1 Designing Inputs, Outputs, and Controls. 2 Final Exam Chapters 1 to 12 and 14 and 15(5 th Edition) 20 multiple choices 3 short questions OO diagram.

1

Designing Inputs, Outputs, and Controls

2

Final Exam

• Chapters 1 to 12 and 14 and 15(5th Edition)

• 20 multiple choices

• 3 short questions

• OO diagram– Use Case– Class– Sequence

3

Overview• This chapter focuses on system interfaces, system

outputs, and system controls that do not require much human interaction

• Many system interfaces are electronic transmissions or paper outputs to external agents

• System developers need to design and implement integrity and security controls to protect system and its data

• Outside threats from Internet and e-commerce are growing concern

4

Identifying System Interfaces• System interfaces are broadly defined as

inputs or outputs with minimal or no human intervention– Inputs from other systems (messages, EDI)– Highly automated input devices such as

scanners– Inputs that are from data in external databases– Outputs to external databases– Outputs to other systems

5

Full Range of Inputs and Outputs

6

eXtensible Markup Language (XML)

• Extension of HTML that embeds self-defined data structures in textual messages

• Transaction that contains data fields can be sent with XML codes to define meaning of data fields

• XML provides common system-to-system interface

• XML is simple and readable by people

• Web services is based on XML to send business transactions over Internet

7

System-to-System Interface Based on XML

Before XML This would be something like:RM010989;william jones;120 Roundabout Road;Los Angeles ….

8

Design of System Inputs

• Identify devices and mechanisms used to enter input– High-level review of most up-to-date methods to

enter data

• Identify all system inputs and develop list of data content for each input– Provide link between design of application software

and design of user and system interfaces

• Determine controls and security necessary for each system input

9

Input Devices and Mechanisms

• Capture data as close to original source as possible

• Use electronic devices and automatic entry whenever possible

• Avoid human involvement as much as possible

• Seek information in electronic form to avoid data re-entry

• Validate and correct information at entry point

10

Prevalent Input Devices to Avoid Human Data Entry

• Magnetic card strip readers• Bar code readers• Optical character recognition readers and

scanners• Radio-frequency identification tags• Touch screens and devices • Electronic pens and writing surfaces• Digitizers, such as digital cameras and digital

audio devices• Sensors !!

Identifying System Interfaces– Real-time connections (both input and output)– Sensors !!

• 30 billion RFID tags and 4.6 billion camera phones are used around the world today. In addition, 200 million smart meters to be operated in 2014. Moreover, there were 2 billion people on web in 2011

»

» BIG DATA

11

Amount of new data stored varies across geography. New data stored (in Petabytes – 1M Gbytes - (PB)) by geography in 2010. New data stored is defined as the amount of available storage used in a given year [9].

12

Defining the Details of System Inputs

• Ensure all data inputs are identified and specified correctly

• Can use traditional structured models– Identify automation boundary

• Use DFD fragments• Segment by program boundaries

– Examine structure charts• Analyze each module and data couple• List individual data fields

13

Automation Boundary on a System-Level DFD

14

15

List of Inputs for Customer Support System

16

Using Object-Oriented Models• Identifying user and system inputs with OO

approach has same tasks as traditional approach• OO diagrams are used instead of DFDs and

structure charts• System sequence diagrams identify each incoming

message• Design class diagrams and sequence diagrams

identify and describe input parameters and verify characteristics of inputs

17

System Sequence Diagram for Create New Order

18

Input Messages and Data Parameters from RMO System Sequence Diagram

(Figure 14-10)

19

Designing System Outputs

• Determine each type of output

• Make list of specific system outputs required based on application design

• Specify any necessary controls to protect information provided in output

• Design and prototype output layout

• Ad hoc reports – designed as needed by user

20

Designing Reports and Statements

• Printed versus electronic• Types of output reports

– Detailed – Summary– Exception – Executive

• Internal versus external • Graphical and multimedia presentation

21

RMO Summary Report with Drill Down to the Detailed Report

22

Formatting Reports

• What is the objective of report?

• Who is the intended audience?

• What is the media for presentation?

