Android Full Seminar Report

8/13/2019 Android Full Seminar Report

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1. INTRODUCTION

Android is a software stack for mobile devices that includes an operating system,

middleware and key applications. Android is a software platform and operating system for

mobile devices based on the Linux operating system and developed by Google and the Open

Handset Alliance. t allows developers to write managed code in a !ava"like language that

utili#es Google"developed !ava libraries, but does not support programs developed in native

code.

$he unveiling of the Android platform on % &ovember '(() was announced with the

founding of the Open Handset Alliance, a consortium of *+ hardware, software and telecom

companies devoted to advancing open standards for mobile devices. hen released in '((-,most of the Android platform will be made available under the Apache free"software and

open"source license.

1.1. THE BIRTH OF ANDROID

1.1.1. Google Acquires Android Inc.

n !uly '((%, Google ac uired Android nc., a small startup company based in /aloAlto, 0A. Android1s co"founders who went to work at Google included Andy 2ubin

3co"founder of 4anger5, 2ich 6iner 3co"founder of ildfire 0ommunications, nc5,

&ick 7ears 3once 8/ at $"6obile5, and 0hris hite 3one of the first engineers at

eb$85. At the time, little was known about the functions of Android nc. other

than they made software for mobile phones.

At Google, the team, led by 2ubin, developed a Linux"based mobile device O7

which they marketed to handset makers and carriers on the premise of providing a

flexible, upgradeable system. t was reported that Google had already lined up a

series of hardware component and software partners and signaled to carriers that it

was open to various degrees of cooperation on their part.

1.1.2. Open H ndse! Alli nce Founded

On % &ovember '((), the Open Handset Alliance, a consortium of several

companies which include Google, H$0, ntel, 6otorola, 9ualcomm, $"6obile,

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3.4 @5 that is created through build time post processing. 0onversion between

!ava classes and .4 @ format is done by included BdxC tool.

1.2.+. In!egr !ed Bro#ser

Google made a right choice on choosing ebDit as open source web browser. $hey

added a two pass layout and frame flattening. $wo pass layout loads a page

without waiting for blocking elements, such as external 077 or external

!ava7cript and after a while renders again with all resources downloaded to the

device. ;rame flattening converts founded frames into single one and loads

into the browser. $hese features increase speed and usability browsing the

internet via mobile phone.

1.2.,. Op!i%i-ed Gr p*ics

As Android has '4 graphics library and *4 graphics based on OpenGL 7

:.(, possibly we will see great applications like Google arth and spectacular

games like 7econd Life, which come on Linux version. At this moment, the

shooting legendary *4 game 4oom was presented using Android on the mobile

phone.

1.2. . $/0i!e

xtremely small 3E%((kb5 relational database management system, which is

integrated in Android. t is based on function calls and single file, where all

definitions, tables and data are stored. $his simple design is more than suitable for a

platform such as Android.

1.2. . H ndse! 0 ou!s

$he platform is adaptable to both larger, 8GA, '4 graphics library, *4 graphics

library based on OpenGL 7 :.( specifications, traditional smart phone layouts. An

underlying '4 graphics engine is also included. 7urface 6anager manages access to

the display subsystem and seamlessly composites '4 and *4 graphic layers from

multiple applications

1.2.3. D ! $!or ge

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79Lite is used for structured data storage .79Lite is a powerful and lightweight

relational database engine available to all applications.

1.2.4. Connec!i'i!

Android supports a wide variety of connectivity technologies including G76,

046A, =luetooth, 4G , 84O, *G and i";i.

1.2.5. )ess ging

767, 667, and @6// are available forms of messaging including threaded text

messaging.

1.2.16. 7e8 Bro#ser

$he web browser available in Android is based on the open"source ebDit

application framework. t includes Lib eb0ore which is a modern web browser

engine which powers both the Android browser and an embeddable web view.

1.2.11. 9 ' (ir!u l ) c*ine

7oftware written in !ava can be compiled into 4alvik bytecodes and executed in the4alvik virtual machine, which is a speciali#ed 86 implementation designed for

mobile device use, although not technically a standard !ava 8irtual 6achine.

1.2.12. )edi $uppor!

