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Software Requirements Specification: How To Write It with Example
Measure seven times, cut once. This proverb is always topical. Before you do something, you need to be prepared to avoid failures, especially if you intend to create software.
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The software development cycle includes a few mandatory stages, and none of them can be ignored. The creation of SRS, or software requirements specification, must be highlighted since it is the document that the development team must rely on to build a website or mobile app.
Writing software requirements specification requires the involvement of business analysts, developers, system architects, and potential customers. Yes, it is not a mistake. Customers will help build a project that meets their needs. But first things first — this guide contains everything about SRS and how to write it (SRS template is also at your fingertips).
What Is Software Requirements Specification?
Software requirements specification (SRS) is a comprehensive description of the software that is planned to be developed. SRS includes use cases that describe all kinds of software interaction with users. Use cases are also known as functional requirements.
In addition to the use cases, the software requirements specification also contains non-functional requirements (or additional ones). We will review all types of requirements in detail below.
An SRS is a basis for further planning, design, and coding. Also, QA engineers use SRS while testing the product. However, an SRS doesn’t include a detailed description of design, development, or testing processes. Its goal is to determine the right development strategy and select the tech stack that will be used.
The Importance Of Software Requirement Specification
If you have an intention to create software, you can conduct market research and find out what needs to be done to release a competitive product. Also, you can build a list of features to be included in the mobile app/website. But if you are not a developer, you don’t know what to do next.
Therefore, you need to get in touch with a dependable and skilled software development company like Cadabra Studio that will do the most complicated job for you. A website like Clutch.co is an excellent option to find out everything about developers — it contains all information about the company and reviews from real clients.
Okay, you hired app developers, and then you need to make sure that all your requirements will be kept up. That is why it is crucial and required to create the software requirements specification document, where all details of the future project are stated.
Also, there is an article containing tips on how you can hire the best app developers. We recommend reading it.
The SRS document contains information about clients’ needs and particularities of the development process, what it must include depending on the project. Thus, an SRS helps developers and designers build a project that meets clients’ and owner’s needs. All participants of the development team get the required insights during the product creation process.
Besides, we want to add that the SRS document is a vital document to avoid any misunderstanding between development team members and customers. Moreover, this document is a must-have if you need to attract investments — your potential investors will need to get acquainted with the SRS document.
Learn more about tips on how to pitch an app idea and attract investments — there is an ultimate compilation of tips from Cadabra Studio.
How SRS Differs From A Brief And RFP
There are such conceptions as a development brief and a request for a proposal (RFP). These documents may also be created before starting the development. And the abundance of documents may confuse you, so we want to spell everything out.
A development brief is a basic description of your future plans and ideas you are going to make real in software. Simply put, our specialists interview you to obtain more information and use it as a starting point for the upcoming development process.
A request for a proposal (RFP) is usually created by a client since this is a request where they can indicate necessary details and clarify many issues for a development team.
Thus, a brief may be unnecessary if you write an RFP. If you don’t know how to write an RFP, you can also use our guide on how to create web development RFP as a tutorial — it contains an RFP template as well, that fits both web and mobile software.
Finally, an SRS document is an official approval for your project development that contains detailed technical and non-technical info about everything related to the project.
An SRS Layout: What It Includes
Although you will find the software requirements specification sample at the end of the article, we consider it necessary to make a bulleted list of the primary points your SRS must include.
The purpose of the project. Here you and the development team describe the software’s purpose and what it should do for users.
Description. This point includes data about the target audience, business goals, references, document conventions.
Software description. The product perspectives, features, user class, operating environment, constraints, and limitations (if there are).
Requirements. The SRS document includes such requirements as functional, non-functional, and external interface requirements. We will cover each of them in the next section.
Types Of Requirements In SRS
The SRS document must include three types of requirements: functional (or system), external interface requirements, and non-functional requirements.
Functional requirements describe what has to be done. They identify tasks or actions that must be implemented. These requirements determine steps the software must take and what it is capable of performing. It consists of design, graphics, operating system requirements, and constraints (if any).
External Interface Requirements
These requirements include user interfaces (interaction logic between software and user), screen layouts, buttons, functions on every screen, hardware interfaces (here a team describes what devices the software is created for), and other relevant particularities.
Also, software interfaces like frontend and backend stack, database management system, etc. must be included.
Non-functional requirements in the software development requirements document imply system functionality's general criteria, not individual use cases. Thus, they include performance requirements, safety and security requirements, safety quality attributes (adaptability, flexibility, usability, etc.).
