This document discusses sending cross-platform notifications using Azure Notifications Hub and Xamarin. It covers push notification lifecycles, challenges, advantages of Notification Hubs including cross-platform support and interest groups. It also discusses using tags to send targeted notifications, templates for localization and multi-platform support, and managing devices and tags from the backend. Advanced scenarios discussed include "push to sync" to update app state and retargeting notifications based on user data analysis.

1. Sending Cross Platform Notifications
using Azure Notifications Hub &
Xamarin
Anubhav Ranjan
Consultant at Xamarin,
Microsoft MVP
@anubhavr05
Sukriti Sharma
Technical Evangelist
@suksharma

2. Agenda
• Push Notifications
• Notification Hub
• Tags: Send Targeted Notifications
• Templates

3. Push Notifications are BIG

4. Push notification lifecycle
Registration at app launch
1. Client app to retrieve PNS Handle (e.g. Channel Uris,
device tokens, registration IDs)
2. Updates back-end
Sending Notification
1. Back-end sends notification to PNS
2. PNS pushes the notification to the app on the device
Maintenance
1. Delete expired handles when PNS rejects them
Platform
Notification
Service
App back-end

5. Challenges of push notifications
• Different protocols to PNS’ (e.g. HTTP vs TCP, xml payload vs json
payload)
• Tiles vs toasts vs badges
• Maintaining ChannelURI/ RegistrationID/ Token provided by PNS
• Back-end complications (Storage) and Cost
• Scalability

6. Azure Notification Hubs (advantages)
• X-plat: from any back-end to any mobile platform
• No need to store device information in the app back-end (managed)
• Routing and interest groups
• Personalization and localization
• Broadcast at scale, multicast, unicast
• Telemetry

7. Using Notification Hubs
One-time set up
1. Create NH
Register (Client)
1. Retrieve PNS Handle
2. Register with NH using PNS Handle
Send Notification
1. Back-end sends message to NH
2. NH pushes it to the PNS’
*PNS – Platform Notification Service
*NH – Notifications Hub
APNsWNS
Notification Hub
App back-end
iOS app Windows app
MPNS
GCM
ADM

8. •Client SDKs for
• Android – GCM and ADM
• iOS – APNS
• Windows Phone – MPNS
• Windows Store – WNS
•Capable of pushing to specific platform or to all at once
•Server SDKs for
• REST API
• .NET
• Node.JS
• Java
Cross-Platform Push

9. Some snippets
Register Send
await
[hub
registerNativeWithDeviceToken:deviceToken
tags:nil
completion:^(NSError* error) {…}];
hub.register(regid);
var toast = @“<notification payload>";
hub.SendWindowsNativeNotificationAsync(toas
t);
hubService.wns.sendToastText01(null,
{
text1: 'Hello from Node!'
},
function (error)
{
…
}
);

10. Send Targeted Notifications

11. Tags
Tags as interest groups
1. Client app registers with tags
2. Tags are simple strings (no pre-provisioning is required)
3. Back-end can target all clients with the same tag
You can use tags also for
• Multiple type of interest groups, e.g.
• Follow movie stars: tag “followactor:Rajnikant”
• Follow users: tag “followuser:SachinTendulkar”
• Tags can be user preferences or system information

12. Notification Hub
App back-end
Tag:”Rajnikant”Tag:”Salman”
Tag:”Rajnikant”
Tags: Example

13. • Logic based tag pushed
• Social: “All of this group but me”
• Group:id && !user:id
• Events: “Anyone interested in the game”
• FollowTeam:RealMadrid || FollowTeam:Barcelona || EventInterest:LaLiga
• Time: “@12PM in India send”
• timezone:IST && follows:chinesefood
Tag Expressions

14. Some snippets
Register
await new string[] {"myTag", "myOtherTag"}
[hub registerNativeWithDeviceToken:deviceToken tags:@[@"myTag", @"myOtherTag"] completion:
^(NSError* error) {
…
}];
hub.register(regid, "myTag“, "myOtherTag");

15. Demo: Get Started
- Portal Demo
- Google Console
- Configure your Notification Hub
- Connecting your app to the Notification Hub
- Send notifications from your back-end
- Register with Tags

16. Notification Templates

17. Using templates for multi-platform push
Registration
• Client apps can register with a platform specific template,
e.g.
• Windows tablet registers with Windows Store ToastText01 template
• iPhone with the Apple JSON template:
{ aps: {alert: “$(message)”}}
Send notification
• App back-end sends a platform independent message:
{message: “Hello!”}
Notes
• Multiple templates can be specified for each device
• Each template can have a different set of tags
Notification Hub
App back-end
<toast>
<visual>
<binding template="ToastText01">
<text id="1">$(message)</text>
</binding>
</visual>
</toast>
{
aps: {
alert:
“$(message)”
}
}
{
message: “Hello!”
}
Hello!
Hello!

