_cell_execute_then([
+        'from IPython.html import widgets',
+        'from IPython.utils.traitlets import Unicode, Instance, List',
+        'from IPython.display import display',
+        'from array import array',
+        'def _array_to_memoryview(x):',
+        '    if x is None: return None',
+        '    try:',
+        '        y = memoryview(x)',
+        '    except TypeError:',
+        '        # in python 2, arrays do not support the new buffer protocol',
+        '        y = memoryview(buffer(x))',
+        '    return y',
+        'def _memoryview_to_array(x):',
+        '    if x is None: return None',
+        '    return array("d", x.tobytes())',
+        'arrays_binary = {',
+        '    "from_json": _memoryview_to_array,',
+        '    "to_json": _array_to_memoryview',
+        '}',
+        '',
+        'def _array_to_list(x):',
+        '    return list(x)',
+        'def _list_to_array(x):',
+        '    return array("d",x)',
+        'arrays_list = {',
+        '    "from_json": _list_to_array,',
+        '    "to_json": _array_to_list',
+        '}',
+        '',
+        'class TestWidget(widgets.DOMWidget):',
+        '    _model_module = Unicode("TestWidget", sync=True)',
+        '    _model_name = Unicode("TestWidgetModel", sync=True)',
+        '    _view_module = Unicode("TestWidget", sync=True)',
+        '    _view_name = Unicode("TestWidgetView", sync=True)',
+        '    array_binary = Instance(array, allow_none=True, sync=True, **arrays_binary)',
+        '    array_list = Instance(array, args=("d", [3.0]), allow_none=False, sync=True, **arrays_list)',
+        '    msg = {}',
+        '    def __init__(self, **kwargs):',
+        '        super(widgets.DOMWidget, self).__init__(**kwargs)',
+        '        self.on_msg(self._msg)',
+        '    def _msg(self, _, content, buffers):',
+        '        self.msg = [content, buffers]',
+        'x=TestWidget()',
+        'display(x)',
+        'print(x.model_id)'].join('\n'), function(index){
+            testwidget.index = index;
+            testwidget.model_id = this.get_output_cell(index).text.trim();
+        });
+    this.wait_for_widget(testwidget);
+
+
+    this.append_cell_execute_then('x.array_list = array("d", [1.5, 2.0, 3.1])');
+    this.wait_for_widget(testwidget);
+    this.then(function() {
+        var result = this.evaluate(function(index) {
+            var v = IPython.notebook.get_cell(index).widget_views[0];
+            var result = v.model.get('array_list');
+            var z = result.slice();
+            z[0]+="1234";
+            z[1]+="5678";
+            v.model.set('array_list', z);
+            v.touch();
+            return result;
+        }, testwidget.index);
+        this.test.assertEquals(result, ["1.5", "2", "3.1"], "JSON custom serializer kernel -> js");
+    });
+    
+    this.assert_output_equals('print(x.array_list.tolist() == [1.51234, 25678.0, 3.1])',
+                              'True', 'JSON custom serializer js -> kernel');
+
+    if (this.slimerjs) {
+        this.append_cell_execute_then("x.array_binary=array('d', [1.5,2.5,5])", function() {
+            this.evaluate(function(index) {
+                var v = IPython.notebook.get_cell(index).widget_views[0];
+                var z = v.model.get('array_binary');
+                z[0]*=3;
+                z[1]*=3;
+                z[2]*=3;
+                // we set to null so that we recognize the change
+                // when we set data back to z
+                v.model.set('array_binary', null);
+                v.model.set('array_binary', z);
+                v.touch();
+            }, textwidget.index);
+        });
+        this.wait_for_widget(testwidget);
+        this.assert_output_equals('x.array_binary.tolist() == [4.5, 7.5, 15.0]',
+                                  'True\n', 'Binary custom serializer js -> kernel')
+
+        this.append_cell_execute_then('x.send("some content", [memoryview(b"binarycontent"), memoryview("morecontent")])');
+        this.wait_for_widget(testwidget);
+
+        this.then(function() {
+            var result = this.evaluate(function(index) {
+                var v = IPython.notebook.get_cell(index).widget_views[0];
+                var d = new TextDecoder('utf-8');
+                return {text: v.msg[0], 
+                        binary0: d.decode(v.msg[1][0]),
+                        binary1: d.decode(v.msg[1][1])};
+            }, testwidget.index);
+            this.test.assertEquals(result, {text: 'some content', 
+                                       binary0: 'binarycontent', 
+                                       binary1: 'morecontent'}, 
+                              "Binary widget messages kernel -> js");
+        });
+
+        this.then(function() {
+            this.evaluate(function(index) {
+                var v = IPython.notebook.get_cell(index).widget_views[0];
+                v.send('content back', [new Uint8Array([1,2,3,4]), new Float64Array([2.1828, 3.14159])])
+            }, testwidget.index);
+        });
+        this.wait_for_widget(testwidget);
+        this.assert_output_equals([
+            'all([x.msg[0] == "content back",',
+            '     x.msg[1][0].tolist() == [1,2,3,4],',
+            '     array("d", x.msg[1][1].tobytes()).tolist() == [2.1828, 3.14159]])'].join('\n'),
+                                  'True', 'Binary buffers message js -> kernel');
+    } else {
+        console.log("skipping binary websocket tests on phantomjs");
+    }
+
 });