Android will support advanced audio?video?still media formats such as 6/ G"+,

H.'>+, 6/*, and AA0, A62, !/ G, /&G, G ;.

1.2.1+. Addi!ion l H rd# re $uppor!

Android is fully capable of utili#ing video?still cameras, touchscreens, G/7,

compasses, accelerometers, and accelerated *4 graphics.

1.2.1,. De'elop%en! En'iron%en!

ncludes a device emulator, tools for debugging, memory and performance profiling,

a plugin for the clipse 4 . $here are a number of hardware dependentfeatures, for instance, a huge media and connections support, G/7, improved

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support for 0amera and simply G76 telephony. A great work was done for the

developers to start work with Android using device emulator, tools for

debugging and plugin for clipse 4 .

2. DETAI0ED DE$CRI:TION OF THE TO:IC2.1. O:ERATION

2.1.1. Android Run!i%e

Android includes a set of core libraries that provides most of the functionality

available in the core libraries of the !ava programming language. very Android

application runs in its own process, with its own instance of the 4alvik virtual

machine. 4alvik has been written so that a device can run multiple 86s efficiently.

$he 4alvik 86 executes files in the 4alvik xecutable 3.dex5 format which is

optimi#ed for minimal memory footprint. $he 86 is register"based, and runs classes

compiled by a !ava language compiler that have been transformed into the .dex format

by the included FdxF tool.$he 4alvik 86 relies on the Linux kernel for underlying

functionality such as threading and low"level memory management.

2.1.2. 0inu;


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2.2. ARCHITECTURE

$he following diagram shows the ma or components of the Android operating system.

ach section is described in more detail below.

Figure 2.1 = Architecture Of Android

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byte code from . ar to .dex file, after this byte code becomes much more efficient to

run on the small processors.

Figure 2.2 = 0onversion from . ava to .dex file

As the result, it is possible to have multiple instances of 4alvik virtual machine

running on the single device at the same time. $he 0ore libraries are written in !ava

language and contains of the collection classes, the utilities, O and other tools.

2.2.,. Applic !ion Fr %e#or&

After that, there is Application ;ramework, written in !ava language. t is a toolkit

that all applications use, ones which come with mobile device like 0ontacts or 767

box, or applications written by Google and any Android developer. t has several

components.

$he Activity 6anager manages the life circle of the applications and provides a

common navigation back stack for applications, which are running in different

processes. $he /ackage 6anager keeps track of the applications, which are installed

in the device. $he indows 6anager is !ava programming language abstraction on

the top of lower level services that are provided by the 7urface 6anager.

$he $elephony 6anager contains of a set of A/ necessary for calling applications.

0ontent /roviders was built for Android to share a data with other applications, for

instance, the contacts of people in the address book can be used in other applications

too. $he 2esource 6anager is used to store locali#ed strings, bitmaps, layout file

descriptions and other external partsof the application. $he 8iew 7ystem generates a

set of buttons and lists used in < . Other components like &otification manager is

used to customi#e display alerts and other functions.

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2.2. . Applic !ion 0 er

At the top of Android Architecture we have all the applications, which are used by

the final user. =y installing different applications, the user can turn his mobile phone

into the uni ue, optimi#ed and smart mobile phone. All applications are written

using the !ava programming language.

2.+. DE(E0O:ING A::0ICATION$

2.+.1. Applic !ion Building Bloc&s

e can think of an Android application as a collection of components, of various

kinds. $hese components are for the most part uite loosely coupled, to the degree

where you can accurately describe them as a federation of components rather than a

single cohesive application.

Generally, these components all run in the same system process. t1s possible 3and

uite common5 to create multiple threads within that process, and it1s also possible to

create completely separate child processes if you need to. 7uch cases are pretty

uncommon though, because Android tries very hard to make processes transparent to

your code.

Google provides three versions of 74D for indows, for 6ac O7@ and one for

Linux.$he developer can use Android plugin for clipse 4 or other 4 s such as

intelli!.;irst step for Android developer is to decompose the prospective application

into the components, which are supported by the platform. $he ma or building

blocks are theseI

Activity

ntent 2eceiver

7ervice

0ontent /rovider

'.*.:.:. Activity

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es!.;%l

$he Android6anifest.xml file is the control file that tells the system what to do with

all the top"level components 3specifically activities, services, intent receivers, and

content providers described below5 you1ve created. ;or instance, this is the FglueF

that actually specifies which ntents your Activities receive.

