Andy Wigley | Technical EvangelistMatthias Shapiro | Program Manager / Technical Evangelist

Building Apps for Windows Phone 8.1Jump Start

Meet Andy Wigley | @andy_wigley • Technical Evangelist in Microsoft Developer

Experience and Evangelism (DX)• Mobile developer for over a decade, worked with WAP, ASP.NET Mobile

Controls, Windows Mobile and Windows Phone• Co-presenter of Windows Phone Jump Start for versions 7.0, 7.1, 8 and now 8.1

• Writer, Teacher and Presenter • Blog at http://andywigley.com • Written a number of books for Microsoft Press, including Mobile Development

Handbook (don’t buy, unless you’re working with .NET Compact Framework on Windows Mobile/CE!)

• Frequent speaker at industry conferences on all topics mobile• Rock-star (well, I play in a small – but popular – band )

Meet Matthias Shapiro | @matthiasshap

• Program Manager, Microsoft• Windows Phone Developer and Evangelist• Long-time XAML developer, from WPF to Silverlight to Windows Phone

• Windows Phone Demo-Writer and Noise-Maker (blog, Twitter)• Bigger bloggy things - http://blogs.msdn.com/b/matthiasshapiro/ • Code snippets – http://codeiuse.tumblr.com

Course Topics

Building Apps for Windows Phone 8.101 | Introducing the Windows Phone 8.1 App Development Platform

06 | Adapting UI for Different Screens and Orientations

02 | Getting Started Building Windows Runtime Apps

07 | Windows Runtime App Lifecycle

03 | Page Navigation and Data Binding in Windows Runtime Apps

08 | Localization and Globalization in

Windows Runtime Apps

04 | Lists and List Items in Windows Runtime Apps

09 | Data Storage, Backup and Roaming

05 | Programming Page Controls and Page Transition Animations

10 | Sharing Files and Data in Windows Phone 8.1

Course Topics

Building Apps for Windows Phone 8.1

11 | Background Tasks and Multitasking

16 | Interacting with User Data: Contacts and Appointments

12 | Maps, Geolocation and Geofencing

17 | Camera, Media and Audio in Windows Phone 8.1

13 | Networking, Mobile Services and

Authentication

18 | Enterprise in Windows Phone 8.1

14 | Tiles, Notifications and Action Center

19 | Programming SQLite on Windows Phone 8.1

15 | Sensors and Proximity: NFC and Bluetooth

20 | Tooling and Diagnostics

Course Topics

Building Apps for Windows Phone 8.121 | App packaging, monetization and publication

22 | Best practices: Building Universal Apps for Windows and Windows Phone

23 | Silverlight apps on Windows Phone 8.1

Andy Wigley @andy_wigleyMatthias Shapiro @matthiasshap

Background Tasks and Multitasking

Windows XAML+

Silverlight 8.1

30 April 2014

Building Apps for Windows Phone 8.1 Jump Start

In this module…

Multitasking on Windows PhoneProgramming background tasksBackground tasks run in response to triggersConditions on background task executionPush notifications trigger example

Mobile multitasking model

Apps not on screen are suspended

However apps can provide real-time content even when suspended

1. Live tiles or toasts2. Scheduled toasts and notifications 3. OS brokered tasks4. Background tasks and agents

Scheduled Task

PeriodicTask, ResourceIntensiveTask

Background Transfer Service

Background Location Tracking

VOIP and Audio Agents

Background Execution in WP8

Windows Phone 8.1 Background Tasks

Background tasks

An app can register background tasksTasks are scheduled and run by the OS, but are background ‘extensions’ of the foreground app

Same permissions from manifest, same storage, same file access, etc.Resource usage is constrained by the systemForeground app (if running) has limited communications with its tasks

Tasks can fire progress/completed events into the foreground appTasks can read/write the same storage as the foreground app

Tasks can use toast, tile, badge UI

An app’s existing task registrations can be queried from the systemAn app can have more than one background task

Creating a background task in your solutionAdd a new project to your solutionUse the Windows Runtime Component template

In your foreground app project, add reference to the Background Task project

Writing a background task

Background Task infrastructure can send a Cancelation notification if task is idle or not responding, but if memory cap is exceeded, task can be terminated without notification. Your task needs to be resilient to rude terminations without a Canceled event firing.

You register background asks to run in response to triggers firing

Tasks run in response to triggersTrigger Notes

System Trigger Runs on a specified system event.Events: UserPresent/Away, NetworkStateChange, InternetAvailable, SessionConnected, ServicingComplete, TimeZoneChange Note: LockScreenApplicationAdded and LockScreenApplicationRemoved are not supported on Windows Phone

TimeTrigger Runs on a frequency (minimum gap of 30 minutes)

LocationTrigger Runs as user enters/leaves a geofenced location

MaintenanceTrigger Runs on a frequency (minimum gap of 30 minutes)but only when the device is on AC power

PushNotificationTrigger Runs in response to an incoming raw push notification sent to the app.

