AUInterface & Project Analysis

Professor J. Alberto Espinosa

Business AnalysisITEC-630 Fall 2009

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Objectives Discuss interface analysis Discuss project and cost estimation

issues

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Interface Analysis

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Usability

Derives from the industrial engineering field of “ergonomics” – how to design things so they are easy to use.

It refers to the “quality of a user's experience when interacting with a product or system … and how well users can learn and use a product to achieve their goals and how satisfied they are with that process ... people who use the product can do so quickly and easily to accomplish their tasks” – usability.gov

Other references: http://www.usernomics.com/usability.html

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Interface

“The place at which independent and often unrelated systems meet and act on or communicate with each other” – Webster dictionary

Software

Network

Software

Hardware UserSystem

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User Interface Design

Also referred to as “human computer interaction” (HCI) – is what the usability specialists do to build systems that are easy to use.

HCI also derives from the field of “ergonomics” often referred to these days as “human factors” to include digital and virtual interaction, in addition to physical interaction.

Other references:Cornell Univ: http://ergo.human.cornell.edu/ahtutorials/interface.htmlVirginia Tech: http://www.edtech.vt.edu/edtech/id/interface/Carnegie Mellon: http://www.usernomics.com/user-interface-design.html

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ATM System

Customer

Bank Manager

ATM Service Rep

Customer Accounts System

Withdraws Funds

Makes Deposits

Manages Account

Inquires CustomerActivity

Monitors ATMStatus

Replenishes Cash

Upload CustomerTransaction

Data

Use Case Diagram without Interfaces

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ATM System

Customer

Bank Manager

ATM Service Rep

Customer Accounts System

Withdraws Funds

Makes Deposits

Manages Account

Inquires CustomerActivity

Monitors ATMStatus

Replenishes Cash

Upload CustomerTransaction

Data

WithdrawalInterface

Deposit Interface

AccountManagement

Interface

Customer ActivityInquiry Interface

ATM StatusMonitor Interface

CashReplenishment

Interface

CustomerAccounts System

Interface

Use Case Diagram with InterfacesEx.1: 1 Interface per Actor-UC Interaction

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ATM System

Customer

Bank Manager

ATM Service Rep

Customer Accounts System

Withdraws Funds

Makes Deposits

Manages Account

Inquires CustomerActivity

Monitors ATM Status

Replenishes Cash

Upload CustomerTransaction Data

Customer Interface

Customer Activity Inquiry Interface

ATM Status Monitor Interface

Cash Replenishment

Interface

Customer Accounts System

Interface

Use Case Diagram with InterfacesEx.2: 1 Interface for Customer Actor’s Interaction with all UC’s

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ATM System

Customer

Bank Manager

ATM Service Rep

Customer Accounts System

Withdraws Funds

Makes Deposits

Manages Account

Inquires CustomerActivity

Monitors ATM Status

Replenishes Cash

Upload CustomerTransaction Data

Withdrawal Interface

Deposit Interface

Account Management

Interface

Customer Activity Inquiry Interface

Cash Replenishment

Interface

Customer Accounts System

Interface

ATM Monitoring Interface

Use Case Diagram with InterfacesEx.3: 1 Interface for Monitor ATM Status UC all Actors

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If the actor is a user: The interface specification describes how the

user interacts with the system – i.e., the “user interface” (UI) – the “human-computer interaction” (HCI)

If the actor is an external system: The interface specification describes how the

system interacts with that external system actor – i.e., the “application program interface” (API)

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List of Interfaces

Interface Name Actor

Funds Withdrawal User

Funds Deposit User

Account Management User

Customer Activity Inquiry User

ATM Status Monitor User

Cash Replenishment User

Customer Accounts System System

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Each Interface Has:

A name A set of “operation signatures” (for HCI and

API) indicating:– which data to “get” from the actor with the

operation (i.e., Get UserId, Name, etc.)– Which data to “return” to the actor when the

operation is complete A “storyboard” (for HCI only): visual

illustration of the sequence of screen designs to complete these operations

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Example of Operation Signatures: Funds Withdrawal Interface

Get data from card magnetic tapeGet pass code from customer

Get customer transaction selection(user selects withdrawal)

Get account type for withdrawal Get amount to withdraw Return cash, or Return error message to customer Return thank you message to customer

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A User Interface Can Be For:

Input into the system by the user for data entry or to query information from the system

A display output (on screen or other output device) by the system to the user

A printed output (on a printer or other output device)

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Diagramming the Interface: with “Storyboards”

User interfaces can be diagrammed as “storyboards”

A storyboard is a series of drawings that depict how the system looks at the start of the operation and after each significant change to the look of the interface

Is like a sequence of screenshots that follows the use case execution sequence

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Organization of a Storyboard

Storyboard Sequence

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A Bad Interface Storyboard

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What to Include in an Interface Design Specification:

A list of all the interfaces between actors and use cases

For each interface (any actor – user or external system):– Indicate whether the actor is a user (human actor) or an external

system– Prepare a list of operation signatures detailing all the data that is

passed to/from the system before each operation and the data that is returned from/to the system after each operation

