The lost art of XML

Original Article ↗ Hacker News Discussion ↗

Why XML Declined

  • Several commenters argue XML lost mainly due to complexity, awkward tooling, and poor developer experience, not bandwidth.
  • Verbosity was a frequent complaint, though with compression the on‑wire size was often similar to JSON; CPU and memory costs (especially on early mobile) and parsing complexity were more significant.
  • Attributes, namespaces, entities, CDATA, mixed content, and multiple modeling choices made simple data tasks painful and error‑prone.
  • The broader XML ecosystem (SOAP, WS-*, WSDL, complex schemas) became synonymous with over‑engineering and fragile integrations.

JSON’s Appeal and Limitations

  • JSON maps directly to ubiquitous data structures (maps and arrays) and matched the mental model of dynamic languages (JS, Python, PHP, Ruby).
  • Early JSON could be parsed in browsers with minimal tooling, which massively boosted adoption and improved developer experience.
  • JSON is criticized as “lobotomized”: no comments, weak typing, external schema standards, and fewer formal guarantees. However, its simplicity is viewed as a feature that avoids many XML footguns.
  • Some note we are gradually recreating XML‑like tooling around JSON (schemas, JSONPath, transformation tools).

XML’s Original Purpose and Strengths

  • Multiple comments stress XML was designed as a document/markup format, not initially as a data serialization format; data‑exchange use was layered on later.
  • XML shines for human‑authored, tree‑structured documents, configuration with comments, and domains needing strict validation and rich semantics.
  • Tooling like XSD, XSLT, XPath, and XQuery is remembered as powerful, especially for contracts and transformations, though often hard to learn.

Schemas, Namespaces, and Validation

  • Schemas are seen as both a killer feature and a major source of pain: XSD is widely called incomprehensible; RELAX NG praised but niche.
  • Namespaces divide opinion: some found them invaluable in large systems, others call them a “hell” that complicates every operation.
  • Strong schema‑validated XML is still favored in complex B2B/banking and enterprise scenarios where 1:1 type systems and precise contracts matter.

REST, RPC, and Ecosystem Shifts

  • Discussion notes that most so‑called REST APIs are really RPC over HTTP with JSON.
  • Some argue industry abandoned true REST and XML, then spent years reinventing schema/documentation layers on top of JSON RPC (OpenAPI, similar efforts).
  • Others maintain that for most web dev—small, internal, fast‑changing services—simple JSON APIs are entirely adequate.

Ongoing Niche Uses and Alternatives

  • XML remains in office document formats, some configuration setups, financial and banking interfaces, and XQuery‑based systems.
  • Many prefer binary or other typed formats (Protocol Buffers, ASN.1/DER, custom schemes) for machine‑to‑machine communication.
  • Several commenters think XML’s decline was justified; a minority argue we threw away a solid core technology because of fashion and bad ecosystems.