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FastStream NATS support is implemented on top of nats-py. You can always get access to objects of it if you need to use some low-level methods not represented in FastStream.

Advantages and Disadvantages#

NATS is an easy-to-use, high-performance message broker written in Golang. If your application does not require complex routing logic, can cope with high loads, scales, and does not require large hardware costs, NATS will be an excellent choice for you.

Also NATS has a zero-cost new entities creation (to be honest, all subjects are just routing fields), so it can be used as a RPC over