SysML Requirement Diagrams
SysML Requirement Diagram
Welcome to our SysML Requirement Diagram page, where we will explore one of the most critical components of the SysML language. The Requirement Diagram is an essential tool for capturing and managing system requirements, providing a clear understanding of the functional and non-functional requirements for a system.
The Requirement Diagram ties into both the SysML Behavioral and SysML Structural Diagrams by providing a link between the system requirements and the system's structure and behavior. This connection ensures that the system design aligns with the system's requirements, ensuring that the final product meets the customer's needs.
The Requirement Diagram provides a structured approach to capturing system requirements, enabling engineers to identify and track requirements, prioritize them, and ensure they are met throughout the design process. It is especially useful in complex systems where requirements may be interdependent or difficult to track.
On this page, we will provide an overview of the SysML Requirement Diagram, explaining what it is, why it's important, and how it fits into the larger MBSE and Digital Engineering landscape. We will also provide examples of how the Requirement Diagram can be used to capture and manage system requirements.
Whether you are a systems engineer, a modeler, or a project manager, our guide will provide you with a deep understanding of the SysML Requirement Diagram, and how it can help you ensure that your systems meet the requirements of your customers. So, if you want to learn more about SysML Requirement Diagrams, you have come to the right place.
Requirement Related
9. Requirements Diagrams (req)
What the system shall do
Requirement decomposition
An Intro to SysML Requirement Diagrams
SysML requirement diagrams are used to graphically illustrate requirements for a system. The diagrams provide a way to organize and visualize system requirements in a way that is easy to understand. They are useful for stakeholders to understand the scope of the project and for developers to design the system based on the requirements.
SysML requirement diagrams include elements such as actors, use cases, requirements, and relationships. Actors are the stakeholders that interact with the system. Use cases define the goals and tasks of the system. Requirements are user-defined conditions that must be met for the system to function as intended. Relationships are links between elements that represent constraints or relationships between them.
The diagrams are used to capture the system requirements and help stakeholders visualize them. They can be used to create a holistic view of the system, identify potential risks and issues, and map out the system architecture. They can also be used to drive development by providing a visual representation of the system's components and how they interact. They are also helpful in identifying any gaps or inconsistencies in the system requirements.
SysML requirement diagrams provide a way of organizing and visualizing system requirements that is easy to understand. They are useful for stakeholders to understand the scope of the project and for developers to design the system based on the requirements.
Requirements Diagram (req) Example
The coloring scheme of the diagram above is the SysML representation within the Cameo tool. The diagrams below are excerpts from "OMG Systems Modeling Language (OMG SysML) Version 1.4 and will give examples about the syntax of the language. Download the book here. For more helpful resources, go here.
Requirements Diagrams (req)
What is a SysML Requirement diagram?
Definition 1:
Requirement diagram (req): A SysML Requirement diagram is a static structural diagram that shows the relationships among Requirement («requirement») constructs, model elements that Satisfy («satisfy» Dependency) them, and Test Cases that Verify («verify» Dependency) them.
Definition 2:
The Requirements diagram is used to create and view Requirements and their relationships to other elements, including other Requirements. Requirements can be specified at any level, from strategic enterprise or business requirements through stakeholder requirements down to low-level engineering and even software and transition requirements.
The elements contained in this diagram can be viewed in a number of different ways, including:
Specification View - allowing the elements and their notes to be displayed in word processor or spreadsheet format in a separate dockable window
Inline Specification View - allowing the diagram and a list of its elements in a narrative form to be viewed side-by-side
List View - allowing the diagram elements to be viewed in a list that can be sorted and the elements grouped by properties
Gantt View - allowing the diagram elements to be represented on a Gantt chart showing how resources are utilized over time
When to use a Requirements Diagram
The Requirements diagram can be used to show a hierarchy of requirements using the containment relationship allowing a viewer to see how the structural relationships of the requirements. It is however most compelling when Requirements are viewed in a diagram with other elements using other relationships including other requirements. An example of this is the relationship between Requirements and Test Cases or Requirements and the Components of a solution.
What is the purpose of a Requirements Diagram?
The purpose of Requirement diagrams is to specify both Functional and Non-Functional Requirements within the model so that they can be traced to other model elements that Satisfy them and Test Cases that Verify them.
https://sysml.org/sysml-faq/what-is-requirement-diagram.html
Elements of a Requirement Diagram
Requirement: A Requirement (notation: rectangle with «requirement» keyword) is a capability or condition that a system must ("shall") satisfy. A Functional Requirement (functionalRequirement» keyword) specifies a function that a system must perform, whereas a Non-Functional Requirement (NFR) specifies quality criteria that can be used to test the effectiveness of system functions.
SysML predefines the following stereotype specializations of NFRs:
«performanceRequirement»
«interfaceRequirement»
«designConstraint»
«physicalRequirement»
Elements
The main elements that can appear in Requirements diagrams are:
Requirement
Test Case
The main connectors that can appear in Requirements diagrams are:
Containment
Trace
Copy
Derive
Verify
Refine
Satisfy
Requirement Relationships
This diagram shows that DerviveReqt, Verify, Copy, and Satisfy relationships are types of a Trace relationship. This inherently means that the DerviveReqt, Verify, Copy, and Satisfy relationships inherit properties from the Trace relationship. Note: The trace relationship is the weakest relationship in of all these relationships on the diagram.
