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Usability Engineering Lifecycles. As Part of User-Centred Design. What This Lecture Is About. The problem with software today Usability engineering lifecycles Next: early analysis activities. Building a UI — What Do We Know?. Principles of UI development are neither obvious nor intuitive - PowerPoint PPT Presentation
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Usability Engineering Lifecycles
As Part of User-Centred Design
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What This Lecture Is About
1. The problem with software today2. Usability engineering lifecycles Next: early analysis activities
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Building a UI — What Do We Know?
Principles of UI development are neither obvious nor intuitive
Principles of UI development are not applied as often as they should be
Developing a UI is part of the larger problem of developing software
What are the big trends driving the field today? The software crisis Software chronic problem
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Special Challenges to UI Development
The communications explosionThe media explosionThe usability explosion
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The Communications Explosion
Essence of UI used to be one-user, standalone. Now moving more toward connectivity (e.g., WWW, CSCW, etc.)
Superhighway; Communications services; Expanding user pops
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The Media Explosion
Mice, pens, touch screens, video, speech, VR etc.
UI code is half the codeGets more complicated, the more
the media (e.g., multimedia)
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The Usability Explosion
Users want availability (open architecture)
Increased awareness of costs of poor UIs
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The SE S/W Dev. Life Cycle Plus UE
Waterfall model Systematic, sequential approach to
software development Begins at system level and progresses
through a series of phases
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Waterfall Model (picture)
System Engineering
RequirementsAnalysis
Design
Coding
Testing
Maintenance
Classic Lifecycle Model
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Phases
Systems engineering and analysisSoftware requirements analysisSoftware designCodingTesting Maintenance
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Integrating UE Processes
Curtis & Hefley
Figure 5 (p. 31)
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Issues for Waterfall Model
The waterfall model is the oldest and most widely-used paradigm for software engineering
Following any methodology imposes discipline on the software development process
It appears to be easy to specify a timetable and costing for s/w developed with the waterfall model
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Some Problems (1)
Real problems rarely follow the sequential flow that model suggests: Iteration always occurs and Creates problems in the application of the
paradigm
Difficult for customer to state all requirements explicitly: Life cycle has difficulty accommodating
uncertainty that exist at beginning of many projects
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Some Problems (2)
Customer must have patienceWorking version of the software will
not be available until late in the time span
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Spiral Model
Common model for risky development
Iteration is built-inIt is ‘rapid’ but still rigid
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Spiral Model
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The ‘Let's Get Real’ Model
Hix & Hartson observed that UI developers worked in ‘alternating waves’ of top-down, bottom-up, inside-out, …See Star Life Cycle figure
Fig. 4.2 in Hix & HartsonFigs 6.13 in Preece et al. (2002)Figs. 2.8, 18.5 in Preece et al. (1994)
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Star Life Cycle
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The Star Life Cycle Is…
Not sequential Activities can proceed in any order
Evaluation-centred Each activity is evaluated
Interconnected Through the evaluation in the middle
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Getting Started—specifics
SE/UI lifecycle divided into Definitional activities
(Called ‘early system analysis activities’)
Development/design activities
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Early System Analysis Activities
Documents concerned with Detailing the UI from the user’s
perspectiveGoal
Produce detailed documents that spell out as specifically as possible what the UI for the product will be like
Details See the ‘early analysis activities’ slides