generated: '2026-07-27'
method: searched
source: https://www.hydroone.com/saving-money-and-energy/green-button
note: >-
  Cross-cutting request/response semantics for Hydro One's Green Button surfaces.
  Hydro One publishes no endpoint reference, so every convention below is either
  stated in Hydro One's own third-party documentation and terms, or inherited
  from the NAESB REQ.21 ESPI standard that Ontario's Energy Data regulation binds
  the implementation to. Conventions that are neither published nor observed are
  recorded as unknown rather than guessed.
authentication:
  style: OAuth 2.0 authorization code (NAESB ESPI), customer-consented
  detail: authentication/hydro-one-authentication.yml
  transport: TLS required for all exchanges with HONI
  client_credentials: issued privately during onboarding; never published
  additional: RSA 2048-bit certificate exchange with a HONI-supported CA
authorization:
  model: ESPI function-block scopes
  syntax: 'FB=<block ids>;historyLength=<seconds>'
  detail: scopes/hydro-one-scopes.yml
  consent_holder: the Hydro One customer, who authenticates with Hydro One directly
  revocation: customer may revoke at any time; access is otherwise indefinite
payload:
  format: ESPI XML (Atom-based)
  media_type: application/atom+xml
  media_type_source: NAESB REQ.21 ESPI standard (not restated by Hydro One)
  json: false
  bulk_export: >-
    Download My Data provides up to 24 months of billing, consumption and
    transaction data as an XML file from inside My Account.
pagination:
  style: unknown
  note: >-
    ESPI resources are Atom feeds and the standard defines published/updated and
    interval query parameters, but Hydro One publishes no endpoint reference, so
    nothing is asserted about its implementation.
idempotency:
  supported: unknown
  note: >-
    No idempotency key, retry contract or replay semantics is documented. Connect
    My Data is read-only from the third party's perspective — the vendor retrieves
    customer data, it does not write to Hydro One. No `Idempotency` pointer is
    emitted.
rate_limiting:
  documented: false
  note: >-
    No published rate limits. The terms instead impose an obligation on the
    vendor: "incorporate industry standard controls into your Service that prevent
    a 'Denial of Service' type of attack."
errors:
  envelope: unknown
  problem_details_rfc9457: false
  note: No error catalogue or error reference is published.
versioning:
  detail: lifecycle/hydro-one-lifecycle.yml
  in_url: unknown
  note: ESPI resource paths conventionally carry the standard version (e.g. /espi/1_1/resource/...), but Hydro One's base URI is unpublished.
request_tracing:
  request_id_header: unknown
webhooks:
  supported: false
  note: >-
    No webhook, callback, event or streaming surface is documented. Connect My
    Data is a pull integration; no AsyncAPI artifact is emitted.
support:
  operational_contact: greenbutton@HydroOne.com
  contact_page: https://www.hydroone.com/contact
related:
- authentication/hydro-one-authentication.yml
- scopes/hydro-one-scopes.yml
- lifecycle/hydro-one-lifecycle.yml
- conformance/hydro-one-conformance.yml
- sandbox/hydro-one-sandbox.yml