Options

The options of a call come from the options of the route's plugin (with expressions), and from the caller (query parameters and headers prefixed with x-ca-event-broker-opts-) for those the route allows (see The plugins). The admin API's try-it routes, webhooks and workflow functions take the same options, without the prefix.

Publishing

Option	Brokers
topic	Kafka, Pulsar, MQTT, and as a fallback everywhere	where to
queue	RabbitMQ (the default exchange), Artemis (anycast)
exchange, routing_key	RabbitMQ
channel	Redis pub/sub
stream	Redis streams
address, routing_type	Artemis	multicast or anycast
key	Kafka (record key), Artemis (group id)	an event's partitionkey is its key too
partition	Kafka
qos, retained	MQTT
priority, ttl, delay, deliver_at, durable	Artemis
source, type, subject	all	the attributes a request does not give
lines	all	read the body line by line

Subscribing

Option	Brokers
topic, topics	Kafka, Pulsar, MQTT, everywhere	topics: comma separated
queue	RabbitMQ, Artemis (anycast)
exchange, routing_key	RabbitMQ	a queue of its own, bound to them
channel	Redis pub/sub	glob patterns allowed
stream	Redis streams
address, routing_type, selector	Artemis	address::queue for a queue
group (group_id, subscription)	Kafka, Pulsar, Redis streams, MQTT 5, Artemis (multicast)
subscription_type	Pulsar	exclusive, shared, failover, key_shared
consumer	Redis streams	a named consumer of the group
from	Kafka, Pulsar, Redis streams, RabbitMQ streams	latest, earliest
from_timestamp	Kafka, Pulsar, Redis streams, RabbitMQ streams	epoch millis
offset_from, offset_to, partition	Kafka (offset_from on RabbitMQ streams too)
from_id	Redis streams	an entry id, included
stream (true)	RabbitMQ	the queue is a stream
delivery	all with acks	at-most-once, at-least-once
prefetch	RabbitMQ, Redis streams, Artemis	100
qos	MQTT
client_id, group_instance_id	Kafka

Shaping the response

Option
take, drop, duration	how many events to stream, to skip, for how long (millis)
format	cloudevents (the default) or raw
heartbeat	millis: an empty line (HTTP consumer), a comment (SSE, 15000 by default, 0 to stop)
acks, max_in_flight	websocket: acks=client, and how many events wait for theirs (100)
publish_results	websocket: answer every frame published with its result

take, drop, duration, format and heartbeat are the only options a caller may set by default.

Request reply

Option
reply_to	where the replies go: required
reply_options	how to read them, as JSON
timeout	millis, 10000