Sunday, 07 July 2013 - Nesterovsky bros

Sunday, 07 July 2013

Earlier, in the article How To: Load KendoUI Templates from External Files, we were talking about the way to combine project's templates into a single file using Text Templates. Now, we would like to suggest the next step.

KendoUI defines text templates that it knows to transform into functions, at runtime obviously. Thus a template like this:

<tr> <td data-bind=" text: name"></td> <td>#: kendo.toString(get("price"), "C") #</td> <td data-bind="text: unitsInStock"></td> <td><button class="k-button" data-bind="click: deleteProduct"> Delete</button></td> </tr>

is transformed into a function:

function(data) { var o,e=kendo.htmlEncode; with(data) { o='<tr><td data-bind="text: name"></td><td>'+ e( kendo.toString(get("price"), "C") )+ '</td><td data-bind="text: unitsInStock"></td>' + '<td><button class="k-button" ' + 'data-bind="click: deleteProduct">Delete</button></td></tr>'; } return o; }

The transformation is done through a sequence of of regex replaces.

Now, what's the fastest javascript template engine?

Right! That, which does not work at runtime. :-)

What we thought is that we can generate those functions at compile time rather than defining templates.

We have updated templates.tt to generate template functions, and optionally to generate <script> tags that call those functions. This way, for an input footer.tmpl.html:

<!DOCTYPE html> <html> <head> <title>Test</title> <base href="/" /> <link href="styles/kendo.common.min.css" rel="stylesheet" /> <link href="styles/kendo.default.min.css" rel="stylesheet" /> </head> <body> <table data-template-id="view"> <tr> <td>Products count: #: total() #</td> <td>Total price: #: totalPrice() #</td> <td colspan="2">Units in stock: #: totalUnitsInStock() #</td> </tr> </table> </body> </html>

templates.js will look like this:

nesterovskyBros.templates= { ... "footer-view":function(data) { var o,e=kendo.htmlEncode; with(data) { ... } return o; }, ... }; document.write('<script id="footer-view-template" type="text/x-kendo-template">#=nesterovskyBros.templates["footer-view"](data)#</script>');

To get template function at runtime you simply refer to nesterovskyBros.templates["footer-view"].

template.tt now allows you to specify:

scope - a javascript scope for tempate functions, e.g. "nesterovskyBros.templates";
data-script attribute over each template (default is true) to prevent generation of <script> tag;
data-with-block attribute (default is true) to prevent with(data) {...} statement in javascript.

See a sample application that shows how nicely KendoUI UserControls work with those compiled templates.

Sunday, 07 July 2013 18:54:57 UTC

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javascript | kendoui | Thinking aloud

Wednesday, 03 July 2013

Derived xml schemas

Awhile ago we have created a set of xml schemas and xslt to represent different languages as xml, and to generate source from those xmls. This way we know to represent and generate: java, c#, cobol, and several sql dialects (read about languages xom on this site).

Here, we'd like to expose a nuisance we had with sql dialects schema.

Our goal was to define a basic sql schema, and dialect extensions. This way we assumed to express general and dialect specific constructs. So, lets consider an example.

General:

-- Select one row select * from A

DB2:

select * from A fetch first row only

T-SQL:

select top 1 * from A

Oracle:

select * from A where rownum = 1

All these queries have common core syntax, while at the same time have dialect specific means to express intention to return first row only.

Down to the xml schema basic select statement looks like this:

<xs:complexType name="select-statement"> <xs:complexContent> <xs:extension base="full-select-statement"> <xs:sequence> <xs:element name="columns" type="columns-clause"> <xs:element name="from" type="from-clause" minOccurs="0"> <xs:element name="where" type="unary-expression" minOccurs="0"/> <xs:element name="group-by" type="expression-list" minOccurs="0"/> <xs:element name="having" type="unary-expression" minOccurs="0"/> <xs:element name="order-by" type="order-by-clause" minOccurs="0"/> </xs:sequence> <xs:attribute name="specification" type="query-specification" use="optional" default="all"/> </xs:extension> </xs:complexContent> </xs:complexType>

Here all is relatively clear. The generic select looks like:

<sql:select> <sql:columns> <sql:column wildcard="true"/> </sql:columns> <sql:from> <sql:table name="A"/> </sql:from> </sql:select>

But how would you define dialect specifics?

