A software requirements specification (SRS) is a description of a software system to be developed. It lays out functional and non-functional requirements, and may include a set of use cases that describe user interactions that the software must provide.
Contents
Software requirements specification establishes the basis for an agreement between customers and contractors or suppliers (in market-driven projects, these roles may be played by the marketing and development divisions) on what the software product is to do as well as what it is not expected to do. Software requirements specification permits a rigorous assessment of requirements before design can begin and reduces later redesign. It should also provide a realistic basis for estimating product costs, risks, and schedules. Used appropriately, software requirements specifications can help prevent software project failure.
The software requirements specification document enlists enough and necessary requirements that are required for the project development. To derive the requirements we need to have clear and thorough understanding of the products to be developed or being developed. This is achieved and refined with detailed and continuous communications with the project team and customer till the completion of the software.
The SRS may be one of a contract deliverable Data Item Descriptions or have other forms of organizationally-mandated content.
Structure
An example organization of an SRS is as follows:
Goals
The Software Requirements Specification (SRS) is a communication tool between stakeholders and software designers. The specific goals of the SRS are:
Reliability Availability Security Maintainability Portability.
Requirements Smells
Following the idea of Code smells, the notion of requirements smells has been proposed to describe issues in requirements specification where the requirement is not necessarily wrong but could be problematic. In particular, the requirements smell :
Examples of requirements smells are Subjective Language, Ambiguous Adverbs and Adjectives, Superlatives and Negative Statements. Several of these smells can also be automatically detected with tools like Requirements Scout.