Software requirements specification (SRS):

What is a SRS ?

  • SRS is the official statement  of what the system developers should implement.
  • SRS is a complete description of the behavior of the system to be developed.
  • SRS should include both a definition of user requirements and a specification of the system requirements.
  • The SRS fully describes what the software will do and how it will be expected to perform.

What is the purpose of SRS ?

  • The SRS precisely defines the software product that will be built.
  • SRS used to know all the requirements for the software development and thus that will help in designing the software.
  • It provides feedback to the customer.

Who are the users of a SRS ?

(End Users) Customers : Specify the requirements and and check them they meet their needs. Customers specify changes to the requirements.

Managers : Use the requirements to plan the development process.

System engineers : Use the requirements to understand what system is to be developed.

System test engineers : use the requirements to develop validation test.

System maintenance engineers : use the requirements to understand system and establish relationship between them,

Structure of the SRS ?

According to IEEE standard the structure of SRS is as following :

1. Introduction
   1.1. Purpose
   1.2. Scope    
   1.3. Definitions, acronyms & abbreviations
   1.4. References
   1.5. Overview
2. Overall description
   2.1. Product perspective
        2.1.1. System interfaces
        2.1.2. User interfaces
        2.1.3. Hardware interfaces
        2.1.4. Software interfaces
        2.1.5. Communications interfaces
        2.1.6. Memory constraints
        2.1.7. Operations
        2.1.8. Site adaptation requirements
   2.2. Product functions
   2.3. User characteristics
   2.4. Constraints
   2.5. Assumptions and dependencies
   2.6. Apportioning of requirements
3. Specific Requirements

3.1 External interface requirements
3.1.1 User interfaces
3.1.2 Hardware interfaces  
3.1.3 Software interfaces   
3.1.4 Communication interfaces  
3.2 Specific requirements
3.2.1 Sequence diagrams
3.2.2 Classes for classification of specific requirements
3.3 Performance requirements
3.4 Design constraints
3.5 Software system attributes
3.5.1 Reliability
3.5.2 Availability
3.5.3 Security
3.5.4 Maintainability
3.6 Other requirements
4. Supporting information
4.1 Table of contents and index
4.2 Appendixes

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