httpx client used

httpx timeout config

httpx limits config

tenacity retry decorator

retry attempt count

exponential backoff params

circuitbreaker library

circuit failure threshold

circuit recovery timeout

async implementation

raise_for_status called

aiokafka producer

aiokafka consumer

JSON value serializer

DomainEvent dataclass

event_id field

event_type field

aggregate_id field

occurred_at field

data field

aggregate_id as Kafka key

topic from event_type

producer started/stopped

asdict used for publish

SagaStep class

action callable

compensation callable

SagaStatus enum

PENDING status value

COMPLETED status value

COMPENSATING status value

FAILED status value

reverse compensation order

compensation on exception

compensation failures logged/swallowed

context dict threaded through

separate service data

async saga execution

asyncio.gather used

return_exceptions=True

isinstance Exception check

@circuit decorator used

failure_threshold=5

recovery_timeout=30

HTTPException 503

httpx async client

raise_for_status called

async endpoint

circuitbreaker import

CircuitState enum

CLOSED state

OPEN state

HALF_OPEN state

failure_threshold default 5

recovery_timeout default 30

success_threshold default 2

OPEN rejects calls

OPEN to HALF_OPEN via timedelta

HALF_OPEN to CLOSED

HALF_OPEN to OPEN on failure

async call method

Separate data stores

No cross-service DB writes

Event bus publish on order created

Event bus publish on payment completed

Event bus publish on inventory reserved

DomainEvent dataclass used

event_type field present

aggregate_id field present

Async service methods

Distinct event types

Design notes explain boundaries