Designing Interfaces and Dialogues
Designing Interfaces and
Dialogues
IMS1002 /CSE1205
Systems Analysis and Design
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Lecture 8.4
Designing Interfaces and Dialogues
At the end of this lecture students should
have some understanding of:
• what are interfaces and dialogues
• how we specify interface and form design
• the different types of interaction -command language,
menu, form and icon-based
• issues concerning data entry
• ways of controlling user access
• the use of graphical user interfaces (GUI)
Copyright 2000 Monash University
Monash University,SIMS, Copyright 2002
Designing Interfaces and
Dialogues
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The process of defining the manner in which
humans and computers exchange information
Analogous to a conversation between 2 people
Interface and dialogue design is critical for
successful information systems
“...to the user the interface is the system”
Should provide a uniform structure for finding,
viewing, and invoking different components of
an information system
Designing Interfaces and
Dialogues
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• Narrative overview
• Interface/dialogue design
• Testing and usability information
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Design Specifications
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Interaction Methods and Devices
Narrative overview
• interface name, user, task, system, environment
Use prototyping as with forms and
reports
Design specifications - also as with
forms and reports
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Common interface methods are:
Interface/dialogue design
• Command language interaction
• form/report designs, dialogue sequence diagram
• Menu interaction
Testing and usability assessment
• testing objectives, procedures and results
• time to learn, speed of performance, rate of errors,
retention over time, user satisfaction and other
perceptions
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• Form interaction
• Icon/object-based interaction
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Designing Interfaces and Dialogues
Command Language Interaction
Menu Interaction
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Users enter explicit commands to invoke
operations
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• users must therefore remember syntax and semantics
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MSDOS, UNIX commands
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• copy A:myfile.doc to B:myfile.doc
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Users select from a list of system options and a
specific operation is executed
Menu interaction is still the most widely used
interaction method
Menus can differ greatly in their design and
capability
Complex applications such as word processors
and spreadsheets may have many commands
• <CTRL-P>
print
• <CTRL-S>
• <CTRL-C>
save
copy
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simple single menu
hierarchy of menus
pop-up menus
drop-down menus
graphic menus
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Monash University,SIMS, Copyright 2002
Simple Single Menu
Menu Hierarchy
Main
Menu
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TEXT-BASED SYSTEM
MENU OF CHOICES
---------------------------BOOKINGS
CUSTOMERS
TOURS
MAINTENANCE
LOGOUT
What’s wrong with this one?
Monash University,SIMS, Copyright 2002
Monash University,SIMS, Copyright 2002
Guidelines for Menu Design
Drop-Down Menu
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Wording
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Organisation
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Length
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Selection
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Highlighting
• meaningful title, clear, unambiguous command verbs
• consistent, eg. related options should be grouped together
• use sub-menus to break up very long menus
• methods should be clear and consistent
• should be minimised and used to convey selected options
(marked) or unavailable options (dimmed)
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Monash University,SIMS, Copyright 2002
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Designing Interfaces and Dialogues
Form Interaction
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Users fill in ‘blanks’ on a form when they
interact with the system
Screen format is similar to paper-based forms
Effective for both input and presentation of
data
Form interaction is common on many
applications, the World Wide Web
Form -based programming languages
• VB, Delphi, CGI(?)
Icon/Object-Based Interaction
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Often based on metaphor
Icons are graphic symbols that look like the
processing option they represent
Operations are selected by pointing at and
clicking on the desired option
Easily understood and take up little
screen space
Many icons appear in the form of buttons
or controls
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Monash University,SIMS, Copyright 2002
Common Interaction Devices
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Keyboard
Mouse
Joystick
Trackball
Touch screen
Light pen
Graphics tablet
Voice
Structuring Data Entry
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Entry
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Defaults
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Units
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Captioning
• never require data to be inserted that is already known
• always provide defaults where appropriate
• make clear units of measure
• always provide a caption near fields to explain meaning
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Monash University,SIMS, Copyright 2002
Structuring Data Entry
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Format
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• provide format details (decinal points, dollar signs, dates
...)
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Justify
Tests are usually handled by DBMS or by
programs:
• Type
• proper type of data (eg. numeric, alpha …)
• automatically justify data entries - numbers right justified;
text left justified
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Validation of Input data
Help
• always provide context sensitive help (use F1)
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• Combinations
• do values in several fields combine in a sensible way
• Missing data
• eg. must have quantity for each customer order
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Designing Interfaces and Dialogues
Validation of Input data
Other Interface Design Features
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Provide feedback
These tests are usually handled either by a
DBMS or by programs:
• give status information to keep users informed
• Range
• give prompting cues
• eg. Please wait while …
• are data within proper range of values?
• eg. Enter customer account no.
• Size
• give meaningful error and warning messages
• correct number of characters?
• Values
• does value come from a standard set of values?
• avoid jargon, be specific
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Provide help
• for help, concepts, procedures, messages,
menus, function keys, commands, etc.
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Monash University,SIMS, Copyright 2002
Controlling User Access
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Mechanisms to control user access include
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• views
• particular users see subset of DB in the interface
• authorisation rules
• restrictions to access and actions on data
• encryption procedures
• encryption and decoding procedures are necessary
for highly sensitive data
• authentication schemes
• access restrictions controlled by passwords, biometric
devices and smart cards
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Graphical User Interfaces
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Are becoming increasingly powerful
Are becoming something of a standard
All previous design guidelines apply,
together with several additional ones
• organisational requirements, contextual issues
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Designing Dialogues
Typical GUI environments include Macintosh
and Microsoft Windows - these come with
extensive guidelines and consistency
standards
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3 major steps:
• 1 Designing the dialogue sequence
• based on how the user wishes to use the system
• 2 Build a prototype
• use tools such as CASE tools, Visual Basic, Access
• 3 Assess Usability
• use same approach as with forms and reports - time to
learn,speed of performance, rate of errors, retention
over time, subjective satisfaction
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References
Hoffer, J.A., George, J.F. and Valacich, (1999)
2nd edn., Modern Systems Analysis and
Design, Benjamin-Cummings, MA USA.
Chapter 14, 15
Whitten, J.L. & Bentley, L.D. and Dittman, K.C.,
(2001) 5th edn., Systems Analysis and Design
Methods, McGraw-Hill Irwin, Burr Ridge, Illinois
Chapter 13, 14, 15
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