API Operations

(Section: Operations and Management)

1) Purpose and principles

The API is the ecosystem's "operational layer": anything not automated through a contract turns into manual work and risk.

• Contract-first: first specification (OpenAPI/JSON Schema/AsyncAPI), then implementation.
• Secure-by-default: minimal scopes, short TTL, mutual-TLS/signatures.
• Observable: end-to-end tracing and SLA metrics.
• Idempotent: Replay safe.
• Backwards-compatible: evolution without "breaking" changes.
• Auditable: cryptographically confirmed facts (receipts).

2) Contract and models (reference)

OpenAPI for sync requests; AsyncAPI for events/webhooks.
Required fields in each resource are 'id', 'version', 'created _ at', 'updated _ at', 'tenant', 'region', 'trace _ id'.

Example of a contract fragment

yaml paths:
/payments/payouts:
post:
operationId: createPayout requestBody:
content:
application/json:
schema:
$ref: '#/components/schemas/PayoutRequest'
responses:
"202": { $ref: '#/components/responses/AcceptedWithReceipt' }
headers:
Idempotency-Key:
schema: { type: string }
required: true components:
responses:
AcceptedWithReceipt:
description: Accepted, processing asynchronously headers:
Receipt-Hash: { schema: { type: string } }

3) Authentication, authorization, scopes

OAuth2/OIDC for users/partners client-credentials/JWT для S2S.
Scopes/resource roles: 'payments. write`, `catalog. read`, `audit. export`.
ReBAC: access "by ownership" (tenant/account/sub-account).
JIT secrets: short-lived tokens, device/subnet/region binding.
Device posture & mTLS for critical operations (payments, keys).

4) Idempotence and "exactly once"

Idempotency-Key (header) + dedup by '(key, account, route)' on the TTL window.
Outbox/CDC to post events - guaranteed delivery.
Exactly-once-effects: side effects are captured through a transaction journal; repetition leads to the same "receipt" ('receipt _ hash').
Retry policies: exponential back-off, jitter, maximum windows.

5) Limits, quotas, prioritization

Rate limits: per-key/tenant/route/region; "soft" (429) and "hard" (cutoff).
Quotas/budgets: monthly/daily caps, webhooks' QuotaCapReached '.
Fair-use: priority of tenants by service level (Gold/Silver/Bronze).
Burst buffers: short bursts without degradation of neighbors.

6) Pagination, filters, samples

Cursor-based (stable ordering по `created_at,id`), `page_size` ≤ 1000.
Time-sliced samples ('from', 'to', 'watermark') for logs/transactions.
Filtering DSL: whitelisted поля, `?status=...&tenant=...&region=...`.
Consistency hints: 'snapshot _ at '/' as _ of' for reporting APIs.

7) Versioning and compatibility

SemVer: `v1`, `v1. 1 '(extensions),' v2 '- only on new paths/namespaces.
Evolution rules: only add fields/values, "deprecate → remove" through the window.
Compatibility tests: "contracts-as-tests" (consumer-driven).

8) Events, webhooks and receipts

AsyncAPI describes the themes/payload/signatures.

Caption: HMAC/EdDSA, headers' X-Signature ',' X-Nonce ',' X-Timestamp '(narrow window)

Receipts: 'receipt _ hash' and DSSE signature on critical events (payments, RTP/limit changes, price lists).
Retrai and dedup: idempotency according to 'idempotency _ key '/' event _ id'.
DLQ/quarantine: invalid/repeated reports with causes.

9) Observability and quality

Traces: mandatory 'trace _ id/span _ id' through gateway/business events/webhooks.
Metrics: availability, p50/p95/p99, error-rate, retry-rate, cost per 1k.
Logs: structured, no secrets/PII; 'tenant/region/version'labels.
SLO/alerts: SLO-oriented conditions and auto-runes (pause/re-route/rollback).

10) Errors and status semantics

2xx - success (202 for asynchronous operations).
4xx - client's fault (422 - validation, 409 - conflict/idempotency, 429 - limits).
5xx - temporary problems.
Error body: 'code', 'message', 'trace _ id', 'hint', 'retry _ after?'.
UX for partners: a table of "what to do" for each error.

11) Policies-as-code (OPA/ABAC)

Centralized authorization: "who/what/where/when/why."

Policies in Git, code review, CI tests (pre-flight: "will the policy allow? »).

SoD check: "create payment" ≠ "approve."

