MOBILE APPLICATIONS AND CLOUD COMPUTING. Roberto Beraldi

MOBILE APPLICATIONS

AND CLOUD

COMPUTING

Course Outline

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6 CFUs

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Topics:

• Mobile application programming (Android) • Cloud computing

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To pass the exam:

• Individual working and documented application in android (possibly

using cloud services)

Key terms

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Cloud computing

• Delivery of remote virtual resources through internet (virtual machines,

storage space, software functions (web api) , data – e.g. open data, etc..)

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Mobile Applications

• app that runs on mobile devices smartphone

• App running on wearable devices, e.g., smartwatch

• Context-Awareness

• sensors

• Where (lat,lon) the device running the application is located

• Other Sensors, e.g., acceleration, orientation, etc

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Connection and synergy between Cloud and Mobile

Cloud computing and mobile applications

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Cloud computing is an umbrella term to refer to a way to

access functionalities remotely (e.g., via Internet)

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There are different ‘delivery models’ of cloud computing

• Software as a Service (SaaS) or Web API • Platform as a Service (PaaS)

• Infrastructure as a Service (Iaas) (virtualization)

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Cloud computing can be used ‘alone’, or…

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Cloud computing, or more simply ‘cloud’, can be exploited

by mobile apps. This can be done in different ways

• One simple possible way is to synchronize data views of different

• Dropbox is a free (up to 2GB), web-based cloud storage mechanism

• file backup service • data sharing

• Data sync among different clients

• Mobile applications iPhone iPad Windows Linux MAC .mp3 .avi .jpg

Freemium business model REST / JSON calls

Dropbox

Example: iCloud from Apple

-contacts -photo -messages .. Phone backup -iCloud drive

(store any kind of document)

Amazon’s Cognito

Amazon’s Cognito

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Amazon Cognito gives you unique identifiers for your end

users and then lets you securely store and sync user app

data in the AWS Cloud across multiple devices and OS

platforms.

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You can do this with just a few lines of code, and your app

can work the same, regardless of whether a user’s

devices are online or offline.

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When new data is available in the sync store, a user’s

devices can be alerted by a silent push notification so that

your app can sync the new data automatically.

Characteristic of a cloud storage service

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Bundling

• When a batch of files is transferred, files could be bundled, so that

transmission latency and control overhead are reduced.

• For example, Dropbox use only few TCP connections to transfer multiple files

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Chunking

• Large files can be either monolithically transmitted to the cloud or

chunked into smaller pieces. Chunking is advantageous because it simplifies recovery in case of failures

• Dropbox 4MB, Google Drive 8MB,…

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Compression

• data compressed before a transfer. Compression could, in general,

reduce traffic and storage requirements at the expense of local processing time.

Characteristic of a cloud storage service

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Deduplication

• Server data deduplication eliminates replicas on the storage server. • Client-side deduplication instead extends the benefits to clients and

the network: In case a file is already present on servers, replicas in the client can be identified to save upload capacity

• This can be accomplished by calculating a file digest using the file

content, e.g., SHA256 is used by Dropbox

• The digest is sent to servers prior to submitting the complete file. • Servers then check whether the digest is already stored in the

system and skip the upload of repeated content.

• Dropbox implements inter-user deduplication: this technique allows a user to skip submitting files that are already stored by any other user.

Characteristic of a cloud storage service

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Delta encoding

• Delta encoding calculates the difference among file revisions,

allowing the transmission of only the modified portions.

• Indeed, delta encoding provides similar benefits as the combination

of chunking and deduplication, but with a finer granularity

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P2P synchronization

• Devices hosting common files could be synchronized without

retrieving every content from the cloud, thus saving both network and server resources

• Dropbox is known for implementing a LAN Sync Protocol that allows devices, possibly from different users, to exchange content using P2P communication when clients are connected to the same LAN.

Comparison among personal cloud

storage(*)

(*)E. Bocchi, I. Drago, M. Mellia, “Personal Cloud Storage Benchmarks and Comparison”, IEEE Transactions on Cloud Computing 2015

Other example: Microsoft’s Intune

Microsoft Intune helps organizations provide their

employees with access to corporate applications, data, and resources from virtually anywhere on almost any device, while helping to keep corporate information secure.

Intune can manage:

Mobile devices (including phones and tablets running Android,

iOS, Windows Phone and Windows RT operating systems).

