specification: API Commons Rate Limits
specificationVersion: '0.1'
schema: https://raw.githubusercontent.com/api-evangelist/interface-research/main/schema/api-commons.yml#/$defs/RateLimits
provider: Hong Kong University of Science and Technology
providerId: hkust
created: '2026-06-03'
modified: '2026-08-30'
generated: '2026-08-30'
method: probed
reconciled: false
tags:
  - University
  - Higher Education
  - Education
  - Rate Limiting
description: >-
  HKUST publishes no numeric rate limit for any of its API surfaces. It does state a
  throttling POSTURE for the one surface that has an enforcement point: the ITSO service page
  says the HKUST API Gateway "will control access to APIs according to pre-defined access
  frequency, intensity, etc. and prevent overloading", and that protecting the underlying
  systems of record from application traffic is the reason the gateway exists at all. The
  thresholds themselves are not published, and the gateway cannot be exercised without an
  approved subscription key, so they could not be measured.
notes: >-
  Corrected 2026-08-30. The previous version of this file described throttling on OAI-PMH and
  IIIF endpoints; neither exists here. The DataSpace@HKUST OAI-PMH provider is switched off
  and returns 503, and no IIIF surface was found on any HKUST host.
sources:
  - https://itso.hkust.edu.hk/services/it-infrastructure/api-gateway-api-portal
  - https://pathadvisor.ust.hk/api/floors
responseCodes:
  throttled: 429
  observed: none
limits:
  - name: HKUST API Gateway
    surface: https://hkust.azure-api.net
    x-operator: tenant
    scope: subscription-key
    metric: unpublished
    limit: not published
    notes: >-
      Azure API Management enforces per-subscription throttling policies. HKUST states that
      the gateway limits access frequency and intensity but publishes no figures, and the
      policies are not visible without an approved key.
  - name: HKUST Path Advisor API
    surface: https://pathadvisor.ust.hk/api
    x-operator: institution
    scope: none
    metric: none
    limit: none published
    notes: >-
      No rate-limit headers of any kind are returned, and no 429 was observed during probing
      on 2026-08-30. Absence of a stated limit is not permission for volume: this is a campus
      service on university infrastructure. Responses do carry a weak ETag, so conditional
      requests are the correct way to reduce load.
  - name: DataSpace@HKUST
    surface: https://dataspace.hkust.edu.hk/api
    x-operator: institution
    scope: unpublished
    metric: unpublished
    limit: not published
    notes: >-
      No rate-limit documentation published by HKUST; upstream Dataverse defaults apply.
policies:
  - name: Backoff Strategy
    description: Exponential backoff with jitter; honor Retry-After if it ever appears; back off on any 5xx.
  - name: Conditional Requests
    description: >-
      Cache the small reference collections on the Path Advisor API (/buildings, /floors,
      /tags) and revalidate with If-None-Match against the returned ETag.
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com