Building a chat app with windows azure mobile

Building a cross-platform chat app
with Microsoft Azure Mobile
Services
14 may 2014, Timisoara
Timisoara .Net Meetup #1

Flavius Radu Demian
Software developer, Avaelgo
I really like programming, especially web and mobile
Please feel free to ask questions any time and don’t be shy
Knowledge is power 
flaviusdemian91@yahoo.com | flavius.demian@gmail.com | @slowarad

Expectations
Learn how to use mobile services
Learn when to use mobile services
Learn the strengths and limitations of mobile services
Learn that mobile services wants to be friend with everyone
Make you curious  => go home and play with it

Agenda
Overview
Storage
Custom API
Authentication & Authorization
Scheduler

Agenda
Diagnostics & Logging
Scale
Cool Third Party Add-Ons
Design of the chat app
Review

Overview
Mobile Services allows you to accelerate your mobile app
development by providing a turnkey way to structure storage,
authenticate users, and send push notifications.
With SDKs for Windows, Android, iOS, and HTML as well as a
powerful and flexible REST API, Mobile Services lets you to
build connected applications for any platform and deliver a
consistent experience across devices.

Overview
Clients for:
Windows Store, Windows Phone 8, iOS, Android, Javascript
You can add a cloud backend to your app in minutes without
the need for server code
The backend login can be written in node.js or c# (preview)
The SDK’s are open source (on github) , it’s integrated with GIT

Overview
Easily build a backend for mobile apps and not only
Easily manipulate data (filters)
Easily authenticate users
Send push notifications
Integrate your favorite services and great community

Server side logic
Node.js
Is a software platform for scalable server-side and networking
applications
Applications are written in JavaScript can be run within the
Node.js runtime on Windows, Mac OS X and Linux with no
changes
It is written in

Storage
Windows Azure SQL Database
Dynamic schema on/off
REST API generated per table -> Data centric platform
Access your data through :
Portal, SQL Management Studio, Rest API

Storage
JSON to SQL data types conversions

“Data Centric” Server Logic
Backend runs Node JS on small azure VM’s
“Interceptors” exposed for all CRUD requests to all tables
You get access to a predefined set of node modules :
request, console, push.*, tables, statusCodes, azure, mssql

Custom API
You can write your own API very easily and quickly
If you need you can add extra Node JS packages
exports.get = function(req, res) { /* code here */ }
exports.post = function(req, res) {/* code here */ }

Small demo time part 1
Login in the portal and create a mobile service
Set GIT credentials and get repository
Create some tables, show interceptors
Create a custom API
See list of predefined packages -> click here

Push notifications
The notification provider server maintains a "persistent IP
connection" with your device in order to deliver notifications
when the app needs to 'say' something to you.
Payload limited, specific to platform
The global push object is used to send push notifications
Success and Error callbacks are provided

Push notifications
Platform specific providers:

Push notifications overview
1) The app requests a channel from the
Notifications Provider
2) The app sends the channel url to
Mobile Services which stores it
3) When a notification is sent, Mobile
Services executes something like this:
push.mpns.send(channelUri….)
Windows Phone case study
4) The notification goes through the Notifications Provider which forwards it to the device

Authentication & Authorization
You can make provide quick auth in your app with
Facebook Twitter Google Microsoft
and Windows Azure Active Directory

Authorization
Table level authorization for CRUD operation
Everyone -> any request by anyone is accepted
Anyone with Application Key -> app key is sent on the request
distributed (default)
Authenticated Users -> users authenticated with one of the
mentioned identity providers

Authorization
Table level authorization for CRUD operation (*cont)
Scripts and Admins -> registers scripts or requests via the
master key
The application key is not secure and should not be used to
authenticate users of your app, especially in production

Scheduler
It runs jobs on simple or complex recurring schedules such as:
1) Send broadcast push notifications
2) Processing or resizing stored images
3) Invoking a Web Service over HTTP/s
4) Post a message to a Windows Azure Storage Queue, etc

Diagnostics and Logging
View diagnostics directly in the portal including :
1) API calls
2) CPU time
3) Data Out
LoggingConsole.* operations like console.log and console.error
provide an easy means to debug your server side scripts.

Scale
Compute - scale between shared and reserved mode
Increase/decrease your instance count
Storage ability to scale out your mobile service tenant(s) to a
dedicated SQL DB
Ability to scale up your SQL DB from web through business to
150GB. Since Microsoft Build it is up to 500GB .

Small demo time part 2
Push notifications
Authentication
Authorization
Diagnostics
Logging
Scale

Code cheat sheet - client
public MobileServiceClient MobileService = new MobileServiceClient(“dns”,“key");
public IMobileServiceTable<UserEntity> Users = App.MobileService.GetTable<UserEntity>();
public MobileServiceUser MobileServicesUser = await App.MobileService.LoginAsync(provider);
await UsersTable.InsertAsync(App.CurrentUser);
result = await App.MobileService.InvokeApiAsync<T>(“link”, HttpMethod.Get, extraParams);
App.MobileService.Logout();

Code cheat sheet – server (interceptor)
function insert(item, user, request) {
console.log("item is: " + JSON.stringify(item));
var sql = "SELECT name FROM UserEntity WHERE providerIdLong = ? AND identityProvider = ?";
mssql.query(sql, [item.providerIdLong, item.identityProvider], {
success: function(results) {
if( results.length == 0){
results = null;
}
completeUserProfile(item, user, request, results);
},
error: function(err) {
request.respond(statusCodes.BAD_REQUEST, { message: err });
}
});
}

Code cheat sheet – server (Api)
exports.get = function(req, res) {
var userTable = req.service.tables.getTable('userEntity');
var userToExclude = req.query.userId;
userTable.read({
success: function (items) {
if (items.length > 0) {
var finalResults = [], currentEntry = null;
items.forEach(function(item) {
if( item.providerIdLong != userToExclude){
currentEntry = new Object(); currentEntry.name = item.name;
finalResults.push(currentEntry);
}
});
res.send(statusCodes.OK, finalResults);
} }
}); };

Code cheat sheet – server (push)
if (entry.deviceType === "Android") //Android
{
var payload = new Object();
payload.content = item.content;
payload.fromId = item.fromId;
payload.fromPicture = item.fromPicture;
payload.fromName = item.fromName;
push.gcm.send(entry.registrationId, JSON.stringify(payload), {
success: function(response) {
console.log('Android Push notification sent: ', response);
}, error: function(error) {
console.log('Android Error sending push notification android: ', error);
}
});
}

Cool Third Party Add-Ons
Real time communication Emails SMS

Let’s talk about the chat app

Design - Functionalities
Integrate Microsoft Azure Mobile Services
Integrate with social media providers
Store data to cloud after auth ( user and channel related data )
Retrieve the rest of the users you can talk to (custom API)
Send message functionality
Receive message functionality
Logout functionality

Design - Database
Tables: users, channels, messages
Channel
ChannelUri
RegistrationId
UserProviderId
DeviceType
Message
FromId
ToId
DeviceType
FromName
FromPicture
User
ProviderId
Name
Picture
AccessToken
AccessTokenSecret

Let’s show some code
But first let’s see a short teaser

Review of Azure Mobile Services
Create a scalable and secure backend for your Windows, Android
and iOS apps
Store data in the cloud
Easily authenticate users
Send push notifications

Review of Azure Mobile Services
Consume your favorite services
Monitor, alert, and auto scale
Cheap and FREE in some cases -> click here
Preview: No availability Service Level Agreement
Paid: General Availability: 99.9%

Building a chat app with windows azure mobile

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