How to create requirements specifications for a software project that will be exceptionally clear to every provider?

| 9 min read

Often, business customers expect software development teams to be mind-readers, being able to create a product based on unspoken, malformed or even unknown requirements. Wrong or missing requirements, in their turn, can bring wrong or incomplete products regardless of how good the subsequent phases initially were.

Ultimately, to deliver a top-notch product, any software development company definitely needs a detailed requirements document as it lays a foundation for software engineering activities. Therefore, it might be said that the proper software requirements engineering document is like a magic wand for any software development team and the customer.  

Fancy writing software requirements specification that will make your team and the customer fall in love with? We’ve got you covered. Use this guide to be able to write a well-crafted software requirements specifications document and to evaluate whether the written document is of good quality or it lacks some critical information.

But at first, let’s take a more in-depth look at development project specifications:

 

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Typically, software requirements specifications (SRSs) are the written tech documents that offer the basic company’s understanding of a customer system requirements and dependencies before any actual design or development work. Indeed, a SRS should be developed during the first stages of any software development process. To put it simpler, the SRS for the software development project fully describes what the product should be capable of doing and how it will be expected to perform.

These are the main types of a software requirement specification document:

  • Business
  • Stakeholders
  • Product, which can be:

Functional ( when it specifies a behaviour/function, for instance to show the name, free space or format of the flash drive connected to the USB port.)

Non-functional (it describes how, how well or to what standard every particular feature should be provided. For instance, security and access requirements or the needed interfacing with users' and other systems.)

  • Quality

Wondering why is there any need it SRSs? Consider these two points:

  • A software requirements specification acts as a two-way insurance policy that guarantees that both the customer and the software vendor clearly understand the required scope of work and needed functionality.
  • Essentially, it also enables software developers to consider user requirements before the designing of the system commences, reducing the development effort in the long run.

 

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By default, a software requirements specification includes functional and nonfunctional requirements, without any kind of design suggestions. There are nine most common themes to address when creating an SRS:

  1. Interfaces
  2. Functional Capabilities
  3. Performance Levels
  4. Data Structures/Elements
  5. Safety
  6. Reliability
  7. Security/Privacy
  8. Quality
  9. Constraints and Limitations.

Software requirements specification should be devised in such a way that it’s pretty simple to write, review, and maintain them. By default, this kind of software document should be not only complete and accurate, but also efficient. Moreover, it should be 100% unambiguous. In other words, each of the requirements it possesses should have only one interpretation. Moreover, both the developer and the client should be able to easily understand it.

There are many different methods in requirement spec writing.  Cost and time are the key criteria when determining which method to use.  However, that is not all when it comes to a good software requirement document. As a matter of fact, developing a software requirements document is a long, time-consuming process. Below, you will see some solid practices on how to properly write a good SRS document for a software product, and how to properly gather and analyze the requirements the software project should include.

These are the main steps you have to do to have a good SPS at the end:

  • Requirements elicitation
  • Analysis of the requirements
  • Validation
  • Documentation

Do you know any important gathering techniques? They may vary depending on the situation and constraints, but using a combination of them to supplement each other will help in achieving complete requirements.

Most of the requirements documents elicitation consist of the following stages/methods:

  1. Brainstorming
  2. Document analysis and review of existing documentation
  3. Focus groups
  4. Interface analysis and external interface analysis
  5. Interviews
  6. Observation/job shadowing
  7. Prototyping (storyboarding, navigation flow, paper prototyping and screen flows)
  8. Requirements workshops
  9. Surveys/questionnaires.

As a matter of fact, developing a software requirements document is a long, time-consuming process. Below, you will see some solid practices on how to properly write a good SRS document for a software product, and how to properly gather and analyze the requirements the software project should include.

When it comes to specifications gathering and analysis, this process is rather tough as every specifications feature should be checked from all possible ways.  Just to the record, there are cases when different requirements have different terms to refer to the same object.

