XML vs JSON for Data Exchange

JSON: objects (maps), arrays, strings, numbers, booleans, null. No attributes; metadata lives as sibling keys. XML: elements, attributes, text nodes, namespaces, comments, processing instructions—richer document model suited to markup (HTML, SVG) and mixed content.

Converting XML with attributes to JSON often maps attributes to `@attribute` keys or nested `_attributes` objects depending on library—standardize one convention per pipeline.

XML tags repeat opening/closing names, inflating size versus JSON for equivalent data graphs. Streaming SAX parsers handle huge XML; JSON typically loads full tree in memory for simplicity unless using JSON lines streaming.

Mobile and browser clients prefer JSON payload size for latency. Batch mainframe XML files may prioritize schema validation over bytes on wire.

XSD enforces element order, attribute requirements, and complex types in XML ecosystems. JSON Schema validates JSON types and required keys with growing OpenAPI adoption for HTTP APIs.

When partners supply XSD, generate bindings or convert to JSON once at ingress with validation at boundary—do not silently drop mandatory attributes in mapping.

SOAP web services, HL7 healthcare messages, RSS/Atom feeds, and office document formats (DOCX internals) remain XML-heavy. Greenfield REST APIs almost default JSON.

Middleware converts XML↔JSON at gateway; maintain canonical internal format (usually JSON) to reduce dual code paths in application logic.

Handle repeated elements: XML allows duplicate sibling tags; JSON arrays must represent them explicitly. Single-child vs array ambiguity breaks naive converters—use rules for always-array paths.

Test round-trip on representative payloads including namespaces, CDATA sections, and empty elements. Human-readable xml-to-json in browser helps debug partner payloads before automating.