What are types of requirements ?

Question 1

what are types of requirements ?

Answer 1

there are two types:
- user requirements : are expressed as statements in natural language and notations.
it includes: the services of the system and the operational constraints.

• system requirements : a structured descriptions in detail which setting up the system functions and the operational constraints.

Question 2

what is the requirement specification ?

Answer 2

is the process of writing down the specification of the software like services and constraints.
these document may be a base for a contract, so it must be complete.
- for user the document specify the services and the constraints .
for system requirement -document : it is more detail about services and technical information for developers .

Question 3

what are the ways of writing a system requirements specification ?

Answer 3

• Natural languages
  the REQ are written in a numbered sentences, each sentence should explain only one requirement.
• structured natural language
  The requirement are written in natural language using a specific structure or template and every field describe an aspect of the requirement
• design description language
  The language approach is nearly close to programming language but it has an abstract to describe the requirements
• graphical notations
  graphical models with text that describe the functional requirement of the system.
  *Mathematical specifications
  Notations are based on a mathematical concept , No ambiguity and reduces it. Most customers don’t understand it, so this make them refusing the contract.

Question 4

requirements and design are inseparable. Explain.

Answer 4

in principle , requirements are the description of what system should do and the design is how does the system do it.

But in practical, design and requirements are inseparable.

• a system requirements may structure the design.
• systems which are dealing with external systems, affect on the design.
• the use of specific architecture to satisfy non functional requirements may be a domain requirement.