The software development process requires much time and effort from all team members. Still, even the best experts can face inaccuracies in the process of gathering requirements, and this is one of the top causes of project failure. An inadequate specification can make your application less functional and successful than expected. However, you can avoid these misunderstandings by developing a good software requirements specification from the beginning. With well-written requirements, software engineering becomes easier for everyone involved.
Check out this guide to learn more about software requirements specification in software engineering:
Whether you are a digital product owner, startup founder, or project manager, this information will be handy for your business. Your team will benefit much from SRS documentation, so don't miss this opportunity to improve your knowledge of the process.
To understand how to create a good software requirements specification document, let’s start with the requirements document definition. This article will provide you with the best-understood answer to the question, "What is SRS?"
A software requirements specification, or acronym SRS, is a document that outlines the software requirements of your project. It consists of several sections that define what features and functions your system requires. Software requirement documents are not concerned with the technical aspect of software development as much as with the functionality of the software and the customer’s requirements. Thus, the design documents can help to solve all types of issues related to the behavior of a software application.
A software requirements specification defines the essential business processes that the system must support. As well as this, it allows digital product owners to decide what key parameters should be met. This document can comprise different elements, depending on the implemented methodology. But in general, the main components of SRS are:
Having read this software requirements specification definition, what are the advantages of having an SRS? The main benefit of a detailed software requirement document is that it enables clear communication with a client.
A well-formed SRS helps you to identify and gather all the necessary details about a particular industry, so you can avoid delays and extra expenses later on. SRS documents can also help startup founders to set clear company goals.
A well-written software requirement specification is key to your system's success. Every digital product owner can create a well-designed plan for efficient software development. Moreover, with the proper software requirement documentation, you can reach all business goals.
SRS documents allow product owners and stakeholders to share their specific product expectations. What does this mean in practice? The software requirements documentation tells the team which elements of the system need to be prioritized. This ensures the quality, efficiency, and reliability of the software functionality and performance criteria.
The requirements documentation in software engineering enhances clear communication between customer and client in several ways:
Whichever software development methodologies you are using, SRS documentation must always be a part of your project. By outlining the essential aspects of your project in detail, you can avoid many mistakes in software development.
After you identify the priority goals of your software requirements, you will need some information about the SRS users. Some people think that writing SRS documents is only for technical writers. But in fact, this is completely untrue.
Many different specialists take part in preparing software requirements documentation. Business analysts (BAs), project managers (PMs), software engineers, designers, QA/QC engineers, customers, and investors are an integral part of the SRS creation. Each of them has a significant role in the process.
For example, designers and QA engineers work on the system’s functionality and maintenance. BAs, PMs, and software engineers focus on project development from different angles. At the same time, investors use the SRS documentation for making decisions about further investments. With the software requirements clearly defined, customers, in turn, can check whether the company meets its business goals.
It’s important to realize that even though “software” and “system” requirements can have the same abbreviation, they do have different meanings. A software requirements specification (SRS) describes a piece of software that will be developed. As for the system requirements specification (SRS or SyRS), it details the requirements of an entire system.
Here is a handy comparison of these two requirements documents:
A software requirements doc is a tool for communication between software designers and stakeholders. Therefore, the two main participants in the SRS creation process are the contractor and the customer. The customer usually takes the most responsibility for the documentation.
Sometimes, a customer has no idea exactly how the project must look. In other cases, he has too many ideas. In either case, cooperation with the contractor will help you to understand exactly what is needed and create the proper documentation.
There are several characteristics you must keep in mind when writing SRS document for your project. Look through this list and compare it to your software requirements to ensure you tick every box:
Good SRS design creates the groundwork for software development. Thus, you will need to write a functional requirements document first to input into the SRS and enable you to launch a successful digital product.
Check out our guide below on how to prepare documentation for a software project. Then, start planning the steps necessary for your software project requirements analysis.
The software requirements specification must have a clear and understandable structure. To help achieve this, you can use an SRS document template with an approximate outline and make your own adjustments before approving its final version.
However you create it, a good outline is crucial to the whole software development process. It helps avoid wasting developers’ time and effort reading unnecessary information. Furthermore, it minimizes the risk of excluding valuable data from the process.
