MIS 161 Systems Development Life Cycle II Lecture 3: Remember Prototyping? Data Storage Interface Design

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MIS 161Systems Development Life Cycle
IILecture 3Remember Prototyping?Data
Storage Interface Design
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Prototyping
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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.

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How is it Used?

• As a methodology
• As a technique/tool within the SDLC.
• Some phases supported/replaced

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Approaches

• Type I - Iterative
• becomes final system
• Type II - Throwaway
• used as model for final system

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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
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Type II (Throwaway) Life Cycle
Requirements Definition
Analysis
Design Prototype
Code Prototype
Test Prototype
No
Acceptable?
Yes
Code Final System
No
Test Final System
Implement Final System
Maintain Final System
Yes
Acceptable?
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Types of Prototypes

• Illustrative
• Mock-ups
• Simulated
• Looks like they work, but are simulations
• Functional
• Does some processing, but doesnt store data
• Evolutionary
• Used to produce an operational systems

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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

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Levels (Continued)

• Level 3 (Adaptive)
• working model of system
• system with training wheels
• no bells or whistles

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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

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Disadvantages

• Poor documentation
• Hard to control/manage
• (Unrealistic) User expectations
• time for final system
• final system differences
• reduced analysis

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Data Storage
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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

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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

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Dimensions of Data Storage Optimization

• Storage efficiency (minimizing storage space)
• Speed of access (minimizing time to retrieve
  desired information)

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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

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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

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Types of Databases

• Relational
• Object-relational
• Object-oriented

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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

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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

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Interface Design Specifications
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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.

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Window Navigation Diagram (WND)

• Models changes of the state interface
• Each state represented as a box
• Transitions

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Designing the User Interface
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The User Interface

• The user interface is the system which helps
  users' communication with the computer system
  and/or the application system

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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

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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

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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

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Input Design Objectives

• The quality of system input determines the
  quality of system output
• Well-designed input objectives
• Effectiveness
• Accuracy
• Ease of use
• Consistency
• Simplicity
• Attractiveness

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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

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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

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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

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Minimal User Action

• Minimal user action is achieved by
• 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

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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

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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

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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

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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

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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

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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

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Types of Feedback

• Feedback to the user is necessary in seven
  distinct situations
• 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

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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