12) Security, privacy, compliance

PII minimization: tokenization/masks, access to the primary only through approved jabs.
Secrets: Vault/KMS, short TTL, rotations; prohibition of shared secrets.
Encryption: mTLS/TLS 1. 3, AES-GCM at-rest, HSTS/PKP where appropriate.
Jurisdiction-aware - Localization of data/keys per region.
Audit logs: WORM, Merkle-slices, DSSE-signatures.

13) Operation: SLI/SLO and dashboards

• Availability per-route/region.
• p95 latency (read/write).
• Success of webhooks (receipts), delivery lag.
• Error-rate/Retry-rate.
• Cost per 1k requests and egress.

SLO (example): 99. 95% availability; p95 ≤ 120/250 ms; webhooks ≥ 99. 5 %/5-min; P1 MTTR ≤ 60 min.

14) Change Management (Releases/Rollbacks)

Blue-Green/Canary for gateways and critical routes.
Ficheflags for no-release behavior.
Expand→Migrate→Contract for schemas and payload.
Руны: Rollback Release, Disable Flag, Re-route, Flush Cache.
Artifacts: signed images/manifests, version registry.

15) SDK, clients, sandboxes

Official SDKs (TS/Java/Python/Go) with the same error and retray semantics.
Sandbox environments with test keys/certificates and PSP/KYC/content provider simulators.
Contract-tests are included in the CI SDK, nightly compatibility.

16) Data model (simplified)

`api_key` `{id, tenant, scopes[], ttl, created_by}`

`rate_plan` `{tenant, quotas{route→cap}, burst, priority}`

`request_log` `{trace_id, route, actor, idempotency_key?, status, latency_ms, region, cost_unit}`

`webhook_receipt` `{event_id, endpoint, status, attempts, receipt_hash, signature}`

`policy` `{version, rules, signer, dsse}`

17) RACI

18) Quality metrics

Contract Drift: 0 "breaking" changes without deprecate.
Idempotency Error Rate: ≤ 0. 01%.
Webhook Success: ≥ 99. 5%, lag p95 ≤ 60 s.
Auth Fail vs Abuse: share of malicious blocks, noise ≤ target level.
Cost/1k: control by routes and regions (budgets/cap-alerts).
Adoption SDK: share of traffic through official SDKs.

19) Incident playbooks

Spike 429/limits: raise cap for Gold, throttling "noisy" keys, connection with a partner.
WebhookLag: increase workers/batches, prioritize queues, temporarily turn off optional webhooks.
PriceMismatch (catalog/FX/Tax): version reconciliation, cache force disability, artifact rollback, compensation.
PSP Outage: route switching, quarantine of "gray" transactions, replay.
Compromise API-key: immediate recall, rotation, audit of the last 30 days.

20) Specificity of iGaming/fintech

RTP/Limits API: only aggregates and profile versions; changes - with receipts.
Payments/payouts: 202 + signed webhooks; order key idempotency.
Affiliates: conversion dedup, escrow for disputes, signed reports.
Responsible play: Expose "guardrails API" for limits and RG events.

21) Implementation checklist

• Described contract (OpenAPI/AsyncAPI), CI validation and consumer-tests.
• Configured OAuth2/OIDC, scopes, JIT secrets and mTLS for critical routes.
• Idempotency, retrai, DLQ and quarantine introduced.
• Caps/Quotas/Priorities and Alerts.
• Cursor pagination, 'as _ of' consistent samples.
• Versioning and Deprecation Policy.
• Webhooks with signatures/receipts, replay and dedup.
• Trace/metrics/logs, SLO and runes.
• WORM logs, DSSE signatures, Merkle slices.
• SDK, sandbox, simulators, code samples and how-to.

22) FAQ

Why 202 for long operations?
In order not to hold the connection and provide a reliable retray/receipt via webhook.

Do you need both OpenAPI and AsyncAPI?
Yes: sync for commands/requests, async for events/state negotiation.

How to avoid breaking changes?
Add-only rule, deprecate → observe → remove, customer test contract.

Where to store receipts?
In a WORM zone with signatures; 'receipt _ hash' is returned to the client and checked upon request.

Summary: Operations via API are the discipline of contract and operation: strict access model and idempotency, limits and versions, observability and SLO, signatures and receipts. Add sandboxes and SDKs - and partners will integrate quickly, securely and predictably, and businesses will scale without loss of quality or compliance.