Ecosystem API

(Section: Ecosystem and Network)

1) Goals and principles

• Fast, predictable integration (time-to-integration ↓).
• Reliability and scalability (SLO, QoS, backpressure).
• Safety and compliance (minimum rights, audit).
• Evolution without breakdowns (versions, compatibility, ficheflags).

Principles: contract-first, data minimization, idempotency, observability-by-default, "two speeds" of releases (core vs experimental).

2) API taxonomy

1. REST/HTTP - synchronous CRUD/command operations, idempotency-key, pagination/cursors.
2. gRPC/QUIC - low latency, streams, binary protocols.
3. Events (Pub/Sub) - domain events ('deposit.', 'payout.', 'bridge.', 'risk.').
4. Webhooks - reverse notifications with signatures and retrays.
5. GraphQL (limited) - aggregating reads over materialized storefronts.
6. Admin/Meta - directories, versions, statuses, keys, quotas.

Access levels: Public (limited methods/reading), Partner (scopes and quotas), Internal (private contours).

3) Contracts and schemes

OpenAPI/AsyncAPI/Protobuf IDL is a single source of truth.
Data Contracts - compatibility tests, circuit linters, prohibition of "breaking" fields without MAJOR.
Catalogs: assets/networks, PSP/methods, regions/jurisdictions, SDK versions, capability flags.

Minimum REST contract (OpenAPI fragment)

yaml openapi: 3. 0. 3 info: { title: Ecosystem Core API, version: "2. 6. 0" }
paths:
/v2/payouts:
post:
operationId: createPayout parameters:
- in: header name: Idempotency-Key required: true schema: { type: string, maxLength: 64 }
requestBody:
required: true content:
application/json:
schema:
$ref: "#/components/schemas/PayoutRequest"
responses:
"202": { $ref: "#/components/responses/Ack" }
"409": { description: "Duplicate (idempotent)" }
components:
schemas:
PayoutRequest:
type: object required: [amount, currency, destination]
properties:
amount:  { type: string, pattern: "^[0-9]+(\\.[0-9]{1,9})?$" }
currency: { type: string, example: "USD" }
destination: { type: string }
metadata: { type: object, additionalProperties: true }

Events (AsyncAPI)

yaml asyncapi: 2. 6. 0 info: { title: Ecosystem Events, version: "1. 9. 0" }
channels:
payout. finalized:
subscribe:
message:
name: PayoutFinalized payload:
type: object required: [id, ts, amount, currency, status, signature]
properties:
id: { type: string }
ts: { type: string, format: date-time }
amount: { type: string }
currency: { type: string }
status: { type: string, enum: ["finalized","failed"] }
signature: {type: string} # source signature

4) Versioning and compatibility

SemVer: `MAJOR. MINOR. PATCH`. MINOR/PATCH - backward-compatible; MAJOR - parallel versions ('/v1 ', '/v2') + adapters.
Rejection policy: window ≥ 90 days, "two lines" of support, automatic notifications for contracts.
Feature Flags: enable/disable fields/methods by region/partner.
Capability Negotiation: declaring supported profiles when shaking hands.

5) Idempotence, orders and cursors

Idempotency-Key for commands (create/cancel), TTL keys ≥ 72 hours.
Exactly-once semantics via outbox/inbox and idempotent consumer.
Pagination by cursors: 'next _ cursor', resistance to insertions/deletions.
Sorting and filters are stable, clearly documented.

6) Security and trust

mTLS (service↔service), pinning of serts and key rotation.
OAuth2/OIDC (client credentials, JWT with short TTL), PoP/DPoP for binding to the channel.
Webhook signatures (NMAS/key version/time), repetition protection.
RBAC/ABAC and PoLP: scopes, org_id/tenant_id, limits on object/operation.
DLP/PII minimization: PII prohibition in labels/logs, tokenization of identifiers.
Rate-limits and WAF: per org/route/region, abuse protection.

Sample Key Policy (YAML)

yaml auth:
oauth2:
issuer: "https://auth. ecosys"
jwks_uri: "https://auth. ecosys/.well-known/jwks. json"
token_ttl_s: 900 mtls:
required_for: ["internal","partner_p0"]
scopes:
- name: payouts:write
- name: payouts:read
- name: events:subscribe

7) Quotas, QoS and backpressure

QoS classes: P0 (payments/bridge/finalization), P1 (product), P2 (bulk/archive).
Quotas/limits: RPS, concur-requests, bytes/sec, subject/party for events.
Admission control: early rejection of "expensive" requests, heavy-query-guard.
Backpressure: tokens/credits, queues with DLQ, retrays with jitter.

Quota Policy

yaml quotas:
partner_default:
rps: 200 concurrent: 100 webhooks_outbound_rps: 50 p0:
rps: 100 p95_latency_ms: 400

8) Observability: SLI/SLO, metrics, traces

• p95/99 latency по маршрутам, Success Rate, Error budget burn, Queue-lag p95, Freshness webhooks, Delivery success%.
• Contract Compliance% (schemas/signatures).
• Webhook retry/dropped%.