18. Using templates for localization
Registration
• Client apps can register with personalized templates, e.g.
• Windows tablet wants to receive news in English
• iPhone wants Italian
Send notification
• App back-end sends a message including both languages:
{news_en: “Hello!”, news_it: “Ciao!”}
Notification Hub
App back-end
<toast>
<visual>
<binding
template="ToastText01">
<text id="1">$(news_en)</text>
</binding>
</visual>
</toast>
{
aps: {
alert:
“$(news_it)”
}
}
{
news_en: “Hello!”,
news_it: “Ciao!”
}
Hello!
Ciao!

19. Sending geo-targeted notifications with
Windows Azure Notification Hubs
Some examples are:
• Send coupons to all my customers in Mumbai
• Send notifications of new mortgage rates/open houses in a
specific locality
• Notify people in a town/city about a concert they might be
interested in
• Notify people in a town/city of a charity/recycling event

20. “How do I read tags from my hub?”
• Notification Hubs is not a storage system
• No cleanup needed, expires registrations automatically
• In the device
• Every platform provides apps a way to store user information locally or in the
cloud
• E.g. Roaming settings, iCloud
• In your app back-end
• Usually stored by user id
• Try not to replicate device information
• Register methods always overwrite tags
• Each time you update the channel, overwrite all the tags

21. Managing devices from your back-end
When to register from your app back-end
• To secure Tags
• App back-end can authenticate the user before registering the device
• When back-end has to modify tags
• Adding a tag from the web app
• Manager adding an employee to a work group
• Tags are derived from analytics or other user data

22. Registering from the back-end
Identify your device
1. Cannot use ChannelURIs/device tokens/…
2. Keep long-living NH registration ids in device storage
Register
1. First time only,
a) Request registration id from hub, and
b) Store it on device storage
2. CreateOrUpdate device registration (@ every app start)
3. Back-end can verify and/or add tags (e.g. performing auth)
Notification Hub
App back-end
{id}
upsert({id}, channel, tags)
createId()
Managing devices from your back-end

23. Back-end driven tag updates
Use a tag to identify user
1. Back-end usually refers to users and not devices
2. Register devices with a tag like ‘userid:{id}’
Back-end updates tags
1. Retrieve device registration(s) by userid
2. Update tags
Note
1. No device information in app back-end
2. Back-end only refers to users
Notification Hub
App back-end
getByTag(userid)
update(tags)
Managing devices from your back-end

24. Advanced scenarios: “Push to Sync”, Retargeting

25. Push to Sync
Updates app state
1. Does not show a message to the user
Example: music app
1. User changes playlist on desktop
2. Back-end sends a ‘push-to-sync’ notifications to user’s devices
3. Phone receives push and starts downloading new song
4. User finds the new song already on their phone!
Platform-dependent
Windows/Windows Phone (only lock-screen apps)
iOS (only since iOS 7)
Android/Kindle
App back-end
Notification Hub
Push to sync
Add new song

26. Pulling it all together - Retargeting
Send a targeted coupon
1. Use tags for user preferences, location, system properties,
timezone, …
2. Target with tag expressions
Push UX & feedback
1. Use Rich push & push to sync to provide best UX
2. Contextually report to your app back-end
(who tapped, who visited the page, who received it)
Retarget
1. (perform analysis on user data)
2. Update tags from your back-end with the new information
3. Send alternative offer to users that did not participate
App back-end
Notification Hub
Loc:SF && Food
Update tags
Loc:SF && Food
&& !tapped
CRM/DMP
system

27. Follow us online
Facebook
facebook.com/MicrosoftDeveloper.India
twitter.com/msdevindia
Twitter
@anubhavr05
@suksharma