Write down the requirements vs Design

Requirements vs. Design
 

Distinction:

 Design solution: HOW to achieve something

 Requirements: WHAT to achieve

Two cases where a requirements and desigin solutions are mixed up:

 The customer mandates a design solution as a requirement

•  Design solution (HOW): “provide a database for X”
• Requirements (WHAT): “capabilities for navigation and sort for X”

 Otherwise:

•  Restrict design space.
• Risk to miss requirements: ask WHY!

Risk to miss requirements: ask WHY!

A derived requirement which is actually a design solution and no
requirement

 

•  See allocation and flowdown
•  Often alternation of requirements analysis and design
•  One person’s design is the next person’s requirements

what are the software requirement for complex systems?

Requirements for Complex Systems :

A system of any but the smallest size will
be decomposed into a hierarchy of
elements (partitioning):

 This is reflected at the requirement level by:
 

(1) Allocation: assigning requirements to
elements
 

(2) Flowdown: requirements which respond to the
allocated highel level requirements
 

(3) Traceability: keep track of the dependencies

Analysis & Negotiation :

 The analysis has to establish an agreed set of requirements
which are complete, consistent, and unambiguous. Such
a set can be used as the basis for systems development.

 Negotiation:

Stakeholders often disagree over requirements.
Therefore they need to negotiate to try to reach agreement.

What are the software requirement analysis?

Requirement Analysis

Requirement Analysis: the process of analyzing
the customers’ and users’ needs to arrive at a
definition of the requirements

requirements analysis.

(1) The process of studying user needs to arrive at
a definition of system, hardware, or software
requirements.
(2) The process of studying and refining system,
hardware, or software requirements.

what are the software requirement elicitation?

Requirement Elicitation :

 Requirement Elicitation: the process through which the
customer and developer discover, review, articulate, and
understand the users’ needs and constraints on the
software and development activities

Requirements elicitation is about discovering what
requirements a system should be based upon

This doesn’t involve just asking stakeholders what they
Want. It requires a careful analysis of:

•  The organization
•  The application domain
•  Organization processes where the system will be used

 To determine what the stakeholders Need.

Requirement Engineering Elements :

(1) Requirement Elicitation

(2) Requirement Analysis

(3) Requirement Specification

(4) Requirement Validation

(5) Requirement Management

Write down the System vs. Software

System vs. Software

 System Requirement Engineering  is the science
and discipline concerned with analyzing and
documenting system requirements.
origin: user needs

Software Requirement Engineering  is the
science and discipline concerned with analyzing
and documenting software requirements.
origin: system requirements and/or specification
 

BUT: For software-intensive systems software
people should be involved in the elicitation of the
system requirements!

What is software requirement priority? Write a good set requirement

Requirement Priority :

• Characterize the relative importance of a
  requirement
•  Basis for trade studies
•  Unlike the other characteristics the priority
  depends on company needs.

A Good Set of Requirements is …

• Correct
•  Unambiguous
•  Complete
•  Consistent
•  Ranked for importance and/or stability
•  Verifiable

what are the types of software requirement compliance level

Requirement Compliance Level :

 Mandatory: must be implemented

 Guidance: desirable that it be
implemented

Information: non-binding statements
which significantly influence the context,
meaning, and understanding of other
requirements

Write the requirement engineering applications

Requirement Application :

Product parameter: applies to a product or service to be
developed

Qualitative – not directly measurable

 children (derived requirements) refine which provide quantifiable
criteria should be met

Quantitative – measurable

children (derived requirements) can be generated for the purpose of
specifying particular approaches to meet this measurable requirement

Program Parameter: activities associated with enabling the
creation of the product/service

Task: effort to be performed

 Compliance Evaluation: methodology for measuring compliance

Regulatory: administrative elements

What are the types of Software Requirement type?

 Requirement Type 

 Primary requirements: 

Sources:

•  Contract or pre-contract document

• established by management or marketing

Derived requirements:
 

•  Derived form a primary requirement
   
• Derived from a

Describe the requirement characteristics

Requirement Characteristics

i. Type: the source and contractual
applicability

ii. Application: the object of a requirement

iii. Compliance Level: the depth of
compliance mandated for a requirement

iv. Priority: relative importance of a
requirement

What is Requirement Engineering?

 Requirement Engineering :

•  Requirement Engineering (RE) is the science and
  discipline concerned with analyzing and documenting
  requirements.

•  requirement.
  (1) A condition or capability needed by a user to solve a
  problem or achieve an objective.
  (2) A condition or capability that must be met or possessed
  by a system or system component to satisfy a contract,
  standard, specification, or other formally imposed
  documents.
  (3) A documented representation of a condition or capability
  as in (1) or (2).