Computers running a professional edition of Windows Vista,

Cloud and mobile apps

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Other ways to exploit cloud is by implementing a

Google Cloud Messaging (GCM)

push GCM allows to attach up to 1,000

recipients to a single message

-Broadcast receiver

connection server

app server

Amazon’s Simple Notification Service

(SNS)

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It is a fast, flexible, fully managed push notification service

that lets you send individual messages or to fan-out

messages to large numbers of recipients.

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Amazon SNS makes it simple and cost effective to send

push notifications to mobile device users, email recipients

or even send messages to other distributed services.

Amazon’s SNS (features)

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Seamlessly scale from a handful of messages per day to

millions of messages or higher.

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With SNS you can publish a message once, and deliver it one

or more times. So you can choose to direct unique messages

to individual Apple, Google or Amazon devices, or broadcast

deliveries to many mobile devices with a single publish request.

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SNS allows you to group multiple recipients using topics.

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A topic is an “access point” for allowing recipients to

dynamically subscribe for identical copies of the same

notification.

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When you publish once to a topic, SNS delivers appropriately

Mobile apps and Software as a Service

Cloud

-Cloud can play the role of ‘backend’

-provide access to resourses: • Functionality (VM, storage)

using RPC-like calls) • Data (open data)

req reply

Example

req reply

Cloud

real time data on transportation available from ATAC via XML-RPC

http://www.agenziamobilita.roma.it/progetti/open-data/

Mobile apps and web API (aka SaaS)

WEB-API INTERNET

Client Application

A Web API allows to design and develop an application that exploits software

modules accessed via Internet via a simple wire protocol

Web API: programmatic point of view

Programmatic Service Access (many methods) Web URL (standard HTTP methods) web brower HTTP Application HTTP Rest,XML-RPC,etc (Web API)

Mashup applications

P ro vi d e A P ro vi d e r B _… API WEB CLIENT s=A.methodName(par₁) … z=B.methodName(s,par₂)

Mashup applications (1/2)

Client Server Web API

…

Server Web API

…

JSON-RPC Server Web API AJAX Python ..

Mashup applications (2/2)

HTTP -Server Web -”mashupper” (e.g.,dynamic pages Php) WEB API XML-RPC SOAP

Web API and Interoperability

WEB-API Client Application (Technology A) Client Application (Technology B) Client Application (Technology C) ….

Example: Tic Tac Toe

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Monolithic application

• All the logic is in a single program

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Client Server

• The server dynamically generates the page to

be displayed with the response

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Web API (cloud computing style)

• Provides primitive operations to an application

(that can run on a mobile device, for example) and let two players to play

solution1: monolithic app

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Monolithic

Solution 2: client/server

http://game.org/ttt.php?move=7

• Client HTTP Server + php

HTML

Possible technological mapping … (1/3)

Client Server HTTP HTML User Agent mod_php TCP/IP connection 3306,…

…continued… (2/3)

Client Server HTTP HTML Embedded Objects User Agent mod_php TCP/IP connection 3306,…

…continued(3/3)

Client Server HTTP HTML +JS User Agent mod_php TCP/IP connection 3306,…

3

rd

solution: Web Api and mobile app

Web API (cloud) init • Send the current state • Reply with the

new state

Interface (remote functions) backend

front end

New trends: Mobile cloud computing

code/data offloading

result

• wi-fi direct (comm. feature) • reflection (language feature) • security aspects

• application partitioning • subtasks allocation

• DTN and social behavior

• voice recognition • pattern recognition • augmented reality • games (e.g., chess) • …

computation •Goal: To reduce the execution time

Mobile cloud computing*

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Task offloading to other mobile device

(*) Mobile-to-Mobile Opportunistic Task Splitting and Offloading Beraldi et al., WiMob15

Mobile applications and QR code

QR-code QR-reader

Internet

Another examples: media are changing

Summary

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Cloud can be exploited in mobile apps in different ways

• Data synchronization among devices

• Data storage system

• Access functionalities provided via an interface (SaaS)

• Mobile cloud computing

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… but, cloud computing in itself is a set of technologies that

can be used alone (without connections to a mobile app)

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In addition, mobile apps can exploit new dimensions

• Social (e.g, who is near me with the same interests)

• Context-awareness (e.g., Google maps)

• Sensors (NFC,GPS,…)

• Augmented reality

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Moreover, mobile apps (as fixed apps) can exploit a lot of