HTTP

Overview

HTTP is an application-layer, request-response protocol used by clients, servers, and intermediaries to exchange representations and control information on the web. HTTP is an application-layer messaging protocol; it transports requests and responses but does not define a payment API’s domain objects, permissions, or state transitions. HTTP is stateless at the protocol level, although applications add sessions through cookies, tokens, or other identifiers. Intermediaries can transform or cache traffic according to protocol rules and configuration. HTTP alone does not provide encryption; HTTPS combines HTTP with TLS. The HTTP contract should define identifiers, validation, authorization, status semantics, errors, limits, and version behavior at the same boundary.

For HTTP, developers should retain one correlation path across these stages because an immediate response can differ from later provider, blockchain, payment, accounting, or settlement state. Hypertext Transfer Protocol defines methods, targets, headers, status codes, and message semantics for communication between user agents and servers. Methods such as GET, POST, and DELETE express intent, while response status codes describe request outcomes. Secure applications still need authentication, authorization, validation, origin protections, safe caching, and bounded message sizes. It supports websites, APIs, media delivery, proxies, caches, and many machine-to-machine integrations. A successful transport result from HTTP should not be interpreted beyond the exact API state documented by the provider.

Changes to HTTP should be checked against older clients, stored payloads, enum growth, default behavior, and retry assumptions.

Observability for HTTP should record operation, version, principal, request ID, latency, retry count, error code, and final state without exposing secrets.