generated: '2026-07-23'
method: searched
source: https://openbankinguk.github.io/read-write-api-site3/
standard: OBIE Read/Write API Standard (UK Open Banking) + FAPI 1.0 Advanced
notes: >-
  Cross-cutting request/response semantics for Nationwide's OBIE-conformant APIs.
  The Read/Write conventions are defined by the UK Open Banking standard that
  Nationwide implements; the Open Data conventions are the OBIE Open Data profile.
authentication:
  open_data: none (public)
  read_write: OAuth2 authorization_code + client_credentials, OIDC, mutual-TLS
  see: authentication/nationwide-building-society-authentication.yml
idempotency:
  supported: true
  scope: Payment Initiation (PIS) and VRP write operations
  header: x-idempotency-key
  max_length: 40
  retention: 24 hours
  semantics: >-
    Each request is processed only once per x-idempotency-key value within the
    24-hour window; a replay with the same key and identical payload returns the
    original result rather than creating a duplicate payment. Standard OBIE
    Read/Write behaviour that Nationwide implements.
request_tracing:
  header: x-fapi-interaction-id
  format: RFC 4122 UUID
  semantics: >-
    Client sends a unique UUID per request; the server echoes it back (or mints
    one) in the response header for end-to-end interaction tracing.
  related_headers:
  - name: x-fapi-auth-date
    note: Time the PSU last logged in (RFC 7231 date), on AIS calls.
  - name: x-fapi-customer-ip-address
    note: PSU IP address when the request is PSU-present.
  - name: x-customer-user-agent
    note: PSU-facing client user agent.
message_signing:
  header: x-jws-signature
  note: Detached JWS signature on payment/consent write requests and responses.
pagination:
  style: cursor-links
  response_field: Links (Self, First, Prev, Next, Last)
  meta_field: Meta.TotalPages
  note: OBIE Read/Write collections page via Links/Meta; page size negotiated by the ASPSP.
conditional_requests:
  open_data:
    request_headers: [If-Modified-Since, If-None-Match]
    response_headers: [Last-Modified, ETag]
    note: OBIE Open Data supports HTTP conditional GET for cache validation (304 Not Modified).
versioning:
  scheme: uri-path
  open_data_current: v2.2 (Nationwide live host); OBIE Open Data spec v2.3/v2.4
  read_write_current: v3.1
  read_write_next: v4.0
  note: See lifecycle/nationwide-building-society-lifecycle.yml
error_envelope:
  format: OBErrorResponse1 (UK.OBIE.* error codes)
  media_type: application/json
  see: errors/nationwide-building-society-problem-types.yml
rate_limiting:
  signal: HTTP 429 Too Many Requests
  note: Per-TPP throttling applied by the ASPSP gateway; Open Data returns 429 under load.