Behavior Diagrams for Model-Based Systems Engineering (MBSE): Sequence Diagrams
From the series: Behavior Diagrams for Model-Based Systems Engineering (MBSE)
This second part in the MBSE Behavior Diagrams series delves into sequence diagrams, which are ideal for systems with time-dependent interactions. These diagrams illustrate the order of interactions, decision points, and constraints, using lifelines and horizontal lines to represent component interactions. System Composer™ allows for the co-creation of sequence diagrams and architecture models, linking requirements and using real data for executable verification.
Published: 12 Aug 2024
Using diagrams to describe the system dynamics and how it should interact with its environment is one of the main advantages of model based systems engineering. Rather than creating just a visual depiction of the system behaviors, System Composer is tightly coupled with our modeling and simulation engines allowing for executable behavior diagrams. This helps to create implementable requirements and convey design intent to downstream functional teams. In this video, we will review sequence diagrams, when to use them, and how employing them in System Composer helps to ensure system engineering and design processes remain in sync.
Some systems have components whose interactions are best defined as time dependent, call and response style, exchanges of data, events, messages or service calls. Sequence diagrams provide semantics for representing the intended order of those interactions, as well as decision points for which interaction sequences should occur. In other words, they help to reduce the ambiguity of the system interactions. Because of this, they are often used to help refine requirements.
Components from an architecture model are depicted as lifelines consisting of a header box with a vertical line extending downward to show the passage of time. Horizontal lines from one lifeline to another represent potential event paths for connections between components and the architecture model. Those paths can be guarded by both a trigger, indicating the event has occurred, and a constraint, which the event must satisfy to enter the next part of the sequence.
For more complex interactions, fragments can be used to add block constraints to groups of events like loops and if else statements in software. System Composer enables you to create a digital thread with linking and traceability between all models, requirements, and diagrams.
Creating sequence diagrams in System Composer provides additional benefits, such as the ability to co-create sequence diagrams and architecture models at the same time adding flexibility to your workflow, use sequence diagrams to describe the behaviors of filtered architecture views so you can focus on just the pertinent parts, link requirements to diagram elements to ensure traceability from top to bottom, use the very same syntax corresponding to real data messages and service calls from your software models to streamline code implementation and generation, And most importantly, after linking your architecture to Matlab and Simulink designs, sequence diagrams become more than just a means of communication but an executable verification tool.
This is just a small overview of what is possible with sequence diagrams and System Composer. If you want to learn more. Visit our solutions page or dive into one of our examples. And don't forget to check out our other videos on behavior diagrams. Thanks for tuning in.