Requirements modeling
It’s important to revisit the model concept before we proceed
What's modeling as applied to system?
It’s a graphical representation of a concept or process that systems
developers can analyze, test, and modify
Systems analysts usually describe an information system by using a set of
business data, object, network and process models.
A business model will describe information that a system must provide and
may consist of diagrams, charts, and documentation
Requirements modelling is a fact-finding process aimed at describing the
current system and identification of the requirements for the new system.
A system requirement is a characteristic or feature that must be included
in an information system to satisfy business needs and should be
acceptable to users.
System requirements serve as a benchmark to measure the overall
acceptability of the system. Hence the need to properly document the
system requirements
System requirements are classified into five categories namely:
• Outputs
• Inputs
• Processes
• Performance
• Security & control.
Hence a requirements model will include all the five elements
Input:
Output:
system inputs represent data that enter the system. It could be
manual or automatic
System outputs represent information produced by the system.
It may be electronic or printed
Process:
System processes are logical rules applied to transform data
into meaningful information.
Performance:
Performance refers to the following system
characteristics;
Speed, volume, capacity, availability, and reliability
Security& control:Security and control requirements looks at hardware,
software, and controls that safeguard and protect the
system and its data from threats both external and
internal.