[
https://issues.apache.org/jira/browse/CAMEL-23419?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Michael Weiss updated CAMEL-23419:
----------------------------------
Description:
The nats consumer does not seem to work in pull mode (which is the default).
Example:
{noformat}
- route:
from:
uri: nats
parameters:
jetstreamEnabled: true
jetstreamName: test
durableName: camel
servers: nats:4222
topic: "456"
steps:
- log:
message: ${body}{noformat}
--> Default is pull mode, but Camel does not pull any messages from nats
although messages are available in the nats consumer (on the server):
{noformat}
╭───────────────────────────────────────────────────────────────────────────────────────────────╮
│ Consumers
│
├───────────────┬─────────────┬─────────────────────┬─────────────┬─────────────┬───────────────┤
│ Name │ Description │ Created │ Ack Pending │ Unprocessed
│ Last Delivery │
├───────────────┼─────────────┼─────────────────────┼─────────────┼─────────────┼───────────────┤
│ camel-durable │ │ 2026-05-05 13:39:45 │ 0 │ 46
│ never │
╰───────────────┴─────────────┴─────────────────────┴─────────────┴─────────────┴───────────────╯
{noformat}
When enabling push mode explicitly with parameter `pullSubscription: false` it
consumes the messages.
The problem: the push mode doesn't scale. The consuming client (Camel) is not
able to utilize backpressure mechanisms in push mode. The nats project
recommends pull over push mode
[here|https://docs.nats.io/nats-concepts/jetstream/consumers#dispatch-type-pull-push]
Tested with nats jetstream server 2.12.4
was:
The nats consumer does not seem to work in pull mode (which is the default).
Example:
{noformat}
- route:
from:
uri: nats
parameters:
jetstreamEnabled: true
jetstreamName: test
durableName: camel
servers: nats:4222
topic: "456"
steps:
- log:
message: ${body}{noformat}
--> Default is pull mode, but Camel does not pull any messages from nats
although messages are available in the nats consumer (on the server):
{noformat}
╭───────────────────────────────────────────────────────────────────────────────────────────────╮
│ Consumers
│
├───────────────┬─────────────┬─────────────────────┬─────────────┬─────────────┬───────────────┤
│ Name │ Description │ Created │ Ack Pending │ Unprocessed
│ Last Delivery │
├───────────────┼─────────────┼─────────────────────┼─────────────┼─────────────┼───────────────┤
│ camel-durable │ │ 2026-05-05 13:39:45 │ 0 │ 46
│ never │
╰───────────────┴─────────────┴─────────────────────┴─────────────┴─────────────┴───────────────╯
{noformat}
When enabling push mode explicitly with parameter `pullSubscription: false` it
consumes the messages.
The problem: the push mode doesn't scale. The consumer (Camel) cannot utilize
backpressure mechanisms in push mode. The nats project recommends pull over
push mode
[here|https://docs.nats.io/nats-concepts/jetstream/consumers#dispatch-type-pull-push]
Tested with nats jetstream server 2.12.4
> camel-nats - Consumer does not work in pull mode
> ------------------------------------------------
>
> Key: CAMEL-23419
> URL: https://issues.apache.org/jira/browse/CAMEL-23419
> Project: Camel
> Issue Type: Bug
> Components: camel-nats
> Affects Versions: 4.18.1
> Reporter: Michael Weiss
> Assignee: Andrea Cosentino
> Priority: Minor
> Fix For: 4.18.3, 4.21.0
>
>
> The nats consumer does not seem to work in pull mode (which is the default).
> Example:
> {noformat}
> - route:
> from:
> uri: nats
> parameters:
> jetstreamEnabled: true
> jetstreamName: test
> durableName: camel
> servers: nats:4222
> topic: "456"
> steps:
> - log:
> message: ${body}{noformat}
> --> Default is pull mode, but Camel does not pull any messages from nats
> although messages are available in the nats consumer (on the server):
> {noformat}
> ╭───────────────────────────────────────────────────────────────────────────────────────────────╮
> │ Consumers
> │
> ├───────────────┬─────────────┬─────────────────────┬─────────────┬─────────────┬───────────────┤
> │ Name │ Description │ Created │ Ack Pending │
> Unprocessed │ Last Delivery │
> ├───────────────┼─────────────┼─────────────────────┼─────────────┼─────────────┼───────────────┤
> │ camel-durable │ │ 2026-05-05 13:39:45 │ 0 │
> 46 │ never │
> ╰───────────────┴─────────────┴─────────────────────┴─────────────┴─────────────┴───────────────╯
> {noformat}
>
> When enabling push mode explicitly with parameter `pullSubscription: false`
> it consumes the messages.
> The problem: the push mode doesn't scale. The consuming client (Camel) is not
> able to utilize backpressure mechanisms in push mode. The nats project
> recommends pull over push mode
> [here|https://docs.nats.io/nats-concepts/jetstream/consumers#dispatch-type-pull-push]
>
> Tested with nats jetstream server 2.12.4
>
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