WinJS at NYC Code Camp 2012

Introduction to WinJSDmitri Artamonov

BlueMetal Architectsdmitria@bluemetal.com

#dartamon

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Agenda

Switching from C# What is WinJS? What’s under the hood? Where does WinJS fit? What’s new in WinJS? Patterns and Practices Managing WinJS on the Enterprise Testing WinJS for Store Submission

What I will not talk about

Tiles and Notifications Content before Chrome Sensors/NFC Contracts/Charms New Controls Process Lifecycle Management Triggers/Background Tasks Etc…

Switching from C#/XAML to WinJS

Difference in thinking – advantages of HTML5 over XAML XAML -> HTML5/CSS3 C#/CLR -> Javascript/WinJS Code Organization MVVM -> MVC Available Tools Is C# now obsolete?

What is WinJS?

A standard library to access native Windows 8 functionality through Javascript and HTML5

Fully HTML5-compliant Uses attributes to add new Windows 8 functionality to standard

HTML5 code Accessed as a standard object in Javascript

What’s under the hood?

Language projections Web hardware-accelerated rendering and Javascript interpretation

technology originally started with IE9 (HTML5 compliant) Connects to the same .winmd components as the C#/XAML Windows

8 applications Chakra JScript engine has its peculiarities – garbage collection is done

at the end of script execution, can use up a lot of memory Will WinJS evolve away from IE roots?

Under the hood (cont’d)

Chakra engine for Javascript interpretation

Where does WinJS fit?

Rapid development, friendly to web developers Performance can be slower than other languages, may improve in the

future Can fully interface with components written in other languages More maintainable by enterprises with web developer staff Development can be less frustrating and cheaper if you take

advantage of libraries and resources already available to JS developers Lower costs and faster workflow – designers can work with HTML

directly

Other JS Libraries

jQuery Graphing (HighCharts or Raphael) MVC libraries You can create applications without using WinJS at all!

What’s new?

Page Structure/Navigation Promises Cloud Integration Contracts Tiles and Notifications Speech Integration

Page Structure and Navigation in WinJS Similar to the browser – HTML file that references JS files PageControlNavigator out of the box Navigation back stack Standard Project Template Demo

Promises

Async pattern implemented in javascript, similar to try-catch-finally

WinJS.xhr({ url: urlString, responseType: "json" }).then( function handleResponse(result) { // Handle the returned data },

function handleException(exception) {// Handle return exception

} ).done(function afterResponse() {

// Handle code to be executed once xhr returns});

Cloud integration

File Picker APIs – saving to the cloud and loading from the cloud – allows us to expose the cloud as part of the file system

File Picker APIs – exposes a custom UI that allows users to pick files to open or a location to save - hosted view activation.

File Picker APIs – what constitutes a file is up to you – aggregation? Roaming API – saving data in the cloud that is associated with your

profile Roaming API - creating an experience, not just one app on one machine SkyDrive Demo

Patterns and Practices

MVC? Regions Combining WinJS with C# via .winmd components Modules and Dependency Injection Dynamic code loading (requires disabling security)

MVVM

There were problems with MVVM Lack of controllers in classic MVVM, debate between heavy VMs and

use of controllers Dedicated classes to store information for presentation With XAML, only one DataContext per view Can’t be directly transitioned to WinJS – absence of two-way bindings,

multiple data contexts per view

MVC on WinJS

Where do we move from MVVM? Is MVVM dead? Current limitation: no two-way binding in WinJS Have to trap user input and respond to it Trapping can be done via a controller, get rid of classic MVVM Application/Domain Model conversion can be done via regions Use defined namespaces and classes to create observable objects;

ways to make objects observable are also available

Regions

Using the magic of WinJS we can bind elements to objects, thus setting their datacontext

Two ways we can do the binding: data-win-bind and data-win-bindsource

data-win-bind is used for binding a single field to the data contextHTML5:<span data-win-bind=“innerText: dto.title”></span>JS:WinJS.Binding.processAll(target element, data context object)

Regions (cont’d)

data-win-bindsource allows to set the data context for an element declaratively instead of calling WinJS.Binding.processAll() in Javascript

<div data-win-bindsource=“dto"> Allows for more binding code to be moved into HTML5

Using .winmd components

You can create your own .winmd components in other languages that your app can interface with, the same way it does with WinJS

Take advantage of performance or library disparities – different components are implemented differently

Modules and dependency injection

Javascript was born from simple scripting Modern applications require maintainable, testable code with private scope A module is an anonymous, self-executing function with parameters for

dependency injection:

(function (internalParam1, internalParam2) {"use strict";// private code goes here

})(globalParam1, globalParam2);

Modules and namespaces

Exposing endpoints for public access from the module via classes and namespaces:

WinJS.Namespace.define("ClassicCars", {FindCars: _findCars(), // can define members in namespacesRepairBills: WinJS.Class.define(function(quantity) { // constructor code goes here },{ GetCost: _getCost }, // instance members{ repairBillTypes: [ “S", “U" ] }) // static members

});

Dynamic code loading

What if we could update the application dynamically, without having to re-distribute it?

Can download HTML/JS code via iframe (security enabled, features disabled)

Fragments API – able to load in HTML content from external web sources into the application

Can download code directly into the app (requires unsecure calls, will not be allowed in the Windows Store)

execUnsafeLocalFunction - overrides HTML injection security

Managing WinJS on the enterprise

What are the development costs? Effectiveness vs. C#/XAML or C++ Migration of previous code? What happens to legacy applications on C#? What happens to legacy web applications that we want to migrate to

Windows 8? How to write internal applications and deploy – next slide

Enterprise story (unofficial)

Internal Windows Store for enterprise applications Deployment by employees to their machines from a restricted pool of

applications Enforces security policies Creates a contained environment for controlling what applications are

on enterprise machines

Testing for Submission - WACK

The submission process involves automatic testing Windows App Certification Kit Microsoft provides a testing kit for developers to test their

applications in advance Tests security, performance, etc. Subjectivity kept to a minimum, maximum transparency

Questions?dmitria@bluemetal.com

#dartamonhttp://blog.bluemetal.com