Tasks run in response to triggersTrigger Notes

RfcommConnectionTrigger Bluetooth: when an RFCOMM connection has been established.

DeviceChangeTrigger Bluetooth: when an ACL connection has been created/destroyed.

BluetoothSignalStrengthTrigger Bluetooth: when signal strength goes outside of bounds.

GattCharacteristicNotificationTrigger

Bluetooth: when a characteristic change is received from a Bluetooth LE device

Note: ControlChannelTrigger, used on Windows to hold open a TCP/IP channel and trigger on incoming data, is not supported on Windows Phone

Conditions

ConditionUser[Not]PresentInternet[Not]AvailableFreeNetworkAvailableBackgroundWorkCostNotHigh

“run this task every 30 minutes if the internet is available”

Registration needs manifest entry

should not have to specify an executable for the background task host here.

Requesting background task access

Requesting background task access

async void RegisterBackgroundTasks() { // On Windows, RequestAccessAsync presents the user with a confirmation // dialog that requests that an app be allowed on the lock screen. // On Windows Phone, RequestAccessAsync does not show any user confirmation UI // but *must* be called before registering any tasks var access = await BackgroundExecutionManager.RequestAccessAsync();

// A 'good' status return on Phone is BackgroundAccess.AllowedMayUseActiveRealTimeConnectivity if (access == BackgroundAccessStatus.Denied) { // Either the user has explicitly denied background execution for this app // or the maximum number of background apps across the system has been reached // Display some informative message to the user... } }

New in Windows Phone 8.1

Sort and manage which apps can execute in the background

Controls number of apps that can run in the background

Battery Saver

Registering a background task

BackgroundTaskBuilder taskBuilder = new BackgroundTaskBuilder(); taskBuilder.Name = "MyBackgroundTask";

// Many different trigger types could be used here SystemTrigger trigger = new SystemTrigger(SystemTriggerType.TimeZoneChange, false); taskBuilder.SetTrigger(trigger); taskBuilder.AddCondition(new SystemCondition(SystemConditionType.InternetAvailable));

// Entry point is the full name of our IBackgroundTask implementation // Good practice to use reflection as here to ensure correct name taskBuilder.TaskEntryPoint = typeof(MyBackgroundTask.TheTask).FullName;

BackgroundTaskRegistration registration = taskBuilder.Register();

// Optionally, handle the progress/completed events of the task registration.Progress += registration_Progress; registration.Completed += registration_Completed;

Querying task registrations

// AllTasks is a dictionary <Guid, IBackgroundTaskRegistration> so you can get back // to your registration by id or by posiiton, or select First if you only have one registration. var taskRegistration = BackgroundTaskRegistration.AllTasks.Values.FirstOrDefault();

// We could then unregister the task, optionally cancelling any running instance if (taskRegistration != null) { taskRegistration.Unregister(true); }

// Release the progress/completed event subscriptions registration.Progress -= registration_Progress; registration.Completed -= registration_Completed;

Debugger can launch tasks

You can manually invoke your background task code using the debugger (once the registration code has been run)

Background tasks demo

Example: push notification trigger

Push notification triggers

Football ScoreCloud

Service

Windows Notification

Service

PushBackground

TaskStorage

0:32m Man City 1 Man Utd 0

0:47m Man City 1 Man Utd 1

0:85m Man City 2 Man Utd 1

End: Man City 2 Man Utd 1

<?xml version=“1.0”> Type = raw, Data = Man City....</xml>

123

Football News: Your Team Won!

4

<?xml version=“1.0”> Type = raw, Data = End Game</xml>

<?xml version=“1.0”> Type = raw, Data = Man City....</xml>

<?xml version=“1.0”> Type = raw, Data = Man City....</xml>

ForegroundApp

Push Notifications trigger

demo

Resource constraints

Resource constraints

All background tasks have CPU, memory and network quotasQuotas are based on actual CPU usage instead of wall clock time limits only. On Windows Phone, CPU usage quota is 2 seconds per app, refreshed every 15 minutes.Wall-clock CPU quota will also be enforced (at least 30 secs)Memory quota scales based on device capabilitiesTimeTrigger will have a 30 min floor on Phone

Call RequestAccessAsync() to get your full quota!

On 512MB devices, number of background apps is limitedIf exceeded, call to RequestAccessAsync will return Denied

Memory Caps in MB

Background task type 512 MB 1 GB 2 GB or greater

Location 16 30 40

Bluetooth 16 16 16

Servicing Complete 10 10 10

Other background tasks 16 30 40

Limit while debugging 30 40 50

Not supported in Windows Phone Store Apps

Apps that run under the lock-screen

Continuous background location tracking apps

VoIP agent (incoming call, progress etc.)

Foreground agents (WalletAgent)

Related topicsBackground audio See Session 17: Camera, Media and Audio

Background file transfer service See Session 13: Networking and Mobile Services

Notification mechanisms See Session 10: Tiles, badges and toasts and Notification Center

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