E.g. for T-SQL we would like to see a markup:

<sql:select> <tsql:top> <sql:number value="1"/> </tsql:top> <sql:columns> <sql:column wildcard="true"/> </sql:columns> <sql:from> <sql:table name="A"/> </sql:from> </sql:select>

While for DB2 there should be:

<sql:select> <sql:columns> <sql:column wildcard="true"/> </sql:columns> <sql:from> <sql:table name="A"/> </sql:from> <db2:fetch-first rows="1"/> </sql:select>

So, again the quesions are:

how to define basic sql schema with goal to extend it in direction of DB2 or T-SQL?
how to define an xslt sql serializer that will be also extendable?

Though we have tried several solutions to that problem, none is satisfactory enough. To allow extensions we have defined that all elements in sql schema are based on sql-element, which allows extensions:

<xs:complexType name="sql-element" abstract="true"> <xs:sequence> <xs:element ref="extension" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> <xs:element name="extension" type="extension"/> <xs:complexType name="extension" abstract="true"> <xs:complexContent> <xs:extension base="sql-element"/> </xs:complexContent> </xs:complexType> ... <xs:element name="top" type="top-extension" substitutionGroup="sql:extension"/> <xs:complexType name="top-extension"> <xs:complexContent> <xs:extension base="sql:extension"> <xs:sequence> <xs:element ref="sql:expression"/> </xs:sequence> <xs:attribute name="percent" type="xs:boolean" use="optional" default="false"/> </xs:extension> </xs:complexContent> </xs:complexType>

Unfortunately, this creates too weak typed schema for extensions, thus intellisence suggests too many options.

Wednesday, 03 July 2013 05:50:43 UTC

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Thinking aloud | xslt

Wednesday, 26 June 2013

A bit of science fiction?

On a way to a home we usually listen audio books in our car. In most cases these are science fiction stories. One of our favorite authors is Ray Bradbury. Probably you know his short story collection "The Martian Chronicles". Also, we like to glance over technology and science news to stay tuned in the latest innovations.

Recently, we've read an article that states that NASA is going to send a group of scientists-colonists to Mars in an observable future. It sounds in Ray Bradbury style.

Although, we're not specialists in this field, we discussed what difficulties may face such an expedition.

As far as we understand, there are following issues that must be solved before expedition may start:

speed of a spaceship is yet too slow
a shield from radiation doesn't exist
big cargo section to contain sufficient reserve of water, food and oxygen for the expedition to survive
a way to produce enough energy to survive on Mars

Actually, the second issue depends on the first one. At present there is no reliable long term protection from cosmic radiation, which can be installed on a spacecraft. At least we didn't hear about such thing. Thus, long staying in the open space will seriously harm colonists and may bring to naught the whole mission.

Сonsidering these facts, we concluded that a space travel further than the moon is not possible at present.

What could be done to solve these issues?

As a solution of space colonization could be the following. The earthlings won't send people but robots with corresponding equipment and containers for man, animals and plants DNAs or embryos. At the destination place robots will build a colony and will begin to grow people, animals, plants; to train them and to serve them later (at least to man <img alt= " src="http://www.nesterovsky-bros.com/weblog/smilies/wink.gif"/> ).

How all this may solve the mentioned issues?

It's much easier to create reliable shield from radiation for small DNA or embrios containers.
time and speed of a spacecraft, in such case, will impact less on the mission.
weight of spacecraft in this case could be less, or it may get more payload.

Thus, to bring the era of cosmic expansion, human kind must invest in the development of robotics, artificial intelligence, genetic engineering, development of rapid learning, among other scientific fields in space exploration.

Right now, you may see a beginning? of this trend in sciense here DFKI's robot ape to colonize the Moon?

