Download Data Storage Interface Design

MIS 161
Systems Development Life Cycle II
Lecture 3:
Remember Prototyping?
Data Storage
Interface Design
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Prototyping
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Definition
• A PROTOTYPE is a model of the system
– It can be as simple as mock-ups of reports or
screens, or as complete as software that actually
does some processing.
– Can be used as a communication tool between
analyst and user.
• Prototyping is the process of developing
prototypes.
• Prototyping strategy indicates the type of
prototype used.
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
How is it Used?
• As a methodology
• As a technique/tool within the SDLC.
– Some phases supported/replaced
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Approaches
• Type I - Iterative
– becomes final system
• Type II - Throwaway
– used as model for final system
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Type I (Iterative) Life Cycle
Requirements
Definition
Prototype
Training
Project
Planning
Rapid
Analysis
Database
Design
Design
Prototype
Generate
Prototype
Test
Prototype
No
Acceptable?
Yes
Implement
System
Maintain
System
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Type II (Throwaway) Life Cycle
Requirements
Definition
Analysis
Design
Prototype
Code
Prototype
Test
Prototype
Acceptable?
No
Yes
Code Final
System
Test Final
System
Sylnovie Merchant, Ph.D.
No
Acceptable?
MIS 161
Yes
Implement Final
System
Maintain Final
System
Spring 2005
Types of Prototypes
• Illustrative
– Mock-ups
• Simulated
– Looks like they work, but are simulations
• Functional
– Does some processing, but doesn’t store data
• Evolutionary
– Used to produce an operational systems
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Evolutionary Prototype Levels
• Level 1 (Input-Output)
– printed reports and on-line screens
– screen flow sequence
– screen options
• Level 2 (Heuristic-Learning)
– updating database
– basic transactions
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Levels (Continued)
• Level 3 (Adaptive)
– working model of system
– system with training wheels
– no bells or whistles
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Advantages
•
•
•
•
Speed
Easier for end-users to learn
System changes discovered earlier
End-user involvement (ownership)
– increased user satisfaction
– increased user acceptance
• User-analyst communication
• Early problem detection
– reduced development time
– reduced maintenance
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Disadvantages
• Poor documentation
• Hard to control/manage
• (Unrealistic) User expectations
– time for final system
– final system differences
– reduced analysis
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Data Storage
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Data Storage Design Objectives
• The objectives in the design of data storage
organization are
– The data must be available when the user wants to
use it
– The data must have integrity
• It must be accurate and consistent
– Efficient storage of data as well as efficient
updating and retrieval
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Data Storage Design Objectives
• Further design objectives
– The information retrieval be purposeful
– The information obtained from the stored data
must be in an integrated form to be useful for
•
•
•
•
Managing
Planning
Controlling
Decision making
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Dimensions of Data Storage Optimization
• Storage efficiency (minimizing storage space)
• Speed of access (minimizing time to retrieve
desired information)
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Approaches to Data Storage
• There are two approaches to the storage of data
in a computer system
– Store the data in individual files each unique to a
particular application
– Storage of data in a computer-based system
involves building a database
• A formally defined and centrally controlled store of data
intended for use in many different applications
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Files
• A file contains groups of records used to provide
information for operations, planning, management,
and decision making
• Files can be used for storing data for an indefinite
period of time, or they can be used to store data
temporarily for a specific purpose
• A file can be designed and built quite rapidly, and the
concerns for data availability and security are
minimized
• Analysts can choose an appropriate file structure
according to the required processing speed of the
particular application system
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Types of Databases
• Relational
• Object-relational
• Object-oriented
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Objectives of Effective Databases
• The effectiveness objectives of the database
include
– Ensuring that data can be shared among users for a
variety of applications
– Maintaining data that are both accurate and
consistent
– Ensuring all data required for current and future
applications will be readily available
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Objectives of Effective Databases
• Further effectiveness objectives of the
database include
– Allowing the database to evolve and the needs of
the users to grow
– Allowing users to construct their personal view of
the data without concern for the way the data are
physically stored
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Interface Design Specifications
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Interface Structure Design
• Basic components of the interface
• How these components work together
• Windows Navigation Diagram (WND)
– Depicts how the users of an application
may go from window to window through
menus/command buttons.