IPython/html/widgets/widget.py

@@ -216,10 +216,11 b' class Widget(LoggingConfigurable):'
         key : unicode, or iterable (optional)
             A single property's name or iterable of property names to sync with the front-end.
         """
-        self._send({
-            "method" : "update",
-            "state"  : self.get_state(key=key)
-        })
+        state, buffer_keys, buffers = self.get_state(key=key)
+        msg = {"method": "update", "state": state}
+        if buffer_keys:
+            msg['buffers'] = buffer_keys
+        self._send(msg, buffers=buffers)
 
     def get_state(self, key=None):
         """Gets the widget state, or a piece of it.
@@ -228,6 +229,16 b' class Widget(LoggingConfigurable):'
         ----------
         key : unicode or iterable (optional)
             A single property's name or iterable of property names to get.
+
+        Returns
+        -------
+        state : dict of states
+        buffer_keys : list of strings
+            the values that are stored in buffers
+        buffers : list of binary memoryviews
+            values to transmit in binary
+        metadata : dict
+            metadata for each field: {key: metadata}
         """
         if key is None:
             keys = self.keys
@@ -238,11 +249,18 b' class Widget(LoggingConfigurable):'
         else:
             raise ValueError("key must be a string, an iterable of keys, or None")
         state = {}
+        buffers = []
+        buffer_keys = []
         for k in keys:
             f = self.trait_metadata(k, 'to_json', self._trait_to_json)
             value = getattr(self, k)
-            state[k] = f(value)
-        return state
+            serialized = f(value)
+            if isinstance(serialized, memoryview):
+                buffers.append(serialized)
+                buffer_keys.append(k)
+            else:
+                state[k] = serialized
+        return state, buffer_keys, buffers
 
     def set_state(self, sync_data):
         """Called when a state is received from the front-end."""
@@ -253,15 +271,17 b' class Widget(LoggingConfigurable):'
                 with self._lock_property(name, json_value):
                     setattr(self, name, from_json(json_value))
     
-    def send(self, content):
+    def send(self, content, buffers=None):
         """Sends a custom msg to the widget model in the front-end.
 
         Parameters
         ----------
         content : dict
             Content of the message to send.
+        buffers : list of binary buffers
+            Binary buffers to send with message
         """
-        self._send({"method": "custom", "content": content})
+        self._send({"method": "custom", "content": content}, buffers=buffers)
 
     def on_msg(self, callback, remove=False):
         """(Un)Register a custom msg receive callback.
@@ -269,9 +289,9 b' class Widget(LoggingConfigurable):'
         Parameters
         ----------
         callback: callable
-            callback will be passed two arguments when a message arrives::
+            callback will be passed three arguments when a message arrives::
             
-                callback(widget, content)
+                callback(widget, content, buffers)
             
         remove: bool
             True if the callback should be unregistered."""
@@ -353,7 +373,10 b' class Widget(LoggingConfigurable):'
         # Handle backbone sync methods CREATE, PATCH, and UPDATE all in one.
         if method == 'backbone':
             if 'sync_data' in data:
+                # get binary buffers too
                 sync_data = data['sync_data']
+                for i,k in enumerate(data.get('buffer_keys', [])):
+                    sync_data[k] = msg['buffers'][i]
                 self.set_state(sync_data) # handles all methods
 
         # Handle a state request.
@@ -363,15 +386,15 b' class Widget(LoggingConfigurable):'
         # Handle a custom msg from the front-end.
         elif method == 'custom':
             if 'content' in data:
-                self._handle_custom_msg(data['content'])
+                self._handle_custom_msg(data['content'], msg['buffers'])
 
         # Catch remainder.
         else:
             self.log.error('Unknown front-end to back-end widget msg with method "%s"' % method)
 
