commandresponse

Commandresponse is a communication pattern in computing in which a client sends a command or instruction to a system and the system returns a response containing results, status, or data. The pattern is widely used in interactive terminals, remote command execution, and many network protocols.

In a commandresponse model, the interaction is typically synchronous: the client waits for the server’s reply before issuing another command. The reply usually includes a status code or indicator and any requested data. Some implementations include error handling in the response; others use separate error fields or codes. The mechanism can be text-based (lines of output) or binary (structured messages).

Common contexts include command-line interfaces, remote procedure call frameworks, and network protocols like SSH, SMTP, or FTP, where clients send commands and servers respond with codes and data. Modern APIs also reflect command-response semantics through HTTP request/response patterns, although these may be more accurately described as resource-oriented interactions with methods like GET or POST.

Design considerations include latency, timeouts, authentication and authorization, input validation, and idempotency. Stateless designs reprocess commands independently and generate responses; stateful designs may preserve context across commands via sessions. Security concerns include command injection and replay attacks; proper sanitization and encryption are essential.

See also: command-line interface, remote procedure call, request-response, protocol design.