A developer should predefine and list all components, which he wants to use in the

specific Android6anifest.xml file. t is a re uired file for all the applications and

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is located in the root folder. t is possible to specify all global values for the package,

all the components and its classes used, intent filters, which describe where and

when the certain activity should start, permissions and instrumentation like

security control and testing.

Here is an example of Android6anifest.xml fileI

:. N xml versionPF:.(F encodingPFutf"-F Q

'. Nmanifest xmlnsIandroidPFhttpI??schemas.android.com?apk?res?androidF

*. packagePFdk.mdev.android.helloFQ

+. Napplication androidIiconPFRdrawable?iconFQ

%. Nactivity classPF.HelloAndroidF androidIlabelPFRstring?appSnameFQ

>. Nintent"filterQ

). Naction androidIvaluePFandroid.intent.action.6A &F ?Q

-. Ncategory androidIvaluePFandroid.intent.category.LAec cle

n Android, every application runs in its own process, which gives better

performance in security, protected memory and other benefits. $herefore, Android is

responsible to run and shut down correctly these processes when it is needed.

t is important that application developers understand how different application

components 3in particular Activity, 7ervice, and =roadcast2eceiver5 impact the

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lifetime of the application1s process. &ot using these components correctly can result

in the system killing the application1s process while it is doing important work.

$o determine which processes should be killed when low on memory, Android

places each process into an Fimportance hierarchyF based on the components

running in them and the state of those components. $hese process types are 3in order

of importance5.

:. A foreground process is one that is re uired for what the user is currently doing.

8arious application components can cause its containing process to be

considered foreground in different ways. A process is considered to be in the

foreground if any of the following conditions holdI

i. t is running an Activity at the top of the screen that the user is

interacting with 3its on2esume35 method has been called5.

ii. t has a =roadcast2eceiver that is currently running 3its

=roadcast2eceiver.on2eceive35 method is executing5.

iii. t has a 7ervice that is currently executing code in one of its callbacks

37ervice.on0reate35, 7ervice.on7tart35, or 7ervice.on4estroy355.

$here will only ever be a few such processes in the system, and these will only

be killed as a last resort if memory is so low that not even these processes can

continue to run. Generally, at this point, the device has reached a memory paging

state, so this action is re uired in order to keep the user interface responsive.

'. A visible process is one holding an Activity that is visible to the user on"screen

but not in the foreground 3its on/ause35 method has been called5. $his may

occur, for example, if the foreground Activity is displayed as a dialog that allows

the previous Activity to be seen behind it. 7uch a process is considered

extremely important and will not be killed unless doing so is re uired to keep all

foreground processes running.

*. A service process is one holding a 7ervice that has been started with the

start7ervice35 method. $hough these processes are not directly visible to the user,

they are generally doing things that the user cares about 3such as background

mp* playback or background network data upload or download5, so the system

will always keep such processes running unless there is not enough memory to

retain all foreground and visible process.

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+. A background process is one holding an Activity that is not currently visible to

the user 3its on7top35 method has been called5. $hese processes have no direct

impact on the user experience. /rovided they implement their Activity life"cycle

correctly 3see Activity for more details5, the system can kill such processes at

any time to reclaim memory for one of the three previous processes types.


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Figure 2.+ = ;lowchart 7howing $he Lifecycle Of An Activity

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n the following example we will display a process flow from the Android

7ystem point of view to get a clear idea how the applications behave. Let

assume the

Figure 2.,

/ossible scenarioI A user talks to his friend via mobile phone and he is asked

to browse the internet 3a talk is hold for a moment5, find a picture of him in his

/icasa Album, send it via mail back to his friend and resume a talk.

n this situation, there are + different applications and + different processes

running, but from the user point of view none of them are important, as

Android manages 0/< work and memory usage by itself. t means the user can

travel through the applications forward and back without thinking about how

much memory is left or which processes are run at the time.;irstly, as the user

is talking to his friend, a specific $alk application is opened, which contains the

activity manager. n the following stack we can see two processes running, the

main system process and $alk application process. 6oreover, before going to

eb =rowser application, the system saves a $alk state $ in order to remember

that processI

Figure 2.

