Working with disconnected data in Windows Store apps Alex Casquete

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Agenda

Disconnected scenarios SQLite IndexedDB Windows Azure Mobile Services CouchDB Synchronize

SQLite with Mobile Services IndexedDB with CouchDB

About me

Alex CasqueteMCT since 2010 Mobile Solutions Developeralex@casquete.es acasquete

Disconnected Scenarios

Disconnected Scenarios

In a connected World sometimes you are disconnected. Network bandwidth is more restricted. Less storage and processing capacity. You are not alone. Conflict resolution is necessary.

The applications require a local storage

Local Storage

SQLiteApp Data StoreFile System IndexedDB

C# / JavaScript Javascript

Open source RDBMS. Works as library instead of service Single file database. Cross Platform database. Implements most of the SQL standard.

What is SQLite?

DEMO: SQLite

Windows Azure Mobile Services

Data

Notifications

Auth

Server Logic Logging & Diag

ScaleScheduler

Key ScenariosWindows Azure Mobile Services are ideal for:

Modern mobile appsWindows Store Apps, Windows Phone, iOS, Android

Common ScenariosReduces the friction associated with repeating common tasks such as user authentication, push notifications and structured storage

Rapid DevelopmentTime is money. Get your app up and running sooner when you use Mobile Services to configure a straightforward and secure backend in less than five minutes.

DEMO: WAMS & Synchronization

Write changes to the same item, at the same time. Without any conflict detection, the last write would

overwrite any previous updates. Optimistic Concurrency Control assumes that each

transaction can commit. And verifies that no other transaction has modified the

data. WAMS detects write conflicts with __version property.

Conflict detection

DEMO: Conflict Resolution

And JavaScript?

Local Storage

SQLiteApp Data StoreFile System IndexedDB

C# / JavaScript Javascript

Supported by many browsers and also by Windows Store apps.

Each record is identified by a unique index or key. Store large amounts of structured data. API doesn’t give a way to synchronize the data.

What is IndexedDB?

Using IndexedDB

// Opening a Databasevar dbRequest = window.indexedDB.open("ContactsDB", version);

// Assume db is a database variable opened earliervar transaction = db.transaction(["people"],"readwrite");var store = transaction.objectStore("people");

// Define a personvar person = { name:name, email:email, created:new Date() }

// Perform the addvar request = store.add(person,1);

PouchDB is a implementation of Apache CouchDB Works in Firefox, Chrome, Opera, Safari, IE and Node.js and

Windows Store apps Same Data model Same API Same conflicts resolution Synchronizes with a CouchDB Database!

PouchDB

DEMO: PouchDB

Using PouchDB

// Opening a Databasevar db = new PouchDB('dbname');// Add an objectdb.put({ _id: ’me@email.com', name: ’Alex', age: 66 });// Subscripbe to changesdb.changes({ onChange: function() { console.log('Ch-Ch-Changes'); }});// Replicate to external DBdb.replicate.to('http://example.com/mydb');

Remember

Complete the user experience in your apps using offline capabilities

Use DB engines instead of implementing a new mechanism to store data

Synchronization is not simple!

Resources

Handling Database Write Conflicts with WAMS http://www.windowsazure.com/en-us/develop/mobile/tutorials/handle-database-wri

te-conflicts-dotnet/ SQL Data Sync (Preview)

http://msdn.microsoft.com/en-us/library/windowsazure/hh456371.aspx SQLite Documentation

http://www.sqlite.org/docs.html PouchDB

http://pouchdb.com

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