4.1 Defining system architecture using models
4 min read•august 15, 2024
System architecture in MBSE is all about creating a blueprint for your system. It's like drawing up plans for a house, but instead of rooms and walls, you're mapping out components and how they work together.
This blueprint helps everyone on the project understand what you're building. It lets you spot potential issues early on and makes sure all the pieces fit together smoothly, saving time and headaches down the road.
System Architecture in MBSE
Fundamental Concepts and Purpose
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- System architecture defines the fundamental organization of a system encompassing components, relationships, and design principles within the Model-Based Systems Engineering (MBSE) framework
- Serves as a blueprint for system development providing a high-level abstraction of structure and behavior to guide detailed design and implementation
- Facilitates communication among stakeholders by presenting a unified view of the system's composition and functionality
- Enables early identification of potential design issues, trade-offs, and integration challenges before significant resource commitment
- Acts as a bridge between user requirements and system implementation ensuring traceability throughout the development lifecycle
- Supports system analysis and optimization allowing engineers to explore alternative architectural solutions and evaluate impact on performance, cost, and other key metrics
- Provides a foundation for model-based verification and validation activities enabling virtual system integration and testing
Architectural Views and Stakeholder Communication
- Utilizes multiple architectural views tailored for specific stakeholders or concerns (functional, physical, operational)
- Employs standardized modeling languages (, AADL) to create consistent and comprehensible representations
- Incorporates visual diagrams (block diagrams, interface diagrams) to illustrate system structure and relationships
- Includes textual descriptions and annotations to provide context and rationale for architectural decisions
- Supports generation of stakeholder-specific reports and documentation from the architectural model
- Enables interactive exploration of the architecture through model-based tools and simulations
- Facilitates collaborative review and feedback processes among diverse stakeholder groups (engineers, managers, customers)
Elements of a System Architecture Model
Structural and Behavioral Components
- Structural elements define the physical or logical organization of the system (components, subsystems, )
- Behavioral elements describe how the system operates and responds to stimuli (functions, processes, states)
- Allocation relationships map between structural and behavioral elements showing how functions are assigned to components
- Hierarchical decomposition represents the system at different levels of abstraction from high-level concepts to detailed subsystem designs
- Interfaces and connections specify how system elements interact and exchange information or resources
- Architectural patterns and styles apply reusable design solutions and best practices to address common challenges (layered architecture, service-oriented architecture)
Modeling Techniques and Representations
- Use of modeling languages (SysML) to formally describe system architecture elements and relationships
- Employment of diagramming techniques (block definition diagrams, internal block diagrams) to visualize system structure
- Utilization of behavior modeling notations (state machines, activity diagrams) to represent system dynamics
- Application of interface definition languages (IDL) to specify component interactions and data exchanges
- Incorporation of parametric diagrams to capture constraints and equations governing system behavior
- Implementation of traceability matrices to link architectural elements to requirements and other artifacts
- Utilization of model repositories and version control systems to manage architectural model evolution
System Architecture for Design and Development
Design Support and Analysis
- Provides a common reference for all stakeholders ensuring a shared understanding of system structure and behavior throughout development
- Enables early validation of system concepts and requirements allowing identification and resolution of design issues before they become costly
- Facilitates trade-off analysis by providing a framework for evaluating alternative design solutions against requirements and constraints
- Supports modular design and development by clearly defining system boundaries, interfaces, and dependencies between components
- Enables virtual integration and testing allowing simulation of system behavior and performance before physical prototype construction
- Provides a basis for generating lower-level design artifacts (detailed component specifications, interface control documents)
- Supports change impact analysis by allowing assessment of ripple effects from proposed modifications across the entire system
Development Process Integration
- Guides the creation of work breakdown structures and project schedules based on architectural decomposition
- Informs resource allocation and team organization by identifying subsystem boundaries and interfaces
- Supports risk management by highlighting critical system elements and potential integration challenges
- Facilitates parallel development efforts by clearly defining component interfaces and dependencies
- Enables incremental system development and integration strategies based on architectural modularity
- Supports configuration management by providing a structured framework for tracking system variants and versions
- Guides the development of system verification and validation plans based on architectural elements and relationships
System Architecture vs Other MBSE Models
Relationships with Requirements and Functional Models
- Requirements models link to system architecture models ensuring architectural decisions satisfy
- System architecture models derive from and maintain traceability to system requirements
- Architecture models incorporate and refine functional models allocating functions to specific structural elements
- Functional analysis informs architectural decisions on component organization and interfaces
- Architecture models provide context for elaborating detailed functional specifications
- Requirements and functional models evolve iteratively with architecture models throughout the development lifecycle
Integration with Behavioral and Performance Models
- System architecture provides context for detailed behavioral models (state machines, activity diagrams)
- Behavioral models elaborate on the dynamic aspects of architectural elements and their interactions
- Architecture models inform and constrain performance models by defining system structure and interactions influencing system-level performance
- Performance models provide feedback to refine and optimize architectural decisions
- System architecture establishes the framework for parametric models defining relationships between system parameters and constraints
- Parametric models support quantitative analysis and optimization of architectural alternatives
Key Terms to Review (18)
Agile: Agile is a project management and software development approach that emphasizes flexibility, collaboration, and customer satisfaction through iterative progress and continuous feedback. It connects teams and stakeholders in a way that promotes rapid adjustments to changing requirements, leading to a more efficient and adaptive process for delivering value. This approach encourages small, cross-functional teams to work in short cycles, known as sprints, allowing for regular assessment and improvement of both the product and the process.
