What is Software Requirements Specification(SRS) document? A Software Requirements Specification(SRS) document is a document that describes the requirements of a software system. In other words, it’s a document that lays out all the necessary information for a software project to be delivered. The SRS documents also tend to respond best to changes in requirements once the project progresses.

What does an SRS consist of

The text structure of an SRS consists of models and diagrams, code sample modules, flowcharts, and tables with data collected from usability studies or interviews with key stakeholders. The structure also includes instructions on prioritizing the various elements from highest priority to lowest priority as well as for instructions on how to make decisions when needed or handling choices where possible.

The text structure also consists of different types of requirements. The requirements can be classified into two types.

Types of Requirements

a) Functional requirements

Functional requirements are the capabilities needed to provide the functional services in the software product. Functional requirements describe what the system must do, but not how it will be done. Functional requirements are also known as “use cases” in UML diagrams or “requirements for use.”

b) Non-functional requirements

Requirements describing how a system functions are called non-functional requirements. Non-functional requirements are design qualities that the software should have, such as performance, security, reliability, usability, etc. Non-functional requirements are also known as “requirements for non-functioning” in UML diagrams.

In an SRS, all functional and non-functional requirements should be identified and prioritised at the same time. The sequence of prioritising the functional and non-functional requirements depends on the software development process and each project will have its own sequence. The sequence of prioritising functional and non-functional requirements may be different for each software product.

The elements in an SRS are identified in the analysis phase of the software development life cycle. However, it is not uncommon to have some people stating that there are no elements identified in analysis because the analysis is not about creating the SRS document itself but about creating a preliminary list of functional requirements that can be used in creating an SRS document.

The analysis phase involves identifying business requirements, user requirements, system requirements, technical requirements, quality assurance requirements, etc. The analysis phase involves a lot of different activities and it is a matter of experience to know what should be put in the SRS document and what will not.

There are also some people stating that there are no formal requirements documented because formalized requirements have been replaced by less formalized documents such as use cases, decision tables, etc., but this is not the case.

How is an Software Requirements Specification(SRS) document created

An SRS document can be created using different methods. The method used depends mainly on the type of software product and the person who is responsible for creating it.

An SRS document can be classified into two types: internal and external.

a) Internal SRS

An internal SRS document is the one that developers use while developing a software product and an external one has to be created for customers or users of a software product. Elements that an internal SRS document contains are requirements, specifications, models, user manuals, etc.

b) External SRS

An external SRS document is the one that customers or users of a software product used to understand what a software product can offer or what a software product does. Elements that an external SRS document contains are documents describing the design, user manuals, screenshots of user interface, etc. An SRS document has to be created for an external user and it is not created for developers working on the project.

In the case of a business information system, the SRS document should be created in a way that it can also be used for other users or customers. This means that the SRS document has to be created in a way that it can be used by different types of users. For example, an SRS document of an airline ticket system has to be written in a way that it can also be used by frequent flyers and also by employees working at airliners.

Who is responsible for creating an Software Requirements Specification(SRS) document?

An SRS document is usually created by the software developers working on the project because they are the ones who know which requirements need to be implemented and included in the software product. However, this doesn’t mean that it is the only person who creates an SRS document. There are other people who can create the SRS documents and they include: Project managers, software stakeholders and other engineers.

How can an SRS document be used

The output of an SRS can be used by the software designers working on the project to create a design for the software product. The design can be used later by the software developers to create a software product. Then, the design will be modified and implemented in the software product.

Before creating an SRS document, it is important for all project stakeholders to agree on which type of system they will be developing and what capabilities they need. This means that all stakeholders should define what functional and non-functional requirements they need or how a certain function should work in their system.

All SRS documents can be a little different depending on the software system being built and the target business environment it’s going to be used in.

How is an SRS document important?

There are different ways to present information in an SRS document. The important thing is to provide a high level of information so that all project stakeholders can understand what has to be built and how it will work.

A good way of presenting an SRS document is using UML diagrams, flowcharts, tables, etc.

It is important for developers to understand what they are going to develop so that they can successfully develop the desired software product. They need to know who the system will be developed for, what the system will offer, how it will look like so that they can create a design.

As discussed before, the SRS document is also important for customers or users of a software product because they need to know what kind of functionality they can expect from using the software product. It is also important that customers or users are aware of which features are included in the software product and that there are no hidden surprises when using it.

An SRS document can be used later by developers as an input for creating test cases and test scripts.

Conclusion

SRS documents are very important because they are one of the software documentation tools that can be used to help teams develop software products. The key objective of an SRS document is to have a clear understanding by all project stakeholders on how the software product will be built and to have a high level of information about what is included in the software product.

The output of an SRS document is very important for all types of stakeholders because it provides them with information about what will be implemented in the software product, what functional requirements are being implemented, which non-functional requirements are being implemented, etc.

Read on why test documentation is important here.