Ensure your SRS document includes three main parts: introduction, overall description, and system features and requirements. You can learn more about the best SRS document example in the next section of this article.
This stage requires an excellent user requirements document, for which you will also need to identify your project's purposes. Flesh out the main goals you plan to achieve and describe them in detail. Next, figure out your target audience and how they could use your product or application.
Structure the description of purposes using the following process:
You could begin this stage by outlining your assumptions regarding the functionality of your project. This will make it easier to define the right goals and start working towards them.
Another essential part of all user requirement specifications and SRS documentation is the detailed overview. In this stage, you will need to give an in-depth description of the project you're ultimately going to create. Mention all functions and features of the software and define how they will fit users' needs and expectations.
After writing the general description of your software, it is time to define its specific requirements. Outlining the various types of requirements in software engineering is probably the most vital part of the process. By detailing the functional requirements of your project, you provide developers with everything necessary to complete their job. Try to describe the way a user will use your application as vividly as possible.
Once you have fulfilled these four steps of how to write functional requirements, you are on your way to completing the software requirements specification. The next step is to get approval from the stakeholders.
Describe the SRS documentation in detail to capture investors' interest. Make a full-fledged presentation to showcase all the processes within the project. Keep in mind that the stakeholders can ask for some changes, so be ready to update the software requirements at this point.
Once you have gathered all required information according to the steps given above, you are ready to begin writing the SRS document. Understanding the SRS structure is key to defining the purpose and nature of a software product or application to be developed. Each fragment of the software requirement doc will come in handy during the project.
Check out this scheme to define what a typical SRS document includes:
To ease you in creating an SRS document, we have prepared a description of each section. Look at the summary of each section to understand the document’s structure.
The structure of the SRS document begins with an introduction. This section illustrates the overall software requirements along with their scope for your team.
This subsection communicates the purpose of the SRS document. It includes the types of requirements described in the document and a list of the people who will work with it. A few paragraphs will be enough to discuss the goals of your SRS documentation.
List all the team members and stakeholders who will take part in the SRS document creation and those who will have access to the completed document. Describe their roles to identify each one's responsibilities within the project.
Identify the cases in which your team will use the software requirements specification:
This subsection provides a brief representation of the system. You can describe the project from a more technical angle, mentioning its functionality and positioning.
Illustrate the users that are expected to interact with the system. Explain why this software development solution is unique. Thus, you will be able to interest stakeholders and gain more investments in your project.
Describe all specific terms mentioned in the requirements documentation in software engineering, to avoid misunderstandings with new developers. Name business entities and stakeholders with a particular abbreviation to speed up the process of SRS creation.
The second section informs the parties about the system's scope and functionality.
Unlike the previous subsections, this one can be omitted from the SRS. However, if you want to outline the user problems that you intend to solve, it is better to add this part, as it will be helpful during brainstorming.
Describe your assumptions towards the product development to see its possible ways of growth. This is how you can focus on the main aspects of your project's functionality.
The third section comprises the product functionality descriptions, along with its execution criteria. The following sub-categories can break this part down:
Functional requirements are product features or functions that must be implemented. Make a list of all functional system requirements for both developers and stakeholders. Start with defining the most vital functions, and then illustrate all details of each feature. Don't focus on the technical aspects of the product functionality; rather, characterize its features from the users' perspective.
There are four types of external interface requirements you can use for your project:
External interface requirements illustrate how the application will appear from the client's perspective. The list of these requirements may involve various design elements needed for product development.
System requirements in software engineering are the characteristics and limitations necessary for product performance. The SRS hardware requirements typically vary from minimal to the maximal value. This process can be challenging, especially at the beginning of product development. However, you can't miss this step out, as all developers have to meet the hardware standards.
Whereas functional requirements describe what a system should do, non-functional requirements outline how the system must behave. They describe quality attributes of the system that limit functionality. This section comprises features such as security, usability, and performance thresholds.
