The CPSA-FL framework emphasizes that architecture design must be driven by an understanding of both functional requirements and, crucially, quality attributes (non-functional requirements). These goals, such as performance, security, and modifiability, fundamentally shape the structural decisions. Starting with detailed class diagrams skips this essential analysis phase and risks building a structure that doesn’t meet the system’s critical goals.

The question is about a specific quality attribute (security) and how it is realized within a component’s internals and its interactions. A component-and-connector (C&C) view, potentially detailing security-specific components like encryption modules or access control connectors, is the standard architectural model for showing how runtime elements interact to achieve qualities like security, performance, or reliability.

An API Gateway is a fundamental architectural tactic for managing complexity at the system edge. Its primary purposes include request routing, API composition (aggregating responses from multiple services), and handling cross-cutting concerns (security, logging, rate limiting) in a centralized manner. While it may indirectly aid modularity, its direct purpose is to provide a unified interface and manage inter-service communication concerns.

The stakeholder’s question involves the sequence of interactions between components at runtime (the flow) and the system’s response to a fault (error handling). This describes dynamic behavior, which is distinct from the static structure shown in a layered diagram. Explaining this requires runtime models like sequence diagrams or state machines, and details of the chosen fault tolerance tactics (e.g., transactions, retries).

The team is analyzing and comparing architectural designs against specific quality attribute scenarios (in this case, a performance/scalability scenario: “Under increased load, response time remains below X and the system does not crash”). This is the core of architecture evaluation, where designs are assessed for their ability to meet requirements before significant resources are committed to building them.

In standard architectural terminology (e.g., as used in the CPSA syllabus), a “module” refers to a static unit of implementation (like a Java package, a C++ namespace, or a .NET assembly). Its concerns are development-time: how code is partitioned, responsibilities assigned, and dependencies managed to achieve qualities like maintainability and reusability. This contrasts with runtime concepts like components or executables.

The goal explicitly describes the ability to change one part of the system (the fraud detection service) with minimal impact on another, closely related part (the payment service), and to deploy that change independently. This is a classic description of modifiability, specifically supporting deployability as a sub-characteristic. The microservices style is often chosen to achieve this kind of independent lifecycle for teams and services.

Architectural decisions have a significant impact on the system’s structure, its quality attributes (like scalability, reliability, and performance), and constrain downstream implementation choices. Deciding on a state management strategy (distributed cache vs. server-local storage) is a major structural decision with wide-ranging consequences. The other options are low-level implementation details that do not shape the fundamental architecture.

The architect’s rationale is explicitly about fault tolerance and continued operation in the face of a dependency failure. By decoupling the services via asynchronous messaging, the failure of one does not immediately cause the failure of the other (the Order Service can queue messages). This is a direct application of the architectural tactic “design for fault tolerance” to improve system availability.

The CPSA-FL framework emphasizes that architecture design must be driven by an understanding of both functional requirements and, crucially, quality attributes (non-functional requirements). These goals, such as performance, security, and modifiability, fundamentally shape the structural decisions. Starting with detailed class diagrams skips this essential analysis phase and risks building a structure that doesn’t meet the system’s critical goals.0