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At this point, as a user holds a talk and opens a web browser, the system creates

a new process and new web browser activity is launched in it. Again, the state

of the last activity is saved 3 5I

Figure 2.

After that, the user browses the internet, finds his picture in /icasa album and

saves it to particular folder. He does not close a web browser, instead he opens

a folder to find saved picture. $he folder activity is launched in particular

processI

Figure 2.3

At this point, the user finds his saved picture in the folder and he creates a

re uest to open an mail application. $he last state ; is saved. &ow assume

that the mobile phone is out of the memory and there is no room to create a

new process for mail application. $herefore, Android looks to kill a process.

t can not destroy ;older process, as it was used previously and could be reused

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again, so it kills eb =rowser process as it is not useful anymore and locates a

new mail process insteadI

Figure 2.4

$he user opens mail application and sends a picture to his friend via email. &ow he

wants to go back to the $alk application and to resume a talk to his friend. =ecause

of the previously saved states, this work is done fast and easily. n this example,

mail application is popped out and the user sees a previous ;older applicationI

Figure 2.5

&ext, the user goes back to eb =rowser application.


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Figure 2.16

and finallyI

Figure 2.11

&ow the user comes back to the $alk application and resumes his talk with his

friend.=ecause of the saved states, going back procedure is fast and useful, becauseit remembers previous activities and its views.

$his example shows, that it does not matter how many applications and processes

are active or how much available memory is left, Android it manages fast and

without a user interaction.

2.+.,. Applic !ion Fr %e#or&

4evelopers have full access to the same framework A/ s used by the core

applications. $he application architecture is designed to simplify the reuse of:- " / a g e


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components any application can publish its capabilities and any other application

may then make use of those capabilities 3sub ect to security constraints enforced by

the framework5. $his same mechanism allows components to be replaced by the

user.

+, 6/*, AA0, A62,

!/G, and /&G

7urface 6anager " manages access to the display subsystem and

seamlessly composites '4 and *4 graphic layers from multiple

applications .

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Lib eb0ore " a modern web browser engine which powers both the

Android browser and an embeddable web view

7GL " the underlying '4 graphics engine

*4 libraries " an implementation based on OpenGL 7 :.( A/ s the

libraries use either hardware *4 acceleration 3where available5 or the

included, highly optimi#ed *4 software rasteri#er

;ree$ype " bitmap and vector font rendering

79Lite " a powerful and lightweight relational database engine available

to all applications

2.,. $OFT7ARE DE(E0O:)ENT

$he feedback on developing applications for the Android platform has been mixed.

ssues cited include bugs, lack of documentation, inade uate 9A .$he first publicly

available application was the 7nake game.

2.,.1. $o>!# re De'elop%en! &i!

t includes development and debugging tools, a set of libraries, a device emulator,

documentation, sample pro ects, tutorials, and ;A9s . 2e uirements also include

!ava 4evelopment Dit, Apache Ant, and /ython '.' or later. $he only officially

supported integrated development environment 3 4 5 is clipse *.' or later, through

the Android 4evelopment $ools /lugin, but programmers can use command line

tools to create, build and debug Android applications.

: r!i l 0is!ing o> Open H ndse! Alli nce : r!icip n!sCore Tec*nolog (endors

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http://en.wikipedia.org/wiki/FAQhttp://en.wikipedia.org/wiki/FAQ


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Figure 2.12

2. . $ECURIT? I$$UE$

Android mobile phone platform is going to be more secure than Apple s i/hone or any

other device in the long run. $here are several solutions nowadays to protect Google

phone from various attacks. One of them is security vendor 6cAfee, a member of Linux

6obile 3Li6o5 ;oundation. $his foundation oins particular companies to develop an

open mobile"device software platform. 6any of the companies listed in the Li6o

;oundation have also become members of the Open Handset Alliance 3OHA5.

As a result, Linux secure coding practice should successfully be built into the Android

development process. However, open platform has its own disadvantages, such as

source code vulnerability for black"hat hackers. n parallel with great opportunities for

mobile application developers, there is an expectation for exploitation and harm.