-    def _handle_custom_msg(self, content):
+    def _handle_custom_msg(self, content, buffers):
         """Called when a custom msg is received."""
-        self._msg_callbacks(self, content)
+        self._msg_callbacks(self, content, buffers)
 
     def _notify_trait(self, name, old_value, new_value):
         """Called when a property has been changed."""
@@ -393,35 +416,12 b' class Widget(LoggingConfigurable):'
         self._display_callbacks(self, **kwargs)
 
     def _trait_to_json(self, x):
-        """Convert a trait value to json
-
-        Traverse lists/tuples and dicts and serialize their values as well.
-        Replace any widgets with their model_id
-        """
-        if isinstance(x, dict):
-            return {k: self._trait_to_json(v) for k, v in x.items()}
-        elif isinstance(x, (list, tuple)):
-            return [self._trait_to_json(v) for v in x]
-        elif isinstance(x, Widget):
-            return "IPY_MODEL_" + x.model_id
-        else:
-            return x # Value must be JSON-able
+        """Convert a trait value to json."""
+        return x
 
     def _trait_from_json(self, x):
-        """Convert json values to objects
-
-        Replace any strings representing valid model id values to Widget references.
-        """
-        if isinstance(x, dict):
-            return {k: self._trait_from_json(v) for k, v in x.items()}
-        elif isinstance(x, (list, tuple)):
-            return [self._trait_from_json(v) for v in x]
-        elif isinstance(x, string_types) and x.startswith('IPY_MODEL_') and x[10:] in Widget.widgets:
-            # we want to support having child widgets at any level in a hierarchy
-            # trusting that a widget UUID will not appear out in the wild
-            return Widget.widgets[x[10:]]
-        else:
-            return x
+        """Convert json values to objects."""
+        return x
 
     def _ipython_display_(self, **kwargs):
         """Called when `IPython.display.display` is called on the widget."""
@@ -430,9 +430,9 b' class Widget(LoggingConfigurable):'
             self._send({"method": "display"})
             self._handle_displayed(**kwargs)
 
-    def _send(self, msg):
+    def _send(self, msg, buffers=None):
         """Sends a message to the model in the front-end."""
-        self.comm.send(msg)
+        self.comm.send(data=msg, buffers=buffers)
 
 
 class DOMWidget(Widget):

IPython/html/widgets/widget_box.py

@@ -6,19 +6,46 b' Represents a container that can be used to group other widgets.'
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from .widget import DOMWidget, register
+from .widget import DOMWidget, Widget, register
 from IPython.utils.traitlets import Unicode, Tuple, TraitError, Int, CaselessStrEnum
 from IPython.utils.warn import DeprecatedClass
 
+def _widget_to_json(x):
+    if isinstance(x, dict):
+        return {k: _widget_to_json(v) for k, v in x.items()}
+    elif isinstance(x, (list, tuple)):
+        return [_widget_to_json(v) for v in x]
+    elif isinstance(x, Widget):
+        return "IPY_MODEL_" + x.model_id
+    else:
+        return x
+
+def _json_to_widget(x):
+    if isinstance(x, dict):
+        return {k: _json_to_widget(v) for k, v in x.items()}
+    elif isinstance(x, (list, tuple)):
+        return [_json_to_widget(v) for v in x]
+    elif isinstance(x, string_types) and x.startswith('IPY_MODEL_') and x[10:] in Widget.widgets:
+        return Widget.widgets[x[10:]]
+    else:
+        return x
+
+widget_serialization = {
+    'from_json': _json_to_widget,
+    'to_json': _widget_to_json
+}
+
+
 @register('IPython.Box')
 class Box(DOMWidget):
     """Displays multiple widgets in a group."""
+    _model_name = Unicode('BoxModel', sync=True)
     _view_name = Unicode('BoxView', sync=True)
 
     # Child widgets in the container.
     # Using a tuple here to force reassignment to update the list.
     # When a proper notifying-list trait exists, that is what should be used here.
-    children = Tuple(sync=True)
+    children = Tuple(sync=True, **widget_serialization)
     
     _overflow_values = ['visible', 'hidden', 'scroll', 'auto', 'initial', 'inherit', '']
     overflow_x = CaselessStrEnum(

IPython/html/widgets/widget_button.py

@@ -67,7 +67,7 b' class Button(DOMWidget):'
             Set to true to remove the callback from the list of callbacks."""
         self._click_handlers.register_callback(callback, remove=remove)
 
-    def _handle_button_msg(self, _, content):
+    def _handle_button_msg(self, _, content, buffers):
         """Handle a msg from the front-end.
 
         Parameters