NATS sink

The NATS sink publishes messages to NATS subjects.

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Configuration

• Host

  The hostname of your NATS server (e.g., localhost).

• Port

  The port number for your NATS server (default: 4222).

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Message format

Sequin sends messages to SQS as JSON. You can find the shape of the messages in the messages reference.

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Subject naming

Messages are published to subjects using the following patterns:

For change events:

sequin.changes.<database_name>.<schema_name>.<table_name>.<action>

For record events:

sequin.rows.<database_name>.<schema_name>.<table_name>

For example, if you’re streaming changes from a table called products in the public schema of a database called shop, you would see routing keys like:

• sequin.changes.shop_prod.public.products.insert
• sequin.changes.shop_prod.public.products.update
• sequin.changes.shop_prod.public.products.delete

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Message headers

Each message includes the following NATS headers:

• Nats-Msg-Id: A unique Sequin identifier for the message

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Retry behavior

If Sequin is unable to deliver a message to NATS, it will retry the message indefinitely. Sequin will exponentially back off the retry interval, with a maximum backoff of roughly 3 minutes.

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Message ordering

NATS preserves message order within a subject. Messages are published to NATS subjects in the same order that they are received from your source table.

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Debugging

You can view the status of your NATS sink in the Sequin web console.

On the “Messages” tab, you can see which messages are in-flight to NATS, which messages Sequin is unable to deliver, and recently delivered messages.

Messages that Sequin is unable to deliver will have a “Deliver count” greater than 1. You can click on a message to see more details, including the last error response received from NATS.