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Window Navigation Diagram (WND)
• Models changes of the state interface
– Each state represented as a box
– Transitions
Return required
Return not required
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Designing the User Interface
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
The User Interface
• The user interface is the system which helps
users' communication with the computer
system and/or the application system
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
User Interface Design Objectives
• To design a better user interface, use the
following objectives:
– Effectiveness as achieved through design of
interfaces that allow the user to access the system
in a way that is congruent with their individual
needs
– Efficiency as demonstrated through interfaces that
increase speed of data entry, and reduce errors
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
User Interface Design Objectives
• Further interface design objectives
– User consideration as demonstrated in designing
suitable interfaces, and providing appropriate
feedback to users from the system
– Generating usable queries
– Productivity as shown through following sound
principles of design for user interfaces and work
spaces
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Online Screen Design
• Guidelines for screen design are
–
–
–
–
Keep the screen simple
Keep the screen presentation consistent
Facilitate user movement among screens
Create an attractive screen
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Input Design Objectives
• The quality of system input determines the
quality of system output
• Well-designed input objectives
–
–
–
–
–
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Effectiveness
Accuracy
Ease of use
Consistency
Simplicity
Attractiveness
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Form Design
• Guidelines for good form design
– Make forms easy to fill out
– Ensure that forms meet the purpose for which they
are designed
– Design forms to assure accurate completion
– Keep forms attractive
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Dialog
• Dialog is the communication between a person
and the computer
• Three key points to be considered
– Meaningful communication
– Minimal user action
– Standard operation and consistency
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Communication
• Communication means that the user
understands the information that is being
presented
• Users with less skill require a greater amount
of communication
• Provide easy to use help screens
• Often these contain hyperlinks to other related
help topics
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Minimal User Action
• Minimal user action is achieved by
–
–
–
–
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Entering codes instead of code meanings
Enter only data that are not stored on files
Not requiring users to enter editing characters
Supplying default values on entry screens
Providing inquiry programs with short entry fields
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Minimal User Action
• Further key points
– Providing keystrokes for selecting menu options
that are normally selected using a mouse
– Selecting codes from a pull-down menu on a GUI
screen
– Provide context-sensitive menus, displayed when
the right mouse button is clicked on an object
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Standard Operation
• Standard operation is achieved by
– Keeping header and footer information in the same
locations for all screens
– Using the same keystrokes to exit a program
– Using the same keystrokes to cancel a transaction
– Using a standard key for obtaining help
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Standard Operation
• Further key points
– Standardized use of icons when using graphical
user interface screens
– Consistent use of terminology within a screen or
Web site
– Providing a consistent way to navigate through the
dialog
– Consistent font alignment, size, and color on a
Web page
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Tab Control Dialogue Boxes
• Tab control dialog boxes are a feature of GUI
design
• They should have logically grouped functions
on each tab
• Each tab dialog box should have OK, Cancel
or Apply, and perhaps Help buttons
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Evaluating User Interfaces
• The five useful standards in evaluating the
interfaces are
– The training period for users should be acceptably
short
– Users early in their training should be able to enter
commands without thinking about them, or
referring to a help menu or manual
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Evaluating User Interfaces
• Continued evaluation guidelines
– The interface should be "seamless" so that errors
are few, and those that do occur are not occurring
because of poor design
– Time necessary for users and the system to bounce
back from errors should be short
– Infrequent users should be able to relearn the
system quickly
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Types of Feedback
• Feedback to the user is necessary in seven
distinct situations:
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–
–
–
–
–
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The computer has accepted the input
The input is in the correct form
The input is not in the correct form
There will be a delay in processing
The request has been completed
The computer cannot complete the request
More detailed feedback is available
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005
Program Help
• Program help comes in a variety of ways:
– Pressing a function key, such as F1
– A GUI pull-down menu
– Context-sensitive help, specific for the operation
being performed
– Iconic help, obtained when a cursor is left over an
icon for a few seconds
Sylnovie Merchant, Ph.D.
MIS 161
Spring 2005