Transcript IT Applications Theory Slideshows

VCE IT Theory Slideshows
Problem Solving Methodology 1
Analysis
By Mark Kelly
McKinnon Secondary College
Vceit.com
Contents
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Activities
Purpose
Scope
Constraints
Software Requirements Specification (SD)
Analysis
• Investigates the problem before
attempting to solve it.
• Observe the existing system
before doing anything else
• Like a doctor examines you before
prescribing pills or surgery
Observing
• Measure the
system’s
performance
• Interview users
• Refer to system logs
(e.g. errors,
complaints, repairs)
• Examine system’s
output
First question to ask
• Is there really a problem?
• Sometimes, there is no problem: that’s the
best the system can do
• E.g. your home wireless network is not
reaching the claimed 54Mbps transfer speed
mentioned on the box
• Not a problem: that’s only a theoretical
maximum which is never likely to be actually
achieved.
Don’t bother
• Can’t solve problems that don’t actually exist
• But you can waste a lot of time and money
trying.
Second question
• Can it be fixed?
• Technical feasibility
• Some problems
cannot be fixed, e.g.
a horse’s broken leg.
• Pointless to even try.
• Don’t waste time and
money on a hopeless
cause.
Third question
• Is it worth fixing?
• Economic feasibility
• Some problems are not worth the necessary
time, money and effort
• You can maybe get a
pushbike to do 150km/h
but surely it’s easier to get
a motorbike instead?
And more questions
• Legal feasibility – can you fix it without
breaking any laws?
• Operational feasibility – if you fix it, do you
have the staffing, equipment, skill base,
money etc to continue to operate it?
Scope of the solution
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What can the solution do?
What can't the solution do?
The boundaries or parameters of the solution.
How will the solution benefit the user?
Constraints
• What conditions need to be considered when
designing a solution? E.g.
– cost,
– speed of processing,
– requirements of users,
– legal requirements,
– security,
– compatibility,
– level of expertise,
– capacity,
– availability of equipment
If the answers are not all “YES”
• GIVE UP
• Cancel the project
• Better to give up now than to proceed and
waste far more time and money on a doomed
project.
Determine solution requirements
• What information does the solution have to
provide?
• What data is needed to produce the
information?
• What functions does the solution have to
provide?
Solution Requirements
• Put into a logical design.
• Lays down the specifications of the new or
modified system.
• Specifies what it should be able to achieve.
Logical Design
• Like a “wish list” of features
• Only lists specifications, e.g. “should be able
to produce 20,000 invoices in 2 hours with
99.9% accuracy”
But
• The logical design does not attempt to say
how these objectives will be achieved.
• Don’t jump to conclusions about what
software, hardware etc will be needed.
• Just define what you want it to do.
These requirements can be
• Functional - what the solution is required to do
• Non-functional, which attributes the solution
should possess, such as
– user-friendliness,
– reliability,
– portability,
– robustness,
– maintainability.
Tools
Logical design tools to assist in determining the
solution requirements include ...
• context diagrams,
• data flow diagrams and
• use case diagrams
• Logical Data Dictionaries (e.g. “What data
should be in a sales contract?
• Hierarchy Charts / Organisational chart
• Decision Trees
If all the answers are “YES”...
• All data collected during analysis needs to be
documented for later reference.
• Each step in the PSM must be fully and
properly finished before the next step begins
Finally
• The client, or boss, gives approval to move
onto the next step: design
VCE IT THEORY SLIDESHOWS
By Mark Kelly
McKinnon Secondary College
vceit.com
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