Page 150 - DCAP405_SOFTWARE_ENGINEERING

Unit 9: System Engineering

Self Assessment Notes

Fill in the blanks:
1. ………………….., or more specifically dynamic systems, are one of the most pervasive
notions of our contemporary world.

2. The analysis, design, and ………………… of targeted system element are initiated.
3. A system is understood to be an entity which maintains its existence through the interaction
of its………………...

9.2 Types of Models

System Modelling

System modelling helps the analyst to understand the functionality of the system and models
are used to communicate with customers
Different models present the system from different perspectives

External perspective showing the system’s context or environment
Behavioural perspective showing the behaviour of the system
Structural perspective showing the system or data architecture

Structured Methods

Structured methods incorporate system modelling as an inherent part of the method
Methods define a set of models, a process for deriving these models and rules and guidelines
that should apply to the models
CASE tools support system modelling as part of a structured method

Method Weaknesses

They do not model non-functional system requirements
They do not usually include information about whether a method is appropriate for a given
problem
The may produce too much documentation
The system models are sometimes too detailed and difficult for users to understand

Model Types

Data processing model showing how the data is processed at different stages

Composition model showing how entities are composed of other entities
Architectural model showing principal sub-systems
Classification model showing how entities have common characteristics
Stimulus/response model showing the system’s reaction to events

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