Why Model Requirements? | the-requirements-engineer.com

In the world of software development, clear and precise requirements build successful projects. They serve as a blueprint, guiding developers and stakeholders toward a common goal. Traditionally, texts document requirements, but an increasingly popular method is to model these requirements. This article dives into the reasons why modeling requirements can be advantageous, comparing textual and modeled requirements, and discussing the pros and cons of each approach. Learn why to model requirements.

Table of Contents

Examplified comparison

The following example shows an introductory comparison of textual and modeled requirements:

Textual requirements

The user interface shall display the contact form.
After completing the “Show contact form” action or after completing the “Show error” action, the system should offer the user the opportunity to enter data.
After completing the “Enter data” action and provided the data is activated, the system saves the data.
After the “Enter data” action and if the data is incorrect, the system displays an error message.

Modeled requirements

Understanding Textual Requirements

Textual requirements are written descriptions of what the software system should do. They include functional requirements (what the system should do), non-functional requirements (how the system should perform), and constraints. These requirements are usually compiled into a (software) requirements specification document.

Advantages of Textual Requirements

Simplicity: Textual requirements can be simple. Textual requirements are straightforward to write and understand.
Flexibility: Textual requirements can be flexibel. They can easily accommodate changes and additions.
Universality: Textual requirements can be universal. Almost everyone can read and understand text, making it accessible to all stakeholders, regardless of technical expertise.

Disadvantages of Textual Requirements

Ambiguity: Textual requirements can be confusing and conflating. Text can be interpreted in multiple ways, leading to misunderstandings.
Lack of Structure: Textual requirements can occur unstructured. Large volumes of text can become disorganized, making it difficult to find specific information.
Complexity Handling: Textual requirements can be too complex. Describing complex interactions and processes in text can be cumbersome and hard to follow.

Exploring Modeled Requirements

Modeled requirements involve using diagrams and visual representations to capture the system’s requirements. Common modeling languages include Unified Modeling Language (UML), Business Process Model and Notation (BPMN), and Systems Modeling Language (SysML).

Advantages of Modeled Requirements

Clarity and Precision: Modeled requirements are clear and precise. Visual models reduce ambiguity by providing a clear, concise depiction of system requirements.
Structure and Organization: Modeles requirements are structured and organized. Models provide a well-organized framework, making it easier to manage complex requirements.
Enhanced Understanding: Modeled requirements enhance understanding (of complex issues). Diagrams and models help stakeholders to visualize the system, making it easier to understand complex interactions and dependencies.
Better Communication: Modeled requirements allow a better communication. Models can bridge the gap between technical and non-technical stakeholders, facilitating better communication.

Disadvantages of Modeled Requirements

Learning Curve: Modeled requirements can be difficult to understand firsthand. Stakeholders might need training to understand and use modeling languages effectively.
Tool Dependency: You need the tools of choice. Creating and maintaining models often require specialized tools and software.
Initial Time Investment: To be clear, precise, and so on you need to take the time to build the model. Building models can be time-consuming, especially at the beginning of a project.

The Case for Modeling Requirements

As software systems grow in complexity, the need for clear, structured, and easily understandable requirements becomes paramount. Modeling requirements offers a way to tackle this complexity head-on. By providing visual clarity, enhancing communication, and maintaining an organized structure, models serve as a powerful tool in the software development arsenal.

However, it’s essential to recognize that textual and modeled requirements are not mutually exclusive. A hybrid approach often works best, leveraging the strengths of both methods. Textual requirements can provide detailed descriptions and context. Models on the other hand offer clarity and precision for complex interactions and processes.

So why model requirements? In conclusion, the choice between textual and modeled requirements should be guided by the specific needs of the project, the complexity of the system, and the preferences of the stakeholders. Embracing modeling can significantly enhance the requirements engineering process, leading to more successful and manageable software development projects.

This text is based on content from the source: International Requirements Engineering Board (ireb.org). The International Requirements Engineering Board is the owner of the copyright.