Block Definition Diagram: A Block Definition Diagram (BDD) is a structural diagram in SysML that visualizes the system architecture by illustrating the system's blocks and their relationships. It helps in defining the components, attributes, and operations of a system while capturing both functional and physical decompositions.
Enterprise Architect: An enterprise architect is a professional responsible for aligning an organization's IT strategy with its business goals, ensuring that the architecture of systems and technologies supports these objectives. They play a crucial role in capturing requirements, defining system architecture, and managing the integration of various components across complex systems.
Functional Requirements: Functional requirements define the specific behaviors, functions, and capabilities a system must possess to fulfill its intended purpose. These requirements serve as a foundation for understanding user needs and expectations, guiding the design and implementation of systems while ensuring that the final product meets both stakeholder needs and operational criteria.
INCOSE Framework: The INCOSE Framework is a structured approach to systems engineering that provides guidelines and best practices for developing complex systems throughout their lifecycle. This framework emphasizes the importance of defining system architecture using models, which helps in visualizing, analyzing, and verifying system requirements and performance. By integrating various modeling techniques, the framework facilitates effective communication among stakeholders and ensures that system components work harmoniously.
Interfaces: Interfaces are defined as points of interaction between different system components, allowing them to communicate and work together effectively. In the context of systems engineering, they are critical for ensuring that subsystems can integrate seamlessly, providing a clear understanding of the data exchanged and the functions performed at these interaction points.
Internal Block Diagram: An Internal Block Diagram (IBD) is a SysML representation that shows the internal structure of a block, including its parts and their connections. This diagram is essential for visualizing how components interact and collaborate to fulfill the block's responsibilities, making it crucial for defining system architecture using models, understanding the relationships between different components, and representing their behavior and interfaces.
MagicDraw: MagicDraw is a powerful modeling tool used for visualizing, analyzing, and designing systems using various modeling languages such as SysML and UML. It supports model-based systems engineering (MBSE) by enabling users to define system architecture, capture requirements, and perform simulations effectively, making it essential for industries like aerospace, automotive, and defense.
Model validation: Model validation is the process of ensuring that a model accurately represents the real-world system it is intended to simulate or predict. It involves verifying that the model meets its requirements and is capable of producing reliable and accurate outputs based on given inputs. This process is crucial as it connects the requirements captured, the architecture defined, and the configurations managed to ensure that models are sound and dependable across various industries.
Model Verification: Model verification is the process of ensuring that a model accurately represents the intended system's specifications and requirements. This process is crucial in various engineering disciplines as it confirms that the model behaves correctly and adheres to predefined rules, providing confidence that it can effectively support decision-making and system development.
Requirements Elicitation: Requirements elicitation is the process of gathering and understanding the needs and expectations of stakeholders regarding a system or product. This involves various techniques to discover, analyze, and document what users require, ensuring that the final system aligns with their needs. It plays a vital role in shaping how requirements are captured, managed, and ultimately influences the system architecture and interface definitions.
Requirements Traceability: Requirements traceability is the ability to link and track the relationships between requirements, their origins, and their fulfillment throughout the lifecycle of a system. This ensures that all requirements are accounted for, changes are managed effectively, and validation and verification processes can be conducted efficiently.
Stakeholder Needs: Stakeholder needs refer to the requirements and expectations of individuals or groups who have an interest in the outcome of a project or system. Understanding these needs is essential because they guide the development process, ensuring that the final product meets the desires and concerns of all parties involved, from users to investors and regulatory bodies. By capturing and analyzing stakeholder needs, teams can create a clear framework for decision-making and prioritization throughout the system architecture definition.
SysML: SysML, or Systems Modeling Language, is a general-purpose modeling language used in systems engineering to create visual models of complex systems. It provides a standardized way to represent system requirements, behaviors, structures, and interactions, making it easier to communicate and analyze system designs across various stakeholders.
System Hierarchy: System hierarchy refers to the arrangement of a system into levels of subsystems or components, where each level represents a different layer of complexity and functionality. This structure helps in organizing system elements in a way that clarifies relationships and dependencies, facilitating better understanding, design, and management of the system as a whole.
UML: Unified Modeling Language (UML) is a standardized modeling language used to visualize, specify, construct, and document the artifacts of a software system. It provides a way to represent the design of systems through various types of diagrams, making it essential for capturing and managing requirements, defining architectures, and facilitating communication among stakeholders.
V-Model: The V-Model is a systems development lifecycle model that emphasizes the relationship between the development phases and the corresponding testing phases, represented in a 'V' shape. This model highlights the importance of validation and verification processes at every stage of development, ensuring that requirements are met through systematic testing as each aspect of the system is built.
Zachman Framework: The Zachman Framework is a structured way of viewing and defining an enterprise architecture, using a grid that categorizes various aspects of an organization’s architecture across different perspectives. It emphasizes the importance of understanding both the details and the broader context in which a system operates, providing a comprehensive blueprint that aids in system design and development. By organizing architectural artifacts into a matrix, it supports better communication and alignment among stakeholders.