The Essential Guide to Requirements Management and Traceability
How to write system requirement specification (SRS) documents
Imagine that you’re in charge of designing a 17-story building—but the blueprints are missing. Moving forward without this essential document would put the entire project at risk for serious errors. Launching a new software project is similar in that without a blueprint, you’ll likely produce a system that lacks the necessary software functionality and isn’t aligned with the customer’s needs. Clear requirements , such as those included in a system requirement specifications (SRS) document, create a foundation that ensures your team delivers the right product and avoids expensive reworks.
But where should you start? In this article, we’ll explain details about SRS documents and how to use them, and we’ll provide examples to get you on the path to success.
What is a System Requirements Specification (SRS)?
The System Requirements Specification ( SRS) is a document focused on what the software needs to do and how it must perform. It lays the important groundwork so that every person involved with the project understands the most crucial details.
An SRS outlines the behaviors, functions, and capabilities required of the system, along with any potential constraints. Functional and nonfunctional requirements are included. Design suggestions and information outside the customer’s requirements are not included.
Approval is received from all necessary stakeholders, showing that they clearly understand the project requirements and everyone agrees. In a sense, the SRS functions as an insurance policy that any party can refer to in case of uncertainty.
Why Use SRS Documents?
Using an SRS ensures that specifics around a project are crystal clear, reducing the risk of rework and wasted time. Important benefits of using this type of document include:
- Providing Valuable Customer Feedback. An SRS is the customer’s confirmation that your organization understands the problems that need to be solved and how the software must behave to address the challenges. Visuals such as charts and tables can provide additional clarity.
- Breaking Work Into Smaller Pieces. An SRS contains a large amount of information, but they ultimately break problems into smaller, more manageable parts.
- Serving as a Parent Document. The SRS serves as a parent document to any additional documents that follow its creation. The scope of work, software design specifications, and other documents often leverage what is highlighted in the SRS . Plus, it can serve as a product validation check. Did we do it right? Check the SRS.
The SRS assists with identifying problems earlier in the development process, which helps manage time more effectively. It’s far easier, for example, to update specifications before any development has begun, versus later in the process.
SRS Format: How is a System Requirements Specification Written?
Similar to following a recipe, there are several important components, or ingredients, in an SRS . A good SRS needs to answer a few critical questions, such as:
- What should the software do?
- How should it behave?
- What are the performance requirements?
- Are there any constraints that need to be noted? And if so, what are they?
A good starting point is an SRS outline . A rough outline of the various sections can help you get ready to fill in the important details. Consider the following:
- Create an Introduction. The introduction addresses what the software needs to do (and what it should not do). The development team and product owners should be involved in writing this part of the plan. Why does the product need to be built? What challenges does it solve? And who is going to use the product? Additionally, the SRS introduction might contain an overview of what is included within the document.
- Write a General Description. Focus on the functionality of the product. Define the required hardware and user interfaces. What do end users expect the software to do? What are the various functionalities? Ultimately, this section will focus on system interfaces, user interfaces, hardware interfaces, software interfaces and more. Additionally, any important assumptions need to be included.
- Include Specific Requirement Specifications. This section examines specific details about the product so it’s easier to design and validate that it has met requirements. It describes all inputs that the software must handle, highlights any required outcomes, and clearly defines any necessary integrations. Performance criteria should also be included, as well as any software system attributes, such as readability, availability, security, profitability, and more.
Once you have the basic outline, you can start filling it out with the help of your team and customer. Upon completion, get final approval. Everyone important to the project needs to review and approve the final version of the SRS.
The optimal organization of the requirements with in an SRS can vary greatly , depending on the system being developed, so there isn’t a one-size-fits-all template. However, a general software requirements specification template such as this one can be used to create the “bones” of your document. You can then fill in the details as you go.
What Mistakes Should be Avoided When Building a System Requirements Specification?
As you become more experienced at SRS development, the process will become much faster. When starting out, however, it helps to have a list of common mistakes to avoid. Consider the following:
- Failing to Include a Complete Dictionary. Does your SRS include jargon that only people in a specific industry understand? If so, create a dictionary section for easy viewing and include definitions of any terms not commonly understood.
- Creating Confusion by Mixing Concepts. Keep your document organized and be careful to present information to readers in a logical flow. Avoid mixing concepts throughout the document so that you don’t create confusion.
- Not Fully Understanding the End User. Who will interact with the software, and what are the expected results? For example, imagine that an application is supposed to generate reports. Some requirements may address how the user will click on a specific button to generate various reports. Ensure that you know what is expected from the report generation software, but also know who is clicking on that button so you better understand the user and the required functionality.
- Being Ambiguous. Ensure that your requirements can’t be misinterpreted. An SRS is designed to prevent misunderstanding, so make sure the document doesn’t generate it. For every functionality or situation description, make sure that you don’t present features that have not yet been defined.
