Understanding the Arcadia method: principles and practices

Essay by Dumkin Nikita (nadumkin@edu.hse.ru)

In contemporary software and systems engineering, the complexity of system architecture demands robust methods that facilitate comprehensive analysis and design. The ARChitecture Analysis and Design Integrated Approach (ARCADIA) method has emerged as a significant tool for systems architects, offering an integrated framework that encompasses both system analysis and design. By establishing a coherent approach to model-driven engineering, ARCADIA helps manage the intricacies involved in systems architecture, ensuring alignment with stakeholder requirements and enhancing system understanding. This essay will delve into the essence of the ARCADIA method, elucidate its fundamental principles, explore its practical usage, highlight best practices, and conclude with its implications in the broader field of systems engineering.

The ARCADIA method is a model-driven approach developed by Thales Group, designed to simplify the architecture of complex systems. It directly focuses on the architectural phases of system development, leveraging graphical models to enhance communication among stakeholders. The method supports the entire system lifecycle, from early conceptual design through to implementation, verification, and validation. ARCADIA facilitates the representation of various system aspects, such as functional behavior, structural design, and quality attributes, by employing specific modeling languages like SysML (Systems Modeling Language) and UML (Unified Modeling Language). Its comprehensive nature allows architects and engineers to analyze trade-offs and make informed decisions, thereby producing systems that meet the intricacies of both operational environment and user expectations.

The ARCADIA method provides different working levels: Operational analysis, Analysis of the system needs, Logical architecture, Physical architecture and End product breakdown structure (EPBS). Description of each level can be found below. Important notion is that the method does not prescribe mandatory to be top-down, if for example ACRCADIA is applied to existing system it is also possible to be bottom-up.

Fig 1. Main levels of ARCADIA

Operational analysis The goal of operational analysis is to identify the needs and objectives of future users of the system to provide compliance between expectations and final result. If simplified, this level is a model representation of users' jobs. It proposes concepts: Operational capability, Operational entity, Operational actor, Operational activity, Operational interaction, Operational process and Operational Scenario.

Fig 2. Operational analysis

System analysis System analysis is an answer for the question “What the system must accomplish for the users?”. This level describes systems capabilities and functions that should cater to the operational needs. System analysis impies external functional analysis to declare required system functions according to non-functional requirements. At this level the system is represented as black box that involves only allocated functions. It proposes concepts: System, Actor, System capability, Function, Functional exchange, Component exchange, Scenario and Functional chain.

Fig 3. System analysis

Logical architecture The objective of logical architecture is to identify logical components inside the system. This level is used for finding the way where the system will fulfill the expectations. The difference with the previous level is that logical architecture is about internal functional analysis. Logical architecture is based on the system analysis, subfunctions carrying out the system functions and their splitting into logical components. Logical architecture proposes concepts: Logical component, logical actor, Logical function, Functional exchange, component exchange, Logical scenario and Functional chain.

Fig 4. Logical architecture

Physical architecture The goal of physical architecture is to define the final architecture of the system in perspective how it would be built. This level adds required for implementation functions, technical choices and two types of physical components: Behavior Physical Component and Node Physical Component. It proposes similar concepts and some additional: Physical port, Physical link and Physical path.

Fig 5. Physical architecture

EPBS End product breakdown structure defines what is expected from the provider of each component. The goal of this level is to find out and declare conditions that each component must satisfy based on the physical architecture. To ease management of responsibilities physical components are grouped into configuration items. The main concept is Configuration item, which can be divided into System-type configuration item, Prime configuration item, Computer software configuration item, hardware configuration item, Non-developed configuration item and Component off the shelf.

Fig 6. End product breakdown structure

The ARCADIA method provides a large number of different types of diagrams to describe the system. List of main types of diagrams with examples can be found below.

Data Flow diagrams This type of diagrams is available at all levels. Data Flow diagram is representation of the information dependency network between functions.

Fig 7. Data Flow diagrams

Architecture diagrams The objective of Architecture diagram is to show allocation of functions to components.

Fig 8. Architecture diagram

Scenario diagrams This type of diagrams is very similar to the UML Sequence diagram, the main purpose is to represent messages between elements over time.

Fig 9. Scenario diagram

Mode and State diagrams Model and State diagram is representation of states linked together by transitions.

Fig 10. Mode and State diagram

Breakdown diagrams The goal of the Breakdown diagram is to show hierarchies of Logical components.

Fig 11. Breakdown diagram

Class diagrams Class diagram is very similar to UML Class diagram, it is also follow the same concepts Class Enumeration, Type, Property, etc. But it’s also has specific concepts, for example Exchange items.

Fig 12. Class diagram

Capability diagrams Capability diagram represents relations between Missions, Capabilities and Actors. This type of diagrams is useful for Operational analysis and System analysis.

Fig 13. Capability diagram

To use ARCADIA method is recommended to use Capella application. Capella is an Eclipse application that implements the ARCADIA method, offering a Domain Specific Modeling Language (DSML) and a dedicated toolset. One of its standout features is the embedded methodology browser, which guides users through ARCADIA principles and key activities, helping both beginners and experts create main diagrams systematically.

Going beyond traditional modeling tools, Capella verifies that model elements at different engineering levels correspond correctly. It organizes model checking rules, with architects able to customize validation profiles. Quick fixes offer immediate solutions when needed.

The ARChitecture Analysis and Design Integrated Approach (ARCADIA) method stands as a pivotal framework in the realm of systems engineering, providing a coherent structure for managing the complexities of modern system architectures. Its model-driven methodology, stakeholder-centric focus, and iterative development practices create a robust environment for architects and engineers navigating the nuances of architectural design. By applying ARCADIA principles and embracing best practices, organizations can enhance their capacity to deliver effective solutions that align with user requirements while adapting to the dynamic landscape of technology and innovation.

1. Pascal Roques, MBSE with the ARCADIA Method and the Capella Tool: https://hal.science/hal-01258014/
2. Pascal Roques, Systems Architecture Modeling with the Arcadia Method: https://books.google.ru/books?hl=ru&lr=&id=Qj3jCwAAQBAJ&oi=fnd&pg=PP1&dq=arcadia+method&ots=-3qDlRGlIt&sig=rBMMCSK9xIDNVlEOqL4NfoiMeYE&redir_esc=y#v=onepage&q=arcadia%20method&f=false
3. Jean-Luc Voirin, ARCADIA ENGINEERING LANDSCAPE: https://mbse-capella.org/resources/arcadia-reference/Arcadia%20Engineering%20Landscape.pdf
4. Jean-Luc Voirin, ARCADIA USER GUIDE: https://mbse-capella.org/resources/arcadia-reference/Arcadia%20User%20Guide.pdf
5. Jean-Luc Voirin, Model-based System and Architecture Engineering with the Arcadia Method: https://books.google.ru/books?hl=ru&lr=&id=R8jPCwAAQBAJ&oi=fnd&pg=PP1&dq=arcadia+method&ots=WZuNwW9tWq&sig=79Uq86iqVPCqivAQYOYd47zVjUE&redir_esc=y#v=onepage&q&f=false