Sink data to NATS

This guide describes how to sink data from RisingWave to NATS subjects using the NATS sink connector in RisingWave.

NATS is an open source messaging system for cloud native applications. It provides a lightweight publish-subscribe architecture for high performance messaging.

Beta Feature

The NATS sink connector in RisingWave is currently in Beta. Please contact us if you encounter any issues or have feedback.

Prerequisites

Before sinking data from RisingWave to NATS, please ensure the following:

• The RisingWave cluster is running.
• A NATS server is running and accessible from your RisingWave cluster.
• Create a NATS subject that you want to sink data to.
• You have the permission to publish data to the NATS subject.

Syntax

To sink data from RisingWave to a NATS subject, create a sink using the syntax below:

CREATE SINK [ IF NOT EXISTS ] sink_name
[FROM sink_from | AS select_query]
WITH (
   connector='nats',
   server_url='<your nats server>:<port>', [ <another_server_url_if_available>, ...]
   subject='<your subject>',

 -- optional parameters
   connect_mode=<connect_mode>
   username='<your user name>',
   password='<your password>'
   jwt=`<your jwt>`,
   nkey=`<your nkey>`
);

After the sink is created, RisingWave will continuously sink data to the NATS subject in append-only mode.

note

The NATS sink connector in RisingWave provides at-least-once delivery semantics. Events may be redelivered in case of failures.

note

According to the NATS documentation, stream names must adhere to subject naming rules as well as being friendly to the file system. Here are the recommended guidelines for stream names:

• Use alphanumeric values.
• Avoid spaces, tabs, periods (.), greater than (>) or asterisks (*).
• Do not include path separators (forward slash or backward slash).
• Keep the name length limited to 32 characters as the JetStream storage directories include the account, stream name, and consumer name.
• Avoid using reserved file names like NUL or LPT1.
• Be cautious of case sensitivity in file systems. To prevent collisions, ensure that stream or account names do not clash due to case differences. For example, Foo and foo would collide on Windows or macOS systems.

Parameters

Field	Notes
server_url	Required. URLs of the NATS server, in the format of address:port. If multiple addresses are specified, use commas to separate them.
subject	Required. NATS subject that you want to sink data to.
connect_mode	Required. Authentication mode for the connection. Allowed values: plain: No authentication; user_and_password: Use user name and password for authentication. For this option, username and password must be specified; credential: Use JSON Web Token (JWT) and NKeys for authentication. For this option, jwt and nkey must be specified.
jwt and nkey	JWT and NKEY for authentication. For details, see JWT and NKeys.
username and password	Conditional. The client user name and pasword. Required when connect_mode is user_and_password.