A Use-case Diagram


A Use-case Diagram

A Class Diagram


A Class Diagram

Sequence Diagrams


Sequence Diagrams

Non-functional Requirements

Define system properties and constraints Eg: reliability, performance, interface, security, storage requirements.

Process requirements may also be specified mandating a particular CASE system, programming language or development method.

Non-functional requirements may be more critical than functional requirements. If these are not met, the system is useless.

Requirements verifiability

  Requirements should be written so that they can be objectively verified.

  The problem with this requirement is its use of vague terms such as ‘errors should be minimized’

  * Experienced controllers should be able to use all the system functions after a total of two hours training. After this training, the average number of errors made by an experienced user should not exceed two per day

Non-functional Requirements measures


Non-functional Requirements measures

Software Requirements Document - IEEE standard

1.      Introduction

      1.1 Purpose of the requirements document

      1.2 Scope of the product

      1.3  Definitions, acronyms and abbreviations

      1.4 References

      1.5 Overview of the remainder of the document

2. General Description

     2.1  Product perspective

     2.2  Product functions

     2.3  User characteristics

     2.4  General constraints

     2.5  Assumptions and dependencies

  1. Specific requirements

       All functional and non-functional requirements

       System models  (eg. DFD, ERD, Use-Case, Class, Sequence diagrams)

       External Interfaces, Performance, database requirements,  design constraints

       Security, quality characteristics

 4. Appendices