requirements analysis 8. 1 storyboarding - 2005b508.ppt © copyright de montfort university 2000 all...

Requirements Analysis 8. 1 Storyboarding - 2005b508.ppt

© Copyright De Montfort University 2000All Rights Reserved

INFO2005Requirements Analysis

Human Computer Interaction

Department of Information Systems



Learning Objectives

Define HCI Explain why we consider HCI within

Requirements Analysis Introduce the main metaphors

used in HCI design Overview major approaches to HCI

design



What is HCI? A sub-discipline of Information

Systems Focuses on interaction between a

computer system and its users Has also become popular short-hand

for:

People often say “good HCI” when they really mean “good HCI design”



What is HCI?

HCI draws on:



Where Does HIC Fit in the System Architecture?

HCI is implemented in the presentation layer of an application:

Campaign Database

Campaign Domain

Advert

Sub-system

Advert HCI

Sub-system

Campaign Costs

Sub-system

Campaign Costs

HCI Sub-system

Application layer

Presentation layer

Domain layer

Database layerAdapted from Bennett et al,

1999



Locating HCI in the traditional Life Cycle

Traditionally seen as part of design phase E.g. Hoffer et al puts HCI in Logical Design:

Analysis

Adapted from Hoffer et al, 1998

Logical Design

Physical Design

Forms and ReportsDialogues and

InterfacesFiles and Databases



Locating HCI in the RUP

In RUP, HCI fits in many places

E.g. in the Requirements Analysis Workflow:



Locating HCI in the RUP

In RUP, UI prototypes are an important tool for:

The UI designer works closely with the Use Case specifier (may be the same person)



Why Consider HCI with Requirements Analysis?

Reasons to include in requirements analysis:– To capture usability requirements, ease of

learning, environmental factors– Importance of interface requirements for

interactive systems– Prototyping presents UI to users much

earlier in life cycle– Even prototypes must be adequately

designed!



Problems with Considering HCI within Requirements Analysis Some important drawbacks must

be kept in mind: Don’t get too attached to

prototypes – not necessarily the final UI

Remember that prototype design features (e.g. data content and structure) analysis features



Two Main Metaphors Understanding of how HCI works best

is based on two main metaphors:

Dialogue

Direct Manipulation

In practice, often use both together



The Dialogue Metaphor

A dialogue may be a natural translation of a Use Case scenario:

User selects option from menuSystem displays order entry form (date and next order no filled in automatically)User enters Customer CodeSystem displays name and address of customer (to confirm correct number entered)Etc...



Types of Message in a Dialogue

Input control User directs way in which dialogue will proceed

data Numbers, codes and quantities supplied by user

Output prompt Request for user input

data Data from application following user request or input

status Acknowledgement that something has happened

error Processing cannot continue

help Additional information to user

Adapted from Bennett et al, 1999



Direct Manipulation Metaphor Creates impression that user

physically handles objects on screen Reflected in windowing systems jargon You can:



Direct Manipulation

Owes much to spread of event-driven programming

Graphical objects displayed on screen System responds to events Most events are result of user actions UI design more complicated than for

straightforward dialogue style (because interaction sequence is less

predictable)



Principles of Good Dialogue Whatever the underlying

metaphor, good UI design includes:

Style guides (e.g. from Microsoft) show how best to implement these principles



Approaches to UI Design

Three main categories of approach to UI design:

All three cover requirements gathering, UI design and UI evaluation



Structured Approaches

Assume a structured approach to systems development as a whole

UI design and development runs alongside main project lifecycle

Generally provide detailed specification of tasks and steps in UI development

Examples: STUDIO and RESPECT



Example Structured Approach This diagram

shows an overview of the STUDIO approach

301 Task

Synthesis

302 Style Guide

STAGE 2

303 Design

Specification

301 Task

Synthesis

304 User

Support

User Support Documentation

Task Hierarchy Diagrams

Task Hierarchy Diagrams Knowledge Representation

Grammars Action List Object List

Interaction Rules

User Interface Style

General User Interface

Decisions

Textual Content of Dialogue

User Interface Specification User Interface Function

Catalogue

STAGE 4

Bennett et al, 1999, adapted from Browne, 1994



Ethnographic Approaches

“Ethnography” applies to a range of techniques in sociology / anthropology

A particular philosophy about scientific enquiry

Only by being part of a situation can you truly understand and interpret it

In HCI this means spending time with users immersed in everyday working life



Ethnographic Approaches

Users interpret systems subjectively HCI professional must understand

this, not assume they can assess objectively

Only thus can real requirements be understood and documented

Xerox PARC has employed trained ethnographers for many years



Scenario-Based Approaches Scenario-based approach fits

naturally with Use Case driven development– Less formal than structured approaches– More organised than ethnographic

approaches– Similar to Use Case descriptions– Can show alternative realisations of a use

case– Can also include “claims” – justification of

design decisions



Scenario-Based Approaches Potential disadvantage: a large

amount of textual documentation can be generated

Requires careful management and cross-referencing



Summary

Defined HCI Explained why we consider HCI

within Requirements Analysis Introduced the main metaphors

used in UI design Overviewed 3 main types of

approach to UI design



References

Bennett, S., McRobb, S. & Farmer, R. (2002) “Object-Oriented Systems Analysis and Design using UML”, McGraw-Hill, Maidenhead. (Ch 14 & 16)

Jacobson, I., Booch, G. and Rumbaugh, J. (1999), The Unified Software Development Process, Addison Wesley, Reading Mass. (Ch 7)

Hoffer, J. A., George, J. F. and Valaich, J. S. (1998), Modern Systems Analysis & Design, Addison Wesley Longman, Reading Mass. (Ch 15)

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