System design, implementation, maintenance and review

1
System design, implementation, maintenance and
review

• Logical and physical approaches

2
What do information systems consist of?

• Logical aspects of systems
• Inputs and outputs
• Processes
• Files/databases
• Telecomm. networks
• Procedures to follow
• System security
• Personnel to execute tasks (i.e. what they do?)

• Physical aspects of systems
• Hardware and software
• Files/databases
• Telecomm. Networks
• Personnel (who they are?)
• Enforcement of security controls

3
Systems analysis and design tools

• Logical tools
• Hierarchy charts
• HIPO charts
• DFDs
• ERDs
• WODs
• Fishbone diagrams using Visio
• Dialogue layout

• Physical tools
• Program flow-charts
• System flow charts
• I/O layout forms
• DFDs

4
Some I/O design tools

• Input/Output design forms and guidelines
• Dialog design forms and guidelines

5
Design for security and preventing errors

• Security design - Inadvertent errors
• h/w failures
• s/w failures
• data errors (audit trails and check digits)
• Remedies for inadvertent errors
• periodic backups
• stored replacement parts for h/w
• off-site processing contracts
• priority service contracts
• data entry verification and correction procedures
• disaster recovery procedures

6
Installation/conversion/cutover pros and cons and
where they are used

• Crash approach (direct conversion)
• Phased approach
• Parallel approach
• Pilot approach (migration)

7
Post Implementation Review.

• When?
• Why?
• Managerial/supervisory commitment?

8
The review team members.

• neutral leader
• system person
• user representative
• managers?

9
End system design
10
Designing hardcopy and on-line reports

• identify targets of reports
• layout of reports
• title
• column headers and footers
• column and row design (size, format)
• tools for laying out forms
• left justified
• butterfly

11
Designing input forms

• Title on top
• Purpose must be clarified
• Logical flow
• Do not interrupt logic
• Ask for relevant data only
• Must be easy to code to reduce coding errors
• Identify alternative input methods to reduce
  coding errors

12
Designing dialogues

• identify users of dialogue
• select type of dialogue to fit situation
• menu selection
• question/answer
• form fill
• sketch flow of dialogue
• specify needed response times e.g.
• display rate
• user think time
• user response time
• apply a user point of view
• software tools (see Access!)
• input charts

13
Dialogue design dos and donts

• use simple, grammatically correct sentences.
• dont be funny or cute
• dont be condescending (dont offer rewards or
  punishments)
• avoid computer jargon and most abbreviations
• be consistent in the use of terminology
• convert instructions into action verbs
• use words such as PRESS (not HIT or DEPRESS)
• also, we should say POSITION THE CURSOR (not
  POINT)
• follow a logical flow

14
Programming symbols and the three basic
programming structures in the process of
structured programming.