• Avoid information overload

• Format considerations include meaningful headings, date of information, date report produced, page numbers

23

Designing Integrity Controls

• Mechanisms and procedures built into a system to safeguard it and information contained within

• Integrity controls– Built into application and database system to

safeguard information

• Security controls– Built into operating system and network

24

Objectives of Integrity Controls

• Ensure that only appropriate and correct business transactions occur

• Ensure that transactions are recorded and processed correctly

• Protect and safeguard assets of the organization– Software– Hardware– Information

25

Input Integrity Controls

• Used with all input mechanisms

• Additional level of verification to help reduce input errors

• Common control techniques– Field combination controls– Value limit controls– Completeness controls– Data validation controls

26

Database Integrity Controls

• Access controls

• Data encryption

• Transaction controls

• Update controls

• Backup and recovery protection

27

Output Integrity Controls• Ensure output arrives at proper destination and

is correct, accurate, complete, and current

• Destination controls - output is channeled to correct people

• Completeness, accuracy, and correctness controls

• Appropriate information present in output

28

Interface Design Guidelines

• Many interface design guidelines have been published to help system developers– Range from general to very specific rules

• System design standards– General principles and rules that must be followed for

the interface of any system developed by the organization

– Helps to ensure that all user interfaces are usable and all systems developed by the organization have a similar look and feel

29

Visibility and Affordance

• Two key principles to ensure good human-computer interaction (Donald Norman)– Visibility

• A key principle of HCI that states all controls should be visible (so users know its availability) and provide feedback to indicate the control is responding to the user’s actions

• E.g. a button that can be clicked should be visible, and when it is clicked should look like it has been pressed to indicate it is responding

– Affordance• A key principle of HCI that states that the appearance of any

control should suggest its functionality• e.g. a button affords clicking, a scroll bar affords scrolling, an

item in a list affords selecting etc.• Applies to objects on the desktop

30

Implications for designers

• If designers make all controls visible and clear more likely the interface will be usable

• Most users are now familiar with Windows user interface and common Windows controls– Not necessarily with Iphone/Android Interfaces

• These principles should also be applied carefully to design of web pages, where there are new types of controls and possible designs of interfaces (not standardized)

31

Eight Golden Rules

• Ben Shneiderman proposes eight underlying principles applicable to most interactive systems (and key to usability)

1. Strive for consistency2. Enable frequent users to use short cuts3. Offer informative feedback4. Design dialogs to yield closure5. Offer simple error handling6. Permit easy reversal of actions7. Support internal locus of control8. Reduce short-term memory load

32

1. Strive for Consistency

• Information arranged on forms, the names and arrangement of menus, the size and shape of icons etc. should be consistent throughout the system– This allows for many actions to become automatic

– If a new application comes along with a different way of functioning have to relearn all the basic operations

– Apple Macintosh was the first to emphasize the benefits of consistency

• Mac applications were consistent and a standards document was created for people writing Mac applications (so if you knew one you could figure out other applications easily since they were consistent)

– E.g. consistency in the menu bar for File, Edit and Format

– However some applications may not fit such guidelines and inconsistency may be useful for differentiating applications (for running and learning)

33

2. Enable Frequent Users to Use Short Cuts

• Users who work with one application all the time are willing to invest time to learn short cuts

• They begin to lose patience with long menu sequences when they know exactly what they want to do

• Short-cut keys can reduce the number of interactions for a given task

• Designers can provide macro facilities for users to create their own short cuts

• E.g. mail order entry clerks at RMO wouldn’t want long multiple menus to slow them down, but instead short-cuts would make them more productive

34

3. Offer Informative Feedback

• Every action a user takes should result in some type of feedback from the computer– Eg. If the user clicks a button it should visually change

and perhaps make a sound to indicate it has responded

– Feedback of information to the user is also important• E.g. if a mail-order clerk enters a customer ID number in the

screen, the computer should display the name and address for confirmation by the clerk

• E.g. if the clerk enters a product ID for the order, the system should display a description of the product

35

4. Design Dialogs to Yield Closure

• Each dialog with the system should be organized with a clear sequence (with a beginning and an end)– Reading one’s email

• If the system requirements are defined as events to which the system responds, each event leads to processing of one specific, well-defined activity

