Page 152 - DCAP305_PRINCIPLES_OF_SOFTWARE_ENGINEERING

Principles of Software Engineering

Notes • A top-down approach (is also known as step-wise design) is essentially the breaking down
of a system to gain insight into its compositional sub-systems.

• A bottom-up approach is the piecing together of systems to give rise to grander systems,
thus making the original systems sub-systems of the emergent system.

• The software quality metrics of coupling and cohesion were invented by Larry Constantine,
an original developer of Structured Design.

• Functional modelling is a system engineering technique that requires the graphical design
and presentation of complex business models.

• A DFD shows the flow of data through a system. It views a system as a function that
transforms the inputs into desired outputs.
• Heuristic evaluation requires only one expert, reducing the complexity and expended
time for evaluation.

6.13 Keywords

Domain: A domain name is an identification string that defines a realm of administrative
autonomy, authority, or control on the Internet. Domain names are formed by the rules and
procedures of the Domain Name System (DNS).

Flag: Any variable or constant that holds data can be used as a flag. You can think of the storage
location as a flag pole. The value stored within the variable conveys some meaning and you
can think of it as being the flag.

Modular: The basic idea underlying modular design is to organize a complex system (such as a
large program, an electronic circuit, or a mechanical device) as a set of distinct components that
can be developed independently and then plugged together. Preservation measures in relation
to software, both at the development stage and
Preserved: Part of this involved examining the purpose and benefits of employing. Retrospectively
to legacy software.

Thread: The Thread Disk for Windows engineering software calculates critical dimensions for
threads based on ANSI tables and formulas.

Use-case: A use case in software engineering is a description of a system’s behaviour as it
responds to a request that originates from outside of that system.
Draw the flow chart of top-down and bottom-up approach.
Draw the structure of data flow diagrams.

6.14 Review Questions

1. Define functional design and explain the principles of functional design.
1. What is the difference between top-down and bottom-up approach?

2. Write short notes on
(i) Cohesion (ii) Heuristics
3. Write a short note on structure chart.

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