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Session III – Lifecycle and More
Daryl Rudolph
Agenda
ApplicationLifecycle
Live Tiles, Background Process andLock Screen
Implementing the Search Contract
Application Lifecycle
Show the flow
Feel Connected and Alive
Memory Management
User selects app for foreground
System manages app lifetime
User launches many apps
User manages app lifetime
App process lifetime
RunningApp
SuspendedApp
Suspending Terminated
AppLow
MemoryResumin
g
Application States
Running
SuspendedNot Running
Resuming
Activated Suspending
Process lifetime walkthrough
App 1 App 2 App 3Running
Suspended
Terminated
… App N
Apps suspend after a short
delay
App terminated under memory
pressure without notification
Apps resume instantly from
suspend
When do apps get terminated
• System needs more memory• User switch occurs• System shutdown• Apps crash
Apps do not get notified when they are getting
terminated
Process state transitions
Running
App
SuspendedApp
suspendingTermina
tedApp
Low Memory
Code gets to runNo
code runs
App not running
resuming
App gets 5seconds to
handle suspend
App is not notified before
termination
Apps are notified when they have been resumed
User Launches App
Splash screen
Suspend under the hood
• Suspended apps are not scheduled by the NT Kernel
• No CPU, Disk or Network consumed• All threads are suspended• Apps remain in memory• Kernel ensures apps are not suspended in critical
sections that could cause system wide deadlocks• Apps instantly resumed from suspend when
brought to foreground
Interacting with your users
Entice Discover Share
App Activation Through Contracts
• Apps are activated through contracts• Launch, search, ShareTarget, etc.
• Apps need to initialize contract specific actions
• Context is provided
Running App
launch
shareTarget
activated
kind
search
App crash? Start over
• Apps that are stuck are no fun• Your app can be terminated abruptly in any of
these cases• Too long to load• Too long to suspend• Stopped handling input messages (Blocking I/O on UI
thread)• Task manager
• Bring the user back home, and ignore saved user session state
• previousExecutionState is provided in activation event args
Best practices for saving and restoring state
Scenario You should….User is using your App
• Save user data incrementally
App switched away from (Suspending)
• Save where the user is – what screen they are on, for example
Not running App launched by user (Activated)
• Bring the user back and restore their session as if they never left
Suspended App launched by user (Resuming)
• Do nothing
Demo
Suspend Demo
Search Contract
Finding your application
Use the Right Contracts
Search 1 2 3
1. Search box is scoped to the main app on screen
2. Query suggestions provided by the main app on screen• Autocompletes to terms for
which the app has search results
3. List of installed Windows 8 style apps that have implemented the search contract
2
3
1
Query submitted
User
Show Search results view
Yes
Show previous
search results view
NoQuery chang
ed?
User enters a query and hits
Search
User selects a query
suggestion
Search Pane
Submit query to App
Search App
Query Submitted
Event
Demo
Search Contract Demo
Live tiles
Keep the action going
Invest in a Great Tile
Tiles Sizes• Tap on tile to launch or switch to an
app
• Static default tile specified in app manifest
• Two sizes:
Both sizes can have live updates
Wide (2x1)
310X150
Square (1x1)
150X150
Badges
• Overlays status on top of tile• Supports square and wide tiles• Number up to 99 or pre-defined glyph:
• Always legible on top of images
BadgeBadge
Notification Queuing
• By default only last notification shown• Opt-in to automatically cycle tile through last five
notifications
Live Tiles things to remember
• Tiles updated using pre-defined templates
• Text-only, image-only or combination• JPEG or PNG only, max size 150 KB• Local, cloud or background updates
Invest in a Great Tile
Demo
Live Tiles
Secondary Tiles
• Tiles created by “pinning” content from app
• Pin initiated by app via simple runtime call
• User confirms pin operation via system UI
• Exposes a personalized surface for app
• Same capabilities as app tiles• Launch leads to relevant content
Demo
Secondary Tiles
RTC – Real Time Communication apps
Keep the action going
Invest in a Great Tile
Review app process lifetime
RunningApp
SuspendedApp
Suspending Terminated
AppLow
MemoryResumin
g
…with RTC apps
RunningApp
SuspendedApp
Suspending Terminated
AppLow
MemoryResumin
g
BackgroundTask
Executes
The app lifecycle
BackgroundTask
Executes
BackgroundTask
Executes
Network Trigger
RTC trigger APIs
System Trigger Time Trigger
Background Task Infrastructure
VoIP IM Your App
App
OS
Network Trigger
System Trigger
Time Trigger
Background Task Infrastructure
VoIP IM Mail
Changing Live Tile
Time Trigger
Setting up a Time Trigger
Live tiles with push notifications
• Tiles can be updated even if your app is not running!
• Push notifications can be used to remotely update a tile on the Start screen
• Great for showing the newest content available to your users
App Cloud Service
Windows Push Notification Service
(WNS)
HTTP POST
Notification Delivered
Push Notification Overview
1. Request Channel URI
2. Register with your Cloud Service
3. Authenticate & Push Notification
Windows 8
Notification
Client Platform
Windows 8 Style
App
App Service
Windows Push Notification
Service
1
2
3
3
POST <channel URI> HTTP/1.1Content-Type: text/xmlHost: db3.notify.windows.comX-WNS-Type: wns/badgeAuthorization: Bearer <authentication token>Content-Length: 58
<?xml version="1.0" encoding="utf-8"?><badge value="11"/>
Register for Time TriggerTime Trigger
using Windows.ApplicationModel.Background;
// Specify the triggerTimeTrigger trigger = new TimeTrigger(UpdateInterval, Periodic);
Create time
trigger
// Associate app code with the triggerBackgroundTaskBuilder taskBuilder = new BackgroundTaskBuilder();taskBuilder.TaskEntryPoint = “MyApp.Background.UpdateEmailTask";taskBuilder.SetTrigger(trigger);taskBuilder.Name = “TimerExpiry";
Associate trigger
with app code
// Register the task for background executionIBackgroundTaskRegistration taskRegistration = taskBuilder.Register();
Register trigger
public sealed class UpdateLiveTileTask : IBackgroundTask { public void Run(IBackgroundTaskInstance taskInstance) {
// Your app code to update email }}}
using Windows.ApplicationModel.Background;
Time Trigger App execution upon
timer expiry
Demo
Live Tiles /Lock Screen/Background
Best Practices for Tiles
• Display new, tailored and engaging content to the user
• Keep tile fresh by updating as your app content changes
• Reference content that lives on your app’s home page so the user can find it easily.
• Keep content safely ignorable and glanceable - for short messages only
• Use square size if tile is not live• No display ads!
Agenda
ApplicationLifecycle
Live Tiles, Background Process andLock Screen
Implementing the Search Contract
Hands-On Lab 3 OR Create your own app
Running in the background
Create your own app
• You can work on Hands-on Lab 3 OR Create your own app• You have until 4:20 PM• Don’t have to decide if you are entering until 4:20 PM• Presentation can be PowerPoint and/or demonstration
• Must let me know beforehand if you don’t have VGA connection
• Each contestant will have exactly 3 minutes to present!• Be creative. Keep in mind the traits of a great Windows 8
app!
• Note: Anyone who attended today can enter to win the app contest sponsored by Component Art for a $10,000 grand prize, even if you don’t enter today’s contest.
Contact/References
• Magenic – http://www.magenic.com• Daryl Rudolph – [email protected]
• http://dev.windows.com
• http://design.windows.com
• API Sites• http://www.restfulwebservices.net• http://developer.mashery.com/apis• http://www.programmableweb.com