In the far future, after the beginning will be forgotten, all this may lead to question: who was the first a man or a robot? <img alt= " src="http://www.nesterovsky-bros.com/weblog/smilies/wink.gif"/>

Wednesday, 26 June 2013 20:23:35 UTC

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Thinking aloud

Tuesday, 28 May 2013

Kendo progress utility

While developing with KendoUI we have found kendo.ui.progress(container, toggle) function to be very useful. It's used to show or hide a progress indicator in the container element.

At the same time we have found that we usually used it in a context of async operation. This way, we want to show progress, perform some asynchronous operations, hide progress. So, we clearly want to benifit from RAII pattern: we would like to open a progress scope, and to perform some activity withing this scope.

Arguing like this, we have defined a utility function, which is the fusion of kendo.ui.progress() and $.when(). Its signature is like this:

nesterovskyBros.progress = function(instance /*, task ... */)

where instance is either Model, Widget, JQuery or DOM Element, and task is one or more deferred objects. This function shows a progress and returns a Promise that will hide a progress when all tasks will be complete. Implementation is trivial, so we quote it here:

// Fusion of kendo.ui.progress() and $.when(). scope.progress = function(instance /*, task ... */) { if (instance instanceof Model) { instance = instance.owner && instance.owner(); } if (instance instanceof Widget) { instance = instance.element; } if (instance && instance.nodeType) { instance = $(instance); } var id = ns + "-progress"; // "nesterovskyBros-progress"; var progress = (instance && instance.data(id)) || 0; if (arguments.length < 2) { return progress; } var result = $.when.apply(null, [].slice.call(arguments, 1)); if (instance) { instance.data(id, ++progress); kendo.ui.progress(instance, progress > 0); result.always( function() { progress = instance.data(id) || 0; instance.data(id, --progress); kendo.ui.progress(instance, progress > 0); }); } return result; };

The use is like this:

nesterovskyBros.progress(element, $.ajax("/service1"), $.ajax("/service2")).then(myFunc);

The code can be found at controls.js.

Tuesday, 28 May 2013 05:54:52 UTC

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javascript | kendoui | Tips and tricks

Saturday, 18 May 2013

KendoUI controls.js

While trying to generalize our practices from KendoUI related projects we've participated so far, we updated control.js - a small javascript additions to KendoUI.

At present we have defined:

1. An extended model. See KendoUI extended model.

2. A lightweight user control - a widget to bind a template and a model, and to facilitate declarative instantiation. See KendoUI User control.

3. A reworked version of nesterovskyBros.defineControl() function.

var widgetType = scope.defineControl( { name: widget-name-string, model: widget-model-type, template: optional-content-template, windowOptions: optional-window-options }, base);

When optional-content-template is not specified then template is calculated as following:

var template = options.temlate || proto.template || model.temlate; if (template === undefined) { template = scope.template(options.name.toLowerCase() + "-template"); }

When windowOptions is specified then widgetType.dialog(options) function is defined. It's used to open dialog based on the specified user control. windowOptions is passed to kendo.ui.Window constructor. windowOptions.closeOnEscape indicates whether to close opened dialog on escape.

widgetType.dialog() returns a kendo.ui.Window instance with content based on the user control. Window instance contains functions:

result() - a $.Deffered for the dialog result, and
model() - referring to the user control model.

The model instance has functions:

dialog() referring to the dialog, and
result() referring to the dialog result.

widget.dialog() allows all css units in windowOptions.width and windowOptions.height parameters.

base - is optional user control base. It defaults to nesterovskyBros.ui.UserControl.

4. Adjusted splitter. See Adjust KendoUI Splitter.

5. Auto resize support.

Layout is often depends on available area. One example is Splitter widget that recalculates its panes when window or container Splitter is resized. There are other cases when you would like to adjust layout when a container's area is changed like: adjust grid, tab, editor or user's control contents.

KendoUI does not provide a solution for this problem, so we have defined our own.

A widget can be marked with class="auto-resize" marker;
A widget may define a widgetType.autoResize(element) function that adapts widget to a new size.
A code can call nesterovskyBros.resize(element) function at trigger resizing of the subtree.

To support existing controls we have defined autoResize() function for Grid, Splitter, TabStrip, and Editor widgets.

