Requirement specification

Traditional requirements definition, also known as documentation, is the process of capturing all system and user requirements in a document. The requirements must be clear, complete, comprehensive, and consistent.  

During the specification activity, all requirements are collected from various sources. During the analysis and negotiation activities, these requirements are analyzed and understood. A formal document is then produced explaining these requirements. This is the requirements definition. More specifically, it is the process of documenting all user and system needs and constraints in a clear and precise way.  

Requirements definition is a challenging process, but it is a fundamental prerequisite for a successful information system procurement. At its best, it saves costs, speeds up programmer turnaround and enables the required needs and objectives to be met.  

Agile challenges traditional requirements definition. Because it is challenging to predict the future, the way and scope of requirements gathering must change. There needs to be a shift from up-front requirements definition to goal-driven continuous definition. The key to agile specification is to first understand the goals and the big picture, to find smaller but still valuable and useful entities within even large projects, and to specify the exact requirements only at the appropriate moment closer to the actual development work.  

Do you want to learn the principles of requirements definition or develop your skills in agile requirements definition and project work? Tieturi offers a wide range of requirements engineering training courses!

What are the benefits of requirements definition?

Among other things, requirements definition can help to save costs, speed up the turnaround of programs and ensure the delivery of all required features. The benefits of requirements definition include:  

Helping ensure all stakeholders understand the system being developed. This avoids misunderstandings at later stages of development.  

Avoids confusion between the requirements and the specification, thus avoiding unnecessary uncertainties during the development process.  

Helps to identify gaps in requirements at an early stage.  

Reduces the overall cost and time of development by avoiding rework due to changes in requirements.  

Types of specifications

There are many different perspectives to consider when defining requirements, whether working in a traditional document-driven way or using agile approaches. Roughly speaking, different requirements can be listed as either user or system requirements, as well as functional (what the system does) and non-functional (system criteria that are “invisible” to the user, such as performance, scalability, compatibility) requirements. The several types of requirements are described in more detail below:  

Functional Requirement Specification (FRS) 

Functional Requirement Specification (RFS) The functions that the system must be able to perform. In Agile, often described in terms of user/business needs and challenges, for example in a user story format.  

Performance Requirement Specification (PRS) 

Includes aspects and needs related to the performance of the system (e.g., response times, data rates, scalability, etc.). In the Agile approach, the key performance requirements are linked to a Definition of Deliverables (DoD) to ensure a high-quality final output.  

Configurations Requirement Specification (CRS) 

A document that summarizes all the information related to the configuration of a system. It includes, for example, supported platforms, software/hardware dependencies, minimum system requirements, etc.  

Business Requirements Specification (BRS) 

Describes the business aspects of the system and how they affect the business of the system. In Agile, these can be described, for example, as part of the project objectives or imported as part of the Definition of the Done Deal (DoD).  

Reliability requirement specification (RRF) 

Summarizes information related to the reliability of the system, such as availability, recovery time, error rates, etc. In Agile, they are often part of the DoD or a separate standard that must be followed as part of the build.  

Compatibility Requirement Specifications (CRF) 

Contains all information related to the compatibility of the system, such as supported platforms, software/hardware dependencies, minimum system requirements, etc. In Agile, compatibility is considered as part of the process and often brought into the Definition of Done (DoD)  

Software Requirement Specifications (SRS) 

Software aspects of a system, such as functionality, performance, and scalability. In agility, these issues are addressed either in the descriptions of the individual tasks in the development pipeline or in the DoD.  

New lessons for requirements definition

Looking for agile requirements specification training or information system implementation training? Tieturi offers a wide range of requirements engineering training courses! All our trainers are experienced and offer you tips for engineering requirements taken from the working world.  

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