Another important thing to keep in mind upon gathering requirements is that a good SRS should be tolerant towards incompleteness and complexity. Pay attention to the ultimate features of the product, such as the type of software being developed and the approach used in its development.

Don’t assume that you understand everything, even if it does look apparent. A simple requirement, for instance, “create a blog” might mask all kinds of underlying assumptions, requirements. You need to clarify everything it might concern:

  • On what framework it should run?
  • What are the fields for a blog post?
  • How are authors managed?
  • Which features does it need? Maybe calendar or categories?
  • Is there a need in the comments section?
  • How are the posts displayed?
  • How should it be optimized?

To tell you the truth, there are dozens of questions to ask before getting started with such a simple matter in terms of web development as a blog design.

And now, let’s check the most crucial steps you need to follow if you deal with spec requirements analyses.

Key steps to follow when analyzing software requirements product specification:

  1. Determine what the software system has to do (detect all these features).
  2. Identify requirements by questioning like, Why, What, Who, How etc.
  3. Analyze how complex application would be and its impact on testing.
  4. Convert the spec business requirements into architectural and design requirements.
  5. Determine all things that you would need to test.
  6. Prepare, distribute, and analyze surveys.
  7. Determine the development lifecycle since the whole process of spec writing depends on this. For instance, projects using an iterative lifecycle include requirements development at every iteration whilst the agile methodology will need to perform requirements management on an ongoing basis.

Validation is a crucial stage for any requirements specification document. That is the stage when you need to check and validate all of the stated requirements for a software system. Ensure that it meets all specifications and fulfills its intended purpose.

In short, there are TWO main questions you should ask yourself at this stage:

  1. Does the product do what it is supposed to?
  2. Does the software meet all the requirements?

If yes, well done. If no, check what has gone wrong and think about the possible ways out. Once you’ve validated that the requirements specification paper satisfies needs and agreed upon expectation, proceed to documentation.

There are special templates for requirements specification documents. Choose which one suits your project the best or create your own. By default, templates can help you document everything in a consistent and straightforward way.

In short, these are the key steps to follow:

  • Create an SRS outline and choose the required template
  • Make sure to insert a complete description of the software’s purpose and functionality in your spec.
  • Finally, evaluate your SRS.

There are some tips to evaluate any SRC document. By keeping them in mind, you will be able to check if the particular software requirements PDF document you’ve just got is a good one or whether there some issues that can cause troubles.

Here are the key criteria to evaluate if the SRS document is clear and realistic:

  • It accomplishes four major goals:
    • Provides feedback to the customer
    • Offers the problem division into component parts
    • Can be used as an input to the design specification
    • Is the parent document for testing and validation strategies.
  • Every of its requirement is 100% unambiguous. No double meaning is allowed. Make sure everything is pretty straightforward.
  • It can be easily modified. Yep, that’s a really important issue since the user requirements might change and therefore, a good SRC should be created with this in mind. So, make sure that it’s pretty easy to modify the changes, consistently maintaining the structure and style of the SRS.
  • It is consistent. Ensure that the subsets of individual requirements defined do not in any way conflict with each other.
  • It is atomic. The specification offers such a detailed division of its components, so it’s impossible to separate the existing division into components.
  • It is prioritized. Every requirement should be prioritized, so that the team knows what is of first priority and what can be done later.
Tip: gather some information on how much of your own project effort is being spent on creating your software requirements development. Afterwards, judge how well that has worked for you in the past and you’ll be able to take advantage of this historical data when estimating the requirements effort needed for future projects.

The Bottom Line

Software requirements specification outlines the practical usage of the particular product or service, condition or capability to which a system conforms. By default, an SRS document is created when entire requirements are elicited and analyzed. There are many different methods in requirement spec writing. Poor requirements might have a crucial impact on the end results of systems or projects. Therefore, to ensure that your project has the proper SRS document, use this guide. It covers some tried-and-true techniques for creating good requirements for a software product and for evaluating the quality of the SRC.  

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