• Traditional approach– Each activity is defined by data flow diagrams and

structured English

• Object-oriented approach– Each activity (a use case) might be further defined as

multiple scenarios, each with a flow of events

36

5. Offer Simple Error Handling• Errors can be costly so designers must try to

prevent users from making errors– Better way is by limiting available options and

allowing user to choose from valid options at any point in the dialog

– Adequate feedback also reduces errors

• When errors occur need ways to handle it– Error messages should state specifically what is wrong

and explain how to create it– Avoid message that scare or blame the user:

e.g. “FATAL ERROR 2001”

– Also provide information that makes it easy to correct the error:

e.g. “The date of birth entered is not valid. Check to be sure only numeric characters in appropriate ranges are entered in the date of birth fields…”

37

6. Permit Easy Reversal of Actions

• Users need to feel that they can explore options and take actions that can be canceled or reversed easily

• Allows users to learn about the system by exploring

• If they make a mistake, they can cancel the action• Should include cancel buttons on all dialog boxes• Also if user is going to delete something

substantial (e.g. a file) the system should ask the user to confirm the action

38

7. Support Internal Locus of Control

• Experienced users want to feel they are in charge of the system and the system responds to them

• They should not be forced to do anything or made to feel the system is controlling them

• Much of this “comfort” and control is provided by the wording of prompts and messages

• Writing out a dialog can help to lead to such a design

39

8. Reduce Short-Term Memory Load

• People have short-term memory limitations– People remember only about seven chunks of

information at a time

– Interface designer cannot assume the user will remember anything from form to form, or dialog box to dialog box

– If user has to stop and ask “Now what was the filename? The customer ID?” then the design is placing a burden on the user’s memory

40

Integrity Controls to Prevent Fraud

• Three conditions are present in fraud cases

– Personal pressure, such as desire to maintain extravagant lifestyle

– Rationalizations, including “I will repay this money” or “I have this coming”

– Opportunity, such as unverified cash receipts

• Control of fraud requires both manual procedures and computer integrity controls

41

Fraud Risks and Prevention Techniques

42

Designing Security Controls• Security controls protect assets of organization from all

threats

– External threats such as hackers, viruses, worms, and message overload attacks

• Security control objectives

– Maintain stable, functioning operating environment for users and application systems (24 x 7)

– Protect information and transactions during transmission outside organization (public carriers)

43

Security for Access to Systems• Used to control access to any resource

managed by operating system or network

• User categories– Unauthorized user – no authorization to access– Registered user – authorized to access system– Privileged user – authorized to administrate system

• Organized so that all resources can be accessed with same unique ID/password combination

44

Users and Access Roles to Computer Systems

45

Managing User Access• Most common technique is user ID / password• Authorization – Is the user permitted to access?• Access control list – users with rights to access• Authentication – Is the user who they claim to be?• Smart card – computer-readable plastic card with

embedded security information• Biometric devices – keystroke patterns,

fingerprinting, retinal scans, voice characteristics

46

Data Security• Data and files themselves must be secure

• Encryption – primary security method– Altering data so unauthorized users cannot view

• Decryption – Altering encrypted data back to its original state

• Symmetric key – same key encrypts and decrypts

• Asymmetric key – different key decrypts

• Public key – public encrypts; private decrypts

47

Symmetric Key Encryption

Systems Analysis and Design in a Changing World, 4th Edition

48

Asymmetric Key Encryption

49

Digital Signatures and Certificates

• Encryption of messages enables secure exchange of information between two entities with appropriate keys

• Digital signature encrypts document with private key to verify document author

• Digital certificate is institution’s name and public key that is encrypted and certified by third party

• Certifying authority– VeriSign or Equifax

50

Using a Digital Certificate

Disney’s New ‘MyMagic’ Wristbands to Turn Big Data Into Big Profits

http://skift.com/2013/10/06/disneys-new-mymagic-wristbands-to-turn-big-data-into-big-profits/#4

51

52

53

Final Exam

• Chapters 1 to 12 and 14 and 15(5th Edition)

• 20 multiple choices

• 3 short questions

• OO diagram– Use Case– Class– Sequence