---
aid: caltech
name: California Institute of Technology — Error Semantics
generated: '2026-08-19'
method: probed
description: >-
  Error behaviour observed by deliberately malforming requests against Caltech-operated
  surfaces on 2026-08-19. Every entry below is a response actually received.
source:
  - https://data.caltech.edu/api/records/zzzzz-zzzzz
  - https://data.caltech.edu/oai2d?verb=Bogus
  - https://service.scedc.caltech.edu/fdsnws/event/1/query?starttime=NOTADATE&format=text
  - https://ned.ipac.caltech.edu/tap/sync

surfaces:
  - surface: CaltechDATA REST API
    x-operator: institution
    content_type: application/json
    machine_readable: true
    shape:
      status: integer
      message: string
    observed:
      - request: GET https://data.caltech.edu/api/records/zzzzz-zzzzz
        status: 404
        body: '{"status": 404, "message": "The persistent identifier does not exist."}'
    assessment: >-
      Structured JSON error with a numeric status and a human-readable message. No error
      code vocabulary, no problem+json (RFC 9457), no documentation link in the body.

  - surface: CaltechDATA / CaltechAUTHORS OAI-PMH
    x-operator: institution
    content_type: text/xml
    machine_readable: true
    shape:
      element: 'OAI-PMH/error[@code]'
    observed:
      - request: GET https://data.caltech.edu/oai2d?verb=Bogus
        status: 200
        body: '<error code="badArgument">This is not a valid OAI-PMH verb:Bogus</error>'
    assessment: >-
      Spec-conformant OAI-PMH error codes. Note the protocol returns HTTP 200 with an
      error element in the body — correct per OAI-PMH, but it means HTTP status alone is
      not a success signal on this surface.

  - surface: SCEDC FDSN Web Services
    x-operator: institution
    content_type: text/plain
    machine_readable: partial
    observed:
      - request: GET /fdsnws/event/1/query?starttime=NOTADATE&format=text
        status: 400
        body: |
          Error 400: doIrisProcessing - Bad date value for starttime: NOTADATE
          Request: ...
          Request Submitted: 2026/08/19 21:08:19 UTC
          Service version: Service: fdsnws-event  version: 1.1.1
      - request: GET /fdsnws/dataselect/1/query (window with no data)
        status: 204
        body: ''
    assessment: >-
      FDSN-standard behaviour: 204 for an empty result set rather than an empty 200, and
      400 for a malformed parameter. The 400 body is plain text — parseable by convention
      but not a structured error document. It usefully echoes the submitted request, a
      timestamp and the service version, which makes failures reproducible.

  - surface: IVOA TAP services (IRSA, NED, NASA Exoplanet Archive)
    x-operator: institution
    content_type: application/xml (VOTable)
    machine_readable: true
    observed:
      - request: GET https://ned.ipac.caltech.edu/tap/sync (missing REQUEST parameter)
        status: 400
        body_elements:
          QUERY_STATUS: 'ERROR — The parameter "request" must be provided and its value must be equal to "doQuery" or "getCapabilities"!'
          PROVIDER: 'NASA/IPAC Extragalactic Database (NED)'
          REQ_ID: S1787173473711
          ERROR_TYPE: fatal
          ACTION: sync
    assessment: >-
      The strongest error semantics in Caltech's estate. VOTable INFO elements carry a
      machine-readable QUERY_STATUS, an error severity, the provider identity and a
      request id suitable for support correlation — all per the IVOA DALI specification.

gaps:
  - No RFC 9457 problem+json anywhere in the estate.
  - No published error-code reference for any surface.
  - No documented retry or backoff guidance.
  - Error shape differs per surface (JSON, OAI-PMH XML, plain text, VOTable), which is
    expected given four independent operators inside one institution but means no single
    client contract covers Caltech.