IELM 511: Information System design
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IELM 511: Information System design. Introduction. Part 1. ISD for well structured data – relational and other DBMS. Info storage (modeling, normalization) Info retrieval (Relational algebra, Calculus, SQL) DB integrated API’s. Part 2. ISD for systems with non-uniformly structured data.

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IELM 511: Information System design

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IELM 511: Information System design

Introduction

Part 1. ISD for well structured data – relational and other DBMS

Info storage (modeling, normalization)

Info retrieval (Relational algebra, Calculus, SQL)

DB integrated API’s

Part 2. ISD for systems with non-uniformly structured data

Basics of web-based IS (www, web2.0, …)

Markup’s, HTML, XML

Design tools for Info Sys: UML

Part III: (subset of)

API’s for mobile apps

Security, Cryptography

IS product lifecycles

Algorithm analysis, P, NP, NPC


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Agenda

Need and applications of mobile apps

Problems in development of mobile apps

Case study: Google Android

Concluding remarks


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Mobile computing: Needs and Applications

Location and guidance systems, e.g.

GPS and Map-based services

Logistics services, e.g.

FedEx/DHL delivery tracking/receiving systems

Ubiquitous computing, e.g.

Internet fridge, Home device controls, Building security systems


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Mobile computing: Issues

Hardware:

Lower Bandwidth (wireless bandwidth is lower than wired) 

Data transfer is slower (e.g. poor performance of iPhone GPS)

Limited battery power 

Restricted to low power consumption apps

Reliability 

Wireless service (cells) do not cover all areas, e.g. Mfg Sys Lab !

Human Computer Interface (HCI) 

For small mobile devices, e.g. phones/PDAs, user-interface is an issue

Software:

Multi-purpose devices 

Multi-tasking/threading, prioritizing and switching between processes


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Common Mobile Phone OS’s

Symbian OS (used by Nokia, Sony-Ericsson, …)

- Pre-emptive multi-tasking

- Closed source, Uses C++, Supports Java,

- App development requires certification

RIM Blackberry (used by Blackberry phones)

- Simple GUI, Optimized applications and HCI for email

Windows mobile (used by Samsung, AT&T, LG, Palm Treo)

- GUI emulates windows on PC

- Software development kit (SDK) is free for students, uses Visual C++, .NET

iPhone OS (used by Apple iPhones)

- Based on Apple OS X

- GUI: user friendly, touch-screen only (no keypad support)

Google Android (used by Google phone, HTC, …)

- Linux-based OS, Open source !

- SDK is free, uses Java


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Comparing mobile apps with desktops..

What differentiates mobile apps from desktop apps ?

- Networked applications must deal with cellular communications

- Mobile OS (and apps have very limited resources:

Smaller size, Less RAM, Slower low energy CPU, Limited graphics,

RAM is smaller, …

mobile multimedia formats and file formats are different

- Mobile I/O systems are quite different from desktop ones

Touch-screen based, phone-keys based, reduced keyboard-based, …


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Mobile Application Development: Case study - Android

Steps in Android Application development:

Download and install SDK

Develop the application: Eclipse IDE (Java, SQLite, XML)

Test the application: Android emulator

Register with Google (US$ 25)

Upload your application to Google App Store


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Android OS Architecture

Phone users

App developers

Programmers

Hardware developers


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Resources:

Data, sound files, images

data

java

code

java

code

mp3

# library calls

Structure of an Android Application

Android apps are stored in ‘packages’

aapt

MyApp.apk

Android OS is multi-processing, multi-threading  multiple processes can

be running on the device at the same time.

Processes can communicate w/ the OS, and also can communicate w/ each other


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Logical structure and life of an Android Application

An Android app is composed of a set of components

- Each component does a well defined activity

- Due to multi-tasking, multiple components could be doing something

at the same time

- An app may use a component from some other app, and/or it may

allow other apps to use some of its components

When an app is executed, Android creates a “virtual computer” in which

the process runs  each process is isolated from others.

This is implemented via the DalVik Virtual Machine [Java Virtual Machine]

 security

However, processes can share data with each other via special components

called ‘content providers’


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Android components: Activities

Activity is a sequence of related actions

Each activity presents a visual interface to the user

Each activity is derived from base class Activity

Each activity owns a View which controls a rectangular window;

Child views (controlling sub-rectangles) can be derived from parents;

Views are used to create images, icons, buttons, etc.

