NOTE: For JetStream, it is called delivery group in the official Golang SDK.
NATS Queue Group / JetStream Delivery Group allows messages directed at one consumer to be directed towards multiple connected clients in a load-balancing like scheme.
The consumer create parameters are
{
"ack_wait": 0,
"delivery_group": "string",
"filter_subject": "string",
"max_inflight": 0,
"max_retry": 0,
"mode": "string",
"name": "string",
"notes": "string"
}| Name | Type | Required | Restrictions | Description |
|---|---|---|---|---|
| ack_wait | integer | false | none | AckWait when specified, the number of ns to wait for ACK before retry |
| delivery_group | string | false | none | DeliveryGroup creates a consumer using a delivery group name. A consumer using delivery group allows multiple clients to subscribe under the same consumer and group name tuple. For subjects this consumer listens to, the messages will be shared amongst the connected clients. |
| filter_subject | string | false | none | FilterSubject sets the consumer to filter for subjects matching this NATs subject string See https://docs.nats.io/nats-concepts/subjects |
| max_inflight | integer | true | none | MaxInflight is max number of un-ACKed message permitted in-flight (must be >= 1) |
| max_retry | integer | false | none | MaxRetry max number of times an un-ACKed message is resent (-1: infinite) |
| mode | string | true | none | Mode whether the consumer is push or pull consumer |
| name | string | true | none | Name is the consumer name |
| notes | string | false | none | Notes are descriptions regarding this consumer |
The delivery_group field indicates that the consumer will use a delivery group.
To subscribe to messages as a consumer using a delivery group, the additional parameter delivery_group is needed when calling GET.
$ curl 'http://127.0.0.1:3001/v1/data/stream/testStream00/consumer/testConsumer00?subject_name=test-subject.01&delivery_group=testGroup00' --http2-prior-knowledge