Software Requirement Specification (SRS) Format

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The Software Requirement Definition (SRS) Format, as the name implies, is a detailed specification and description of software requirements that must be met for a software system to be successfully developed. Depending on the type of demand, these requirements can be functional or non-functional. These requirements are grasped by interacting with the customer.

What is Software Requirement Specification (SRS) Format?

SRS is a formal report that serves as a representation of software, allowing consumers to determine whether it (SRS) meets their needs. It also includes system user needs as well as thorough system requirements specifications.

Properties of Good SRS

qualities of SRS

Since the SRS document is very crucial for software development, it is typically expected to be:

  • Correct

User review is done to check that the requirements listed in the SRS are proper. SRS is correct if it meets all of the system's requirements.

  • Unambiguous

The SRS is considered unambiguous or precise if all requirements have only one interpretation. Some methods for avoiding ambiguity incorporate the use of modeling approaches such as ER diagrams, thorough reviews and buddy checks, and so on.

  • Complete

The SRS is complete if it has the following components:

  1. All fundamental requirements (regardless of whether they are related to functionality, performance, design, restrictions, characteristics, or external interfaces)

  2. Definition of the software's reactions to all realizable input data classes in all possible scenario categories.

  3. Complete labeling and references to all figures, tables, and diagrams in the SRS, as well as definitions of all terms and units of measurement.

  • Consistent

The SRS is said to be consistent if no subset of the requirements has a conflict. There can be three kinds of conflicts in an SRS:

  1. The properties of real-world objects may clash. For example, One condition may require that a particular value be less than 100, while another requires greater than 150.

  2. A reasonable or temporal conflict may exist between the two indicated actions. For example,

    • one requirement may need that the software adds A and B, while another may require that it concatenates them.

    • one condition may require that A always come after B, while another needs that A and B co-occur.

  3. Two or more requirements may define the same real-world object but refer to it differently. Consistency is promoted by the use of uniform terminology and descriptions.

  • Ranked for importance and/or stability

The SRS should be ranked for importance and stability. This can be done by associating an identifier to each requirement, indicating its relevance or stability. In most cases, not all requirements are equally critical. For example, some prerequisites, particularly for life-critical applications, may be required, while others may be just desirable. To make these distinctions plain and explicit, each element should be identified. Another method for ranking needs is to categorize elements as essential, conditional, or optional. Every requirement is crucial; however, some are urgent and must be met before other criteria, while others may be delayed.

  • Verifiable

We should be able to verify the specified requirements with a cost-effective approach to check whether the final software meets those requirements. The requirements are verified with the help of software reviews.

  • Modifiable/Adaptable

SRS should be made as adaptable as possible, with the ability to make changes to the system fast. In addition, changes should be fully indexed and cross-referenced.

  • Traceable

The SRS is traceable if the origin of each requirement is clear and if it facilitates the referencing of each condition in the future. Traceability is classified into two types:

  1. Backward Traceability: This is contingent on each need explicitly citing its source in previous publications.

  2. Forward Traceability: This depends on each SRS element having a unique name or reference number. When the software product enters the operation and maintenance phase, forward traceability of the SRS becomes especially important. As the code and design documents are changed, it is vital to determine the entire range of requirements that may be affected by those changes.

  • Design Independent

The final system should include the option of selecting from numerous design possibilities. More particularly, no implementation details should be included in the SRS.

  • Testable

An SRS document should be constructed so that it is simple to build test cases and test plans.

  • Abstract to the Right Level

The details should be explained explicitly if the SRS is written for the requirements phase. A feasibility study, on the other hand, can employ fewer details. As a result, the level of abstraction varies depending on the SRS's objective.

  • Customer-friendly

An end user may not be an expert in software engineering. As a result, formal notations and symbols should be avoided as far as possible and practicable. Instead, the language should be simple and straightforward.

Properties of a Good SRS Report

  • Concise

The SRS report should be concise yet unambiguous, consistent, and comprehensive. Verbose and irrelevant descriptions reduce readability and increase the possibility of errors.

  • Well-Structured

It must be well-structured. A well-structured document is easy to comprehend and alter. The SRS document is revised multiple times to meet the users' needs. User requirements frequently evolve. As a result, the report must be well-structured so that the process of making changes to the SRS document is as simple as possible.

  • Black-Box View

The SRS document should only define what the system should do, not how it should accomplish it. This means that the SRS document should describe the system's outward behavior rather than discussing implementation details. The SRS report should treat the system to be developed as a black box and define the system's externally visible behavior. As a result, the SRS report is often known as a system's black-box specification.

  • Conceptual Integrity

It should demonstrate conceptual integrity so that the reader may simply understand it.

Response to undesired events. It should define permissible responses to unfavorable events. This is referred to as the system's response to unusual conditions.

Types of Requirements in SRS

Types of Requirements in SRS

  • Functional Requirements

This section clearly explains the functioning of a software system, covering all possible behavior. All functional requirements, which involve calculations, data processing, and so on, are listed according to their priorities.

  • Performance Requirements

This section explains how a software system should perform on certain performance parameters while performing the required operations under specified conditions. It also describes the required time, memory, maximum error rate, etc.

  • Interface Requirements

Software interfaces are fully described and discussed in this section, which means how software programs communicate with one another or users in the form of any language, code, or message. Examples include shared memory, data streams, and so on.

  • Non-Functional Requirements

They describe the general properties of a system, also known as quality attributes. They include Security, Safety, Portability, Reliability, Reusability, Application compatibility, Data integrity, Scalability, resource requirements, and other quality attributes.

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  • The SRS (software requirements specification) document fully describes what the software product will do and how it will be expected to perform.
  • An SRS reduces the time and effort necessary by developers to accomplish desired results, as well as the development cost.
  • It specifies how an application will engage with system hardware, other programs, and users in a wide range of real-world scenarios.
  • Poorly specified requirements inevitably lead to delayed delivery time, inefficient usage of resources, some functionality being missed in the application, and various other problems.
  • The SRS document should be objectively correct, unambiguous, complete, consistent, ranked for importance and stability, verifiable, modifiable, traceable, design independent, testable, abstract to the right level, and customer friendly.
  • The SRS should cover all functional, non-functional, interface, and performance requirements of the software product.