Considering the number of ways to define the client’s needs and wants, it would be overwhelming to use them all. Furthermore, methods that fit one project well may be less useful for others. So, it is crucial to find the most productive and beneficial methods for your project when creating an SRS document. Check out the best techniques you can apply to your software specification document:
The crucial goal of the software requirements specification in software engineering is to be clear and unambiguous. But how to create understandable SRS documentation? Collect and organize the information using specific pre-established tools to create a visual representation. Apply one of these practical frameworks right away: read on to learn more about them.
The context diagram comprises essential and additional parts of the project. It can be used for collecting all the existing elements into a bigger picture to see the system as a whole.
Forget about scanning huge documents full of technical software product specifications. With this SRS tool, you can instantly get a clear visualization of the future project.
The visual characteristics of this SRS tool are similar to the context diagram. Yet, their structural principles differ significantly. With functional decomposition, you can split the system functionality into smaller structural parts.
The main advantage of this tool is the ability to define the most meaningful features. Thus, you will get a clear understanding of the dependencies of the functions within the system.
Unlike the previous software requirements specification tools, this one focuses on the system functionality. A use case diagram showcases interaction between users and features. Using it for your software engineering documentation, you can build the “User Needs” section.
Want to see how functionality in the system can interact and develop in the future? Sequence diagrams can showcase this process in detail. Use this software requirements tool to define how a given function or feature changes over time or in response to different user inputs.
The purpose of these two diagrams is to show how various business processes influence software functionality. These process models also describe the users, middlemen, and final stakeholders' development perspectives. The AS-IS diagram illustrates current techniques for identifying all possible risks and problems. The TO-BE model showcases the ways of transforming and improving the existing software processes.
This software requirements specification tool illustrates actions that can be performed with the software. Using this method implies a multi-step process that starts with creating a user account. Thanks to such an approach, you can check a series of user cases like setting up a profile, confirming emails, etc.
Epic user stories access entire blocks of the software functionality. Split a sizable epic story into several smaller ones by means of decomposition, to maintain the SRS’s document readability.
As a rule, this SRS tool is applied during brainstorming for better teamwork interaction. All members of your team can use it in real-time for creating an up-to-date SRS mind map. Implement this method in each section of the software documentation to define its most critical components.
There are many software requirements specification templates on the web. Even so, we highly recommend you to check out the following example. Look through this description of an SRS document structure for an eChat app, to create a picture of your future project.
The introduction of this software requirements specification example comprises:
The document illustrates a detailed project plan for the efficient development of the eChat app. All the team members, including developers, designers, and testers, will understand how to develop the product.
The “eChat” is a perfect solution for remote workers. This application combines text and video chats, meaning people can use it for conferences and meetings.
The project is targeted at a narrow range of clients. The main customers of eChat are expected to be enterprise companies.
Here are some user requirements specification examples that you can use for your functional requirement document:
The “eChat” developers will be responsible for writing all the code for the app and developing the database.
If you are looking for a good interface requirement specification example, check out this list of requirements:
This concludes our example of SRS documentation for an “eChat” app. Now let’s have a look at how developing an SRS document fits within a Software Development Life Cycle.
Software requirements specification provides QA engineers with straightforward tasks. Thanks to this specification, developers understand how to make test cases, and technical writers create user manuals.
However, not all digital product owners know that SRS creation may differ depending on which development life cycle you are using. (You can learn more information about SDLCs in our guide to software development life cycle models.) But now, let's define how some popular SDLC models affect the way an SRS document is developed:
Waterfall. This option is perfect for less experienced developer teams. The waterfall model doesn’t require a fast pace; in fact, it allocates more time for writing an SRS document. If you require detailed requirements for your project, you should use this SDLC.
Agile. Such a model implies that a Business Analyst will be constantly updating the SRS document. This option fits companies that are planning to test every software requirements model and make frequent changes.
Scrum. With this model, you can develop the SRS doc very quickly. Thus, it is perfect for skilled developers. Such an approach allows a product owner to focus on this one long-term project.
Now you have read all the information about what is SRS and why it is so essential for your software development. After learning from this article how to write a requirements document, you can create a detailed specification that will set efficient communication with your team and customers right from the beginning. Apply the techniques mentioned here to build excellent SRS documentation right away.
If you liked this article, then check our pieces about writing a request for proposal (RFP), creating a roadmap, and everything you need to know about technical documentation.
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Roman Zomko
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