7tealthy $ro ans hidden in animated images, particular viruses passed from friend to

friend, used for spying and identity theft, all these threats will be active for a long run.

Another solution for such attacks is 76obile 7ystems mobile package. 7ecurity7hield J an integrated application that includes anti"virus, anti"spam, firewall and other mobile

protection is up and ready to run on the Android operating system. 0urrently, the main

problem is availability for viruses to pose as an application and do things like dial phone

numbers, send text messages or multi"media messages or make connections to the

nternet during normal device use. t is possible for somebody to use the G/7 feature to

track a person s location without their knowledge. Hence 76obile 7ystems is ready to

notify and block these secure alerts. =ut the truth is that it is not possible to secure your

mobile device or personal computer completely, as it connects to the internet. And

neither the Android phone nor other devices will prove to be the exception.

2. . CO):ARI$ON

2. .1. $pecul !ions 7i!* Cellul r C rriers

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n contrast, &okia is buying companies and dumping cash into development, while

Google is releasing an open platform hoping the applications and services will build

themselves with the help of a strong developer community, development contests

and large alliance of grand companies.

4espite of this, &okia is ready to combat whatever Google has to throw with Google

Android in '((-. Another company Apple has already stroked the market with

i/hone and its closed operating system. Accordingly, i/hone in the


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$he diagram below shows the study, which was conducted in 7eptember '(() via an

online *(" uestion survey of %((


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$hough the location is not very precise, the mobile phone is able to broadcast it

automatically. At that point the text can be connected to users location and create a

list of preferences for each place the user fre uently visits.


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Figure 2.1, = ;igure describes Google s mobile focused payments called G/ay

4escribed as Fa computer"implemented method of effectuating an electronic on"line

payment,F the system mentioned in the patent application is similar to existing

mobile payment services.

$hese services like mobile version of /ay/al have been available for some time but

have had little success bursting with merchants and with customers. $he main

difference between existing mobile payment systems and G/ay is, of course, that

G/ay is created by Google and will be easily adopted by Android /latform. $he

more issues regarding Gpay are yet to be released.

2. . . 7* ! % &es Android speci l

$here are already many mobile platforms on the market today, including 7ymbian,

i/hone, indows 6obile, =lack=erry, !ava 6obile di"tion, Linux 6obile 3Li6o5,

and more.

hile some of its features have appeared before, Android is the Wrst environment

that combinesI

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A truly open, free development platform based on Linux and open

source. Handset makers like it because they can use and customi#e

the platform without paying a royalty. 4evelopers like it because they

know that the platform Bhas legsC and is not locked into any onevendor that may go under or be ac uired.

A component"based architecture inspired by nternet mash"ups.

/artsof one application can be used in another in ways not

originallyenvisioned by the developer. Xou can even replace built"in

components with your own improved versions. $his will unleash a

new round of creativity in the mobile space.

$ons of built"in services out of the box. Location based services use

G/7 or cell tower triangulation to let you customi#e the user

experience depending on where they are. A full"powered 79L

database lets you harness the power of local storage for occasionally

connected computing and synchroni#ation. =rowser and 6ap views

can be embedded directly in your applications. All these built"in

capabilities help to raise the bar on functionality while loweringyourdevelopment costs.

Automatic management of the application life cycle. /rograms

areisolated from each other by multiple layers of security, which will

provide a level of system stability not seen before in smart

phones.$he end user will no longer have to worry about what

applications are active, or close some programs so that others can run.

Android is optimi#ed for low"power, low"memory devices in a

fundamental way that no previous platform has attempted.

High uality graphics and sound. 7mooth, anti"aliased '4 vector

graphics and animation inspired by ;lash is melded with *4

accelerated OpenGL graphics to enable new kinds of games and

business applications. 0odecs for the most common industry standard

audio and video formats are built right in, including H.'>+ 3A805,6/*, and AA0.

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/ortability across a wide range of current and future hardware.All

your programs are written in !ava and executed by Android s 4alvik

virtual machine so your code will be portable across A26,x->, and

other architectures. 7upport for a variety of input methods is includedsuch as keyboard, touch, tilt, camera, voice, and trackball.