For users (human actors only):– Indicate when/if operations are taking place for data input, display

outputs or printed outputs– Prepare a storyboard for all screen input/output displays and printouts– Design the visual interface for all screen input/output displays and

printouts

For external system actors (only):– Indicate when/if operations are taking place to input or output data

from/to the system

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General Quality Attributes of a User Interface Design

Ease of use Intuitive use and navigation Consistency across screens Simplicity – e.g., no clutter, no information

overload, no busy graphics Exit/cancel options for users Forgiving Businesslike appearance Readable and good color contrast

AUProject Issues

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The System Project and the UP

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The Project Plan

It is based on iterations, per the UP Define the iteration length Develop a domain model early Analyze, design, build, integrate, and test often Estimate how many (fixed-length) iterations

you will need for construction Decide the order in which things will be built

based on Use Case priorities Try to build the core functionality of the product

early (or at least prototype it)

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Estimating Project Effort

Estimate the number of lines of code (LOCs)– Difficult to estimate upfront– Depends on the software language used– Not great for object-oriented systems & CASE tools

Constructive Cost Model (COCOMO)– A popular method– Effort estimation based on LOCs estimated– Same difficulties as with LOCs estimation

Use Case Points (UCP)– Similar to function points, but based on Use Case metrics

Function Points (FP)– Estimating effort based on what the software does, not LOCs– Every software function (e.g., a display, report, a data store)

has a function count– Then adjusted to function points based on complexity factors

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Use Case Points (UCP) (Rational Software – a new way of estimating effort)

Count Actors and multiply by their weight:– 1 for a simple actor (an external system with a well

defined interface)– 2 for an average actor (an external systems with less

defined interface or a person using a simple interface)– 3 for a complex actor (people using a more complex

graphical interface) Count Use Cases and multiply by their weight

– 5 for simple Use Cases (3 transactions or less)– 10 for average Use Cases (4-7 transactions)– 15 for complex (more than 7 transactions)– A transaction is a set of Use Case steps performed

entirely or not at all (i.e., number of paths) Unadjusted Use Case Points (UUCP) Adjust for complexity and environmental factors

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Calculate the Technical Complexity Factor (TCF)

Factor Description WeightRating

0: Irrelevant5: Essential

WeightedRating

T1 Distributed system 2

T2 Response performance objectives 1

T3 End-user efficiency 1

T4 Complex internal processing 1

T5 Code must be reusable 1

T6 Easy to install 0.5

T7 Easy to use 0.5

T8 Portable 2

T9 Easy to change 1

T10 Concurrent 1

T11 Secure 1

T12 Access to 3rd parties 1

T13 User training facilities 1

TFactor = Sum of weighted ratings

TCF = 0.6 + (0.01 * TFactor)

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Calculate the Environmental Factor for the Team (EV)

Factor Description WeightRating0: none

3: average5: expert

WeightedRating

F1 Familiar with Rational UP 1.5

F2 Application experience 0.5

F3 Object-oriented experience 1

F4 Lead analyst capability 0.5

F5 Motivation 1 0: none5: highest

F6 Stable requirements 2 0: unstable5: very stable

F7 Part-time workers -1 0: none5: all

F8 Difficult programming language -1 0: easy5: hardest

EFactor = Sum of Weighted ratings

EV = 1.4 + (-0.03 * EFactor)

Use Case Points (UCP) = UUCP * TCF * EV

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FYI Only: Function Points (FP) The traditional way of estimating effort Count:

– Number of user inputs– Number of user outputs– Number of user inquiries– Number of files– Number of external interfaces

Function Count = weight these counts based on their complexity and add them up

Function Points (FP) = adjust for other complexity factors

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Function Count (FC)

Item Description Count x

Weight

=Weighted

CountSimple Avg Complex

Number of user inputs 3 4 6

Number of user outputs 4 5 7

Number of user inquiries 3 4 6

Number of files 7 10 15

Number of external interfaces 5 7 10

Total Weighted Function Count (FC)

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Complexity Factor (CF) and Function Points (FP)Factor Description

Rating0: Irrelevant5: Essential

F1 Reliability and backup recovery

F2 Data communications

F3 Distributed processing

F4 Performance

F5 Operate on existing system

F6 On-line data entry

F7 Data entry over multiple screens

F8 Master files updated on-line

F9 Complex inputs, outputs, files & inquiries

F10 Complex internal processing

F11 Code needs to be reusable

F12 Need conversion and installation

F13 Multiple installations of the system

T14 Easy to change and use

Complexity Factor (CF) = sum of ratings

Function Points (FP) = FC x (0.65 + 0.01 x CF)

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Estimate Effort and Cost from Experience

Project UCP’s FP’s LOCsEffort

(Person-Days

Cost per Person-

Day

TotalCost

ATM System 60.22 45.22 xx 362 $1,200 $434,400

Loan Processing System 82.34 53.21 xx 443 $1,200 $531,600

Order Processing System 95.20 65.22 xx 563 $1,200 $675,600

Point of Sale System 110.65 78.44 xx 615 $1,200 $738,000

Etc.

……… ….. ….. …. …. ….. ….

New project (est.) 134.30 108.77 xx xx $1,200 xx