If you don’t have any idea how to write down all these requirements properly — mind to drop us a line and we will provide you with timely assistance.
Techniques To Use When Creating SRS
The SRS document is usually created by business analysts, system architects in collaboration with a customer. But there are some tips on how to achieve the best results by applying existing methods.
Brainstorming. It's the most popular technique (that really works, by the way) when a group of people involved in software development shares their ideas to find the best solutions.
Interview. It implies both interviews between developers and a customer and between potential users. It is essential to clarify users’ needs clearly.
Prototyping. Typically, prototypes are created when an SRS is completed and approved. Still, a prototype is also an excellent option to provide the user group with a clickable product to test it and get their feedback. It will help designers and developers improve the product.
Mind mapping. All participants of the process build a visual map with a hierarchy of the system to see how all components interact.
Analysis of documents. The development team needs to analyze such documents as a business plan (if there is), current process flow, contractual agreements, etc. It allows developers to get more in-depth information about the future project.
By the way, a business plan creation is a challenging task that requires rapt attention, so we recommend you to read this article: How to Write a Business Plan for a Mobile App.
How To Write A Software Requirements Specification: Five Necessary Steps
What about the proper steps on how to write a software requirements document efficiently? Of course, we didn’t forget about them. Five necessary steps are usually followed during the SRS document creation. Let’s see them all.
Draw Up An Outline
First, you need to build an outline of the software requirements specification. It means that the SRS document structure doesn’t have a standardized template, so you can do it on your own or use the one that the software development company uses.
You can use existing templates that you find on the Internet, but we recommend entrusting the project to developers since they have enough experience in building an SRS.
Describe All The Details
This step is a time-consuming one, and here the assistance of the development team will be mandatory. You and developers fill out the outline and describe all nuances concerning the future development process.
It is worth noting that each detail must be precise for everybody involved in the process, so it is essential to avoid confusion. However, an experienced business analyst knows how to create a software requirements document wisely.
If the SRS document contains charts and infographics, images, etc. — it will be an added advantage for participants to capture the idea faster and get more clear insights into how this software must be developed. But don’t overdo with visualization — too many images (some of them may be unnecessary) won’t let development focus on vital elements.
All stakeholders need to review the SRS document and approve it. If everyone agrees with the intended development process, it is initiated right after the approval. It is recommended that all team members will read a specification. It will help ensure that everything is coherent for everybody.
Make The Specification Prepared For Amendments
Although everything is agreed upon and approved, some changes and updates are possible during the development process. All amendments must be available in the current version of the SRS documents, and all team members are to be notified about them immediately to stay up-to-date.
Aspects That Make An Excellent Software Requirements Document
Finally, we want to share some ideas on how to improve the SRS document. There are particularities you must follow when creating a specification. And you will find them below.
Easy-to-understand. Although it is already a clear-cut point we mentioned above, remember it once again. Any misunderstandings are impossible in your SRS document. Everyone must catch it right.
Comprehensiveness. The specification should contain enough information for software development. But mind to eliminate unnecessary components, and leave out all crucial details. The business analyst will help you single out all the required information.
Feasibility. The project has to be built on existing and used technologies. It means that an SRS shouldn’t contain a possible tech stack that uses upcoming tools that are not tested yet. Thus, the project must be fully-functional, even though it is not created yet.
Flexibility. That is what we meant when we told you about the prepared SRS. The world of software engineering is adaptive, and some things may change during the development process. Developers must be flexible and ready to apply another tool or technique while building the product. And all amendments must be reflected in the software requirements specification.
Consistency. All sections and requirements in your SRS must be coordinated, and they cannot contradict each other. All details must be thought out and logically connected.
Do you still have any questions or hesitation that concerns SRS? Contact us to get a free consultation.
A Software Requirements Specification Example
We have prepared a template of the software requirements specification you may use as an example for your future product.
It contains all the necessary steps and requirements we have covered in the article. You can look it through and download, following this link. However, some points can always be changed and adapted to the project's peculiarities.
Creating the SRS document is a must-have stage that the development team should think out if you don’t want to get the product failed. The software requirements specification is created to navigate the development team to the same result and build the software that meets future users' expectations.
If you don’t have enough time to figure out how to write a requirements document, you should collaborate with professionals like Cadabra Studio, who knows firsthand where to start and what to do.
Our staff includes mobile and web developers, UI/UX designers, project managers, QA engineers, business analysts, and other specialists.
You just need to contact the Cadabra Studio team for proceeding to the next steps. Our assistance would start right away.