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A/ , external connectivity 3(, because A/ s simply do not seem to be exposed to !'6 . A user may

find difficulties synchroni#ing Google 0alendar with his device " nobody seems to

have been able to figure out how to make the !'6 calendar interfaces work

correctly on 7>(. $here are lots of problems with !ava applications on 7>(, even

though 7>( probably has one of the best !ava implementations.

Android fills a void in !ava 6obile applications by providing A/ to build richer

applications " more useful for 7mart /hones which contain the ability to provide

these types of functionalities. f !'6 filled every void, Android as an A/ wouldn1t

be needed 3though Android as an O7 could still fill a void5.

Google has written its own virtual machine for Android most likely as a way to get

around licensing issues with 7un. However, Android does not include a complete

and compliant !ava stack 3neither !6 nor !7 5 only a subset and therefore it is

technically not the !ava platform, it ust looks a lot like it.

2. .4. Openness O> T*e :l !>or%

$he open source school of thought implies that differentiation and competitive

advantage come from innovation on top of the underlying platform rather than the

platform itself. $he robustness and scalability of the platform is secured by the

community s stewardship, and open access to a central repository of updated code.

=eyond this, a strong third"party development environment and softwaredevelopment kit 374D5 are critical to attracting innovation.

BOpenC is an invariably sub ective term. 7ymbian and 6icrosoft can claim a degree

of openness for their mobile platforms, for example, but ultimate control of A/

access and source code remains with a single entity. On the contrary, as Google has

pointed out, there s nothing keeping any of the alliance members from using

Android to build a XahooY Go phone.

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6otorola has had some success delivering high"volume Linux"based devices such as

the 6ing and 2AZ2 to market. =ut mobile Linux initiatives have failed to scale

on the basis of attractiveness to third"party developers it s been supply"push with

the development focus in !ava 6 or other application framework components.

mportantly, Android includes almost the entirety of the applications"related

software stack, less key technical pieces such as telephony protocol stacks, which

are left to silicon vendors. Android bundles critical components such as a Linux

kernel from ind 2iver, various optimi#ed graphics engines, codecs, notification

software, a Bclean roomC !86 implementation, and the DH$6L open source

browser. $he latter forms the basis of Apple s 7afari and &okia s 7>( offerings.

2. .5. Ad' n! ges

Open Android allows you to access core mobile device functionality through

standard A/ calls.

All applications are e ual Android does not differentiate between the phone1s

basic and third"party applications "" even the dialer or home screen can be

replaced.

=reaking down boundaries 0ombine information from the web with data on the

phone "" such as contacts or geographic location "" to create new user

experiences.

;ast and easy development $he 74D contains what you need to build and run

Android applications, including a true device emulator and advanced debugging

tools.

2. .16. Dis d' n! ges

7ecurity 6aking source code available to everyone inevitably invites the

attention of black hat hackers.

Open 7ource A disadvantage of open"source development is that anyone can

scrutini#e the source code to find vulnerabilities and write exploits.

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Login /latform doesn1t run on an encrypted file system and has a vulnerable

log"in.

ncompetence " Google s dependence on hardware and carrier partners puts the

final product out of their control.

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+. CONC0U$ION AND FUTURE $CO:E

Android has been critici#ed for not being all open"source software despite what was

announced by Google. /arts of the 74D are proprietary and closed source, and some believe this is so that Google can control the platform. 7oftware installed by end"users

must be written in !ava, and will not have access to lower level device A/ s. $his

provides end"users with less control over their phone1s functionality than other free and

open source phone platforms, such as Open6oko.

ith all upcoming applications and mobile services Google Android is stepping into

the next level of 6obile nternet. Android participates in many of the successful open

source pro ects. $hat is, architect the solution for participation and the developers will

not only come but will play well together. $his is notable contrast with Apple and

other companies, where such architecture of participation is clearly belated.

$he first Android based official devices may well be launched sometime in the early

half of '((M. Obviously, that1s an age away when it comes to handset design, and

Android may well find itself competing against the forthcoming &okia touch screen

phones and maybe even the i/hone '.

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Android Full Seminar Report

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