In systems analysis and design, what do we call the channel or mechanism that enables communication across the boundary between two or more subsystems so they can exchange data and requests in a controlled way?

Introduction / Context:
An information system is often partitioned into subsystems, each responsible for a well-defined set of functions. For these subsystems to collaborate, they must communicate across clearly defined boundaries. The concept that formalizes this collaboration is the interface, which specifies how data, control signals, and service requests are exchanged.

Given Data / Assumptions:

• Multiple subsystems need to coordinate work and exchange information.
• Communication must occur across subsystem boundaries.
• We are looking for the standard systems-analysis term for this channel or mechanism.

Concept / Approach:
An interface defines the contract between subsystems: what operations are available, what inputs are expected, what outputs are returned, allowed data formats, error codes, and constraints. Interfaces may be API calls, message schemas, file layouts, or user-operated handoffs. Good interface design promotes low coupling and high cohesion, enabling independent evolution of subsystems while preserving interoperability.

Step-by-Step Solution:
1) Identify that subsystems communicate across a boundary.2) Recognize that a formal contract is required to avoid ambiguity and tight coupling.3) Name this contract/mechanism: the interface.4) Note that interfaces may be synchronous (function calls) or asynchronous (messages, events).5) Conclude that standardized interfaces reduce integration risk and ease maintenance.

Verification / Alternative check:
Software architecture methods (layered, service-oriented, microservices) uniformly rely on explicit interface definitions—e.g., REST endpoints, queues, or RPC signatures—to govern cross-boundary communication.

Why Other Options Are Wrong:
Actigram: not a standard term in SDLC communication.Walkthrough: a review technique, not a communication channel.Data path: a hardware/low-level term; lacks the contractual semantics of an interface.None of the above: incorrect because “Interface” fits exactly.

Common Pitfalls:
Confusing physical connectivity with logical contracts; omitting error handling and versioning in interface definitions; allowing undocumented side effects.

Final Answer:
Interface