SLO: P0 p95 ≤ 400 ms, Availability ≥ 99. 95%; Webhook delivery p95 ≤ 2 с; Events freshness p95 ≤ 60 с.

Metrics: latency histograms, error codes, size of responses, RPS, per-tenant.
Traces: end-to-end 'trace _ id' (edge→gateway→service→DB→event/webhook).
Logs: structured, without PII, correlation by 'request _ id'.

9) Downtime-free release patterns

Blue-Green/Canary with SLO gates and outlier-ejection.
Schema-first evolution: only adding fields, adapters for old clients.
Zero-downtime database migrations: online DDL, bidirectional converters.
Change control: timelock, audit and compatibility registry.

10) Catalogues and registers

API/Version Register

sql
CREATE TABLE api_registry(
name TEXT, kind TEXT,      -- rest    grpc    events    webhook version TEXT, status TEXT,   -- active    canary    deprecated    retired slo JSONB, owner TEXT,
PRIMARY KEY (name, version)
);

Event Catalog

sql
CREATE TABLE event_catalog(
topic TEXT PRIMARY KEY,
schema_version TEXT,
qos TEXT,
retention_days INT,
pii BOOLEAN DEFAULT false
);

Keys/scopes

sql
CREATE TABLE api_keys(
key_id TEXT PRIMARY KEY,
org_id TEXT, scopes TEXT[], status TEXT, expires_at TIMESTAMPTZ
);

11) Testing and compliance with contracts

Contract-tests: client generation, schema validation, negative-_cases.
Replay event tests: resistance to repetition/reordering.
Chaos/Lat-tests: loss/jitter injections, slow stor.
Security-tests: webhook signatures, key rotation, replay attacks.
Performance profiles: SLA spikes, hot routes, DA/dependency bridge.

12) Examples of interfaces

Webhooks (signature and retrai)

yaml webhooks:
deliveries:
retry:
attempts: 5 backoff_ms: [200, 800, 1600, 3200, 6400]
jitter: true signature:
alg: "HMAC-SHA256"
header: "X-ECO-Signature"
timestamp_header: "X-ECO-Timestamp"
tolerance_s: 300

GraphQL (Aggregating Reads, Read Only)

graphql type Query {
payouts(status: [Status!], first: Int!, after: String): PayoutConnection!
}

gRPC (event flow)

proto service EventStream {
rpc Subscribe(SubscribeRequest) returns (stream Event);
}

13) Processes and roles

API Owner - Contract/Version/SLO/Quota.
Security - keys/signatures/audit/DLP.
SRE/Ops - dashboards, alerts, capacity.
Partner Success - onboarding, limits, phicheflags.
Compliance - jurisdictions, sanctions, reporting.

14) Dashboards

Core API: latency/error/RPS by route and tent.
Webhooks: delivery p95, retries, drops, signatures.
Events: freshness, lag, consumer health, DLQ.
Security: expiration keys, signatures, denied requests.
Governance: active versions/deprecates, contract compatibility.

15) Playbook incidents

A. Growth of p95 latency P0

1. Enable P0 and P2-throttle priority; 2) scale gateways;

2. Switch part of the reads to the cache 4) analysis of "hot" routes.

B. Delivery webhook drop

1. Check signatures/hour shift, 2) increase retrays/timeouts,

2. turn on the batches, 4) temporarily switch to the bullet endpoint.

C. Drift contracts

1. Enable "strict mode,"

2. notify the producer, 3) release the adapter, 4) post-mortem, update the linters.

D. Key/cert compromise

1. Revoke/rotate, 2) replay webhooks, 3) audit, 4) notify partners.

E. Repeat/Take Explosion

1. Check Idempotency-Key/TTL, 2) strengthen the deadup, 3) limit the "noisy" source.

16) Implementation checklist

1. Describe contracts (OpenAPI/AsyncAPI/IDL), include linters and CI.
2. Configure auth (OAuth2/OIDC, mTLS), webhook signatures, key rotation.
3. Enter quotas/QoS/limits, heavy-query-guard and backpressure.
4. Raise observability: SLI/SLO, tracks, dashboards, alerts.
5. Organize releases: canary/blue-green, schema-first migrations.
6. Start the version/event/key directory and deprecate processes.
7. Conduct chaos/perf/security tests, arrange playbooks.
8. Regularly revamp data minimization and regulatory compliance.

17) Glossary

Contract-first - API design through formal contracts to code.
Idempotency-Key - a key that makes the operation repeated safely.
AsyncAPI - specification of event interfaces.
QoS - Quality of Service/Priority Class.
DLQ - "dead queue" for problem messages.
Error budget burn - the rate of "burning" the error budget relative to SLO.

Bottom line: the ecosystem API is not a set of endpoints, but a managed system of contracts, security, quotas and observability. By following this framework, the ecosystem gains fast integrations, predictable SLOs, and safe evolution without downtime - from the network layer and authentication to event flows and reporting.