Examples:

The “Contacts” application may have an activity that displays a

scrolling list of all contacts listed by last name.

The “Calculator” app may have an activity that displays a numeric keyboard

and buttons for numeric operations, etc. and awaits inputs from the user.


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Android API – activity control loop

Colored ovals: states of the activity

Grey rectangles: callback methods written by developer

source: developer.android.com


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Android components: Services

Service is an activity that runs in the background  no visual interface

Each activity is derived from base class Service

Example:

A common example of a service is an mp3 player that may run in the

background as the user may be involved with some activity of another

app, e.g. web browser.


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Android API – service control loop

Colored ovals: states of the service

Grey rectangles: callback methods written by developer

NOTE:

Typically, a service may be created, say, by an activity;

Alternatively, a service may be started and running in some

other context, and can announce its interface to other activities –

in this case, the activity may just connect itself to the service,

in Android, this is called “bind”-ing to the service.

source: developer.android.com


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Android components: Broadcast receivers

Broadcast receivers are similar to interrupt handlers in normal OS

BRs run in the background, listening for interrupts generated by other apps

An application may have one or more BR’s to handle interrupts.

Examples of interrupts:

- Incoming phone call

- User changed language setting

- Battery is low

- User has transited from one time zone to different one


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Android components: Content providers

Content providers make some subset of an application’s data available

to other apps when requested

Content providers are the only mechanism for apps to share data.


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Android application process

Process can be multi-threaded  Android apps do not have a C-style “main”.

Activities, services, broadcast receivers: activated by messages called intents.

Content providers: activated by special objects called ContentResolvers.

Depending on the state of the application, and the user’s actions, the app

may start (or terminate) some activity, or service, etc.

 Before Android can start an application component, it must know

the name, location, and input types of the component  The manifest

<?xml version="1.0" encoding="utf-8"?>

<manifest package="com.example.android.notepad" …>

<application android:icon="@drawable/app_notes" android:label="@string/app_name" >

<activity android:name="NotesList" android:label="@string/title_notes_list">

<intent-filter> <action android:name="android.intent.action.MAIN" /> …

</intent-filter>

<intent-filter>

<action android:name="android.intent.action.VIEW" />

<action android:name="android.intent.action.EDIT" />

<action android:name="android.intent.action.PICK" /> …

</intent-filter>

</activity>

</application>

</manifest>

Notepad app

(partial manifest)


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Views in Android

Most activities will present a ‘view’ to the user, either to display some

graphics, or to get some user-input.

Thus each activity can create (instances) of one or more views. Each

view has some graphical objects that either fill the complete screen,

or a part of the screen.

Each object in a view, i.e. the layout, is also described in XML

<?xml version="1.0" encoding="utf-8"?>

<view xmlns:android="http://schemas.android.com/apk/res/android"

class="com.example.android.notepad.NoteEditor$LinedEditText"

android:id="@+id/note"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:background="@android:color/transparent"

android:padding="5dip"

android:scrollbars="vertical"

android:fadingEdge="vertical"

android:gravity="top"

android:textSize="22sp"

android:capitalize="sentences"

/>

Notepad app

(layout of Note-Editor)


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Android app development: summary

The basic steps of developing an android app:

- Develop UML class diagrams, activity diagrams, use-case diagrams …

- Identify the activities, services, …

- For each activity, decide the GUI and design it, store as resources.

- Use the IDE (e.g. Eclipse), and program the Java code for each class

- Test & debug the code using the android emulator

- Upload the code on the mobile device.


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Brief concluding remarks

Mobile Operating Systems are in some ways similar to desktop OS,

but there are several differences in details, and in usage.

Mobile app development process is almost similar to normal app development,

but issues such as compiled code size, memory usage and algorithm efficiency

are much more important.

Several modern mobile OS’s are using xml as an integral part the programming

language – e.g. Android (manifest, view layout), Palm Pre OS, …


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References and Further Reading

Mobile OS wikipedia

Google android developer site

Next: Project completion, Exam!


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Case study: Hangman-style – ‘Save the bird’ game

We consider a game similar to the popular ‘Hangman’ game, with the

main difference being in the graphics (6 wrong guesses  shark eats bird)


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