This document provides an introduction and overview of WinJS, including: - What WinJS is and what's under the hood technically - How WinJS fits into app development and what's new - Examples of patterns like MVVM and regions when using WinJS - Considerations for managing WinJS apps in an enterprise setting - The process for testing WinJS apps for submission to the Windows Store The presentation covers the basics of WinJS while not discussing more advanced topics like tiles, sensors, or background tasks.

1. Introduction to WinJS
Dmitri Artamonov
BlueMetal Architects
dmitria@bluemetal.com
#dartamon

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8. 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

9. 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…

10. 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?

11. 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

13. 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?

14. Under the hood (cont’d)
 Chakra engine for Javascript interpretation

15. 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

17. Other JS Libraries
 jQuery
 Graphing (HighCharts or Raphael)
 MVC libraries
 You can create applications without using WinJS at all!

18. What’s new?
 Page Structure/Navigation
 Promises
 Cloud Integration
 Contracts
 Tiles and Notifications
 Speech Integration

19. 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

20. 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
});

21. 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

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

23. 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

27. 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

28. 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 context
HTML5:
<span data-win-bind=“innerText: dto.title”></span>
JS:
WinJS.Binding.processAll(target element, data context object)

29. 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

30. 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

31. 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);

32. 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 namespaces
RepairBills: WinJS.Class.define(function(quantity) { // constructor
code goes here },
{ GetCost: _getCost }, // instance members
{ repairBillTypes: [ “S", “U" ] }) // static members
});

33. 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

34. 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

35. 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

37. 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

38. Questions?
dmitria@bluemetal.com
#dartamon
http://blog.bluemetal.com