To see how auto resizing works, it's best to look into index.html, products.tmpl.html, and into the implementation controls.js.

Please note that we consider controls.js as an addition to KendoUI library. If in the future the library will integrate or implement similar features we will be happy to start using their API.

Extensions in `nesterovskyBros.data.Model`

As with kendo.data.Model there is fields Object - a set of key/value pairs to configure the model fields, but fields have some more options:
- fields.fieldName.serializable Boolean - indicates whether the field appears in an object returned in model.toJSON(). Default is true.
- fields.fieldName.updateDirty Boolean - indicates whether the change of the property should trigger dirty field change. Default is true.
When model defines a field and there is a prototype function with the same name then this function is used to get and set a field value.
When property is changed through the model.set() method then dirty change event is triggered (provided that fields.fieldName.updateDirty !== false). This helps to build a dependcy graph on that property.
When model instance is consturcted, the data passed in are validated, nullable and default values are set.

Model example

Here is an example of a model:

nesterovskyBros.data.ProductModel = nesterovskyBros.data.Model.define( { fields: { name: { type: "string", defaultValue: "Product Name" }, price: { type: "number", defaultValue: 10 }, unitsInStockValue: { type: "number", defaultValue: 10, serializable: false }, unitsInStock: { type: "string" } }, unitsInStock: function(value) { if (value === undefined) { var count = this.get("unitsInStockValue"); return ["one", "two", "three", "four"][count] || (count + ""); } else { this.set("unitsInStockValue", ({one: 1, two: 2, three: 3, four: 4 })[value] || value); } } });

Notice that:

unitsInStock property is implemented as a function - this helps to map model values to presentation values.
when you call model.toJSON(), or JSON.stringify() you will see in result name, price, unitsInStock values only - this helps to get model's state and to store it somewhere (e.g. in sessionStorage).
in a code:
var model = new nesterovskyBros.data.ProductModel({ price: "7", unitsInStock: "one" });
the following is true:
(typeof(model.price) == "number") && (mode.price == 7) && (model.name == "Product Name") && (model.unitsInStockValue == 1)

As with UserControl the implemntation is defined in the controls.js. The sample page is the same index.html

Wednesday, 03 April 2013 20:37:49 UTC

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javascript | Thinking aloud | Tips and tricks

Thursday, 28 March 2013

Windows 8 + Lenovo Yoga-13 + external SD card

Two weeks ago we've gotten new Lenovo 13" laptops (Yoga-13 with touch screens and Windows 8 Pro on board).

The first expression was WOW! Touch screens! Windows 8! Now we'll try our hand on that new (for us) API. So new, so cool...

A day later. What a shit this new UI. Where are my desktop, "Start" button, all the programs... After googling we've understood - we're not alone.

Few more days later. We've recognized that our SSD hard disk won't live long life with our projects. We generates output several GB a day. Thus we've decided to buy external SD cards - additional 64Gb, class 10. That's enough for us. No sooner said than done. After several attempts to copy our projects from hard drive to SD card (~9Gb of sources) we strongly believe that such a vigorous mix (Lenovo + Win 8 + external SD card) won't survive. Windows 8 hangs up when display off (in middle of data copy, after an hour of work). What a .... of .... this Windows 8, Lenovo and SD cards all together.

Thursday, 28 March 2013 22:39:55 UTC

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Thinking aloud

Tuesday, 26 March 2013

KendoUI User control

Developing with KendoUI we try to formalize tasks. With this in mind we would like to have user controls.

We define user control as following:

It is a javascript class that extends Widget.
It offers a way to reuse UI.
It allows to define a model and a template with UI and data binding.

Unfortunately, KendoUI does not have such API, though one can easily define it; so we have defined our version.

Here we review our solution. We have taken a grid KendoUI example and converted it into a user control.

User control on the page

See index.html

<!DOCTYPE html> <html> <head> <title>Test</title>  <script src="scripts/templates.js"></script> <script src="scripts/jquery/jquery.js"></script> <script src="scripts/kendo/kendo.web.min.js"></script>  <script src="scripts/controls.js"></script>  <script src="scripts/controls/confirm.js"></script>  <script src="scripts/controls/products.js"></script> <link href="styles/kendo.common.min.css" rel="stylesheet" /> <link href="styles/kendo.default.min.css" rel="stylesheet" /> <script> $(function () { // (5) Bind the page. kendo.bind( document.body, // (6) Model as a datasource. { source: [new nesterovskyBros.data.ProductsModel] }); }); </script> </head> <body>  <div data-role="products" data-bind="source: source"></div> </body> </html>

That's what we see here:

Templates that define layouts. See "How To: Load KendoUI Templates from External Files", and templates.tt.
Definition of the UserControl widget.
Confirm dialog user control (we shall mention it later).
Products user control.
Data binding that instantiates page controls.
Model is passed to a user control through the dataSource.
Use of Products user control. Notice that "data-role" defines control type, "source" refers to the model.

User Control declaration

Declaration consists of a view and a model.

View is html with data binding. See products.tmpl.html

We build our project using Visual Studio, so templates packaging is done with templates.tt. This transformation converts products template into a tag:

<script id="products-template" type="text/x-kendo-template">

thus template can be referred by a utility function: nesterovskyBros.template("products-template").

Model inherits kedo.data.Model. Here how it looks:

// (1) Define a ProducsModel class. nesterovskyBros.data.ProductsModel = kendo.data.Model.define( { // (2) Model properties. fields: { productName: { type: "string", defaultValue: "Product Name" }, productPrice: { type: "number", defaultValue: 10 }, productUnitsInStock: { type: "number", defaultValue: 10 }, products: { type: "default", defaultValue: [] } }, // (3) Model methods. addProduct: function () { ... }, deleteProduct: function (e) { ... }, ... }); // (4) Register user control. nesterovskyBros.ui.Products = nesterovskyBros.defineControl( { name: "Products", model: nesterovskyBros.data.ProductsModel });

That's what we have here:

We define a model that inherits KendoUI Model.
We define model fields.
We define model methods.
Register user control with nesterovskyBros.defineControl(proto) call, where:
- proto.name - defines user control name;
- proto.model - defines model type;
- proto.template - defines optional template. If not specified, a template is retrieved from $("#" + proto.name.toLowerCase() + "-template").html().

UserControl API

Now, what's remained is API for the UserControl. See controls.js.

UserControl defines following events:
- change - triggered when data source is changed;
- dataBound - triggered when widget is data bound;
- dataBinding - triggered befor widget data binding;
- save - used to notify user to save model state.
UserControl defines following options:
- autoBind (default false) - autoBind data source;
- template (default $.noop) - user control template.
UserControl defines dataSource field and setDataSource() method.
UserControl defines rebind() method to manually rebuild widget's view from the template and model.
UserControl sets/deletes model.owner, which is a function returning a user control widget when model is bound/unbound to the widget.
When UserControl binds/unbinds model a model.refresh method is called, if any.
You usually define you control with a call nesterovskyBros.defineControl(proto). See above.
There is also a convenience method to build a dialog based on a user control: nesterovskyBros.defineDialog(options), where
- options.name - a user control name (used in the data-role);
- options.model - a model type;
- options.windowOptions - a window options.
This method returns a function that recieves a user control model, and returns a dialog (kendo.ui.Window) based on the user control.
Dialog has model() function that returns an instance of model.
Model has dialog() function that returns an instance of the dialog.
Dialog and model have result() function that returns an instance of deferred object used to track dialog completion.
The example of user control dialog is confirm.js and confirm.tmpl.html. The use is in the products.js deleteProduct():

deleteProduct: function(e) { var that = this; return nesterovskyBros.dialog.confirm( { title: "Please confirm", message: "Do you want to delete the record?", confirm: "Yes", cancel: "No" }). open(). center(). result(). then( function(confirmed) { if (!confirmed) { return; } ... }); }

Last

User controls along with technique to manage and cache templates allow us to build robust web applications. As the added value it's became a trivial task to build SPA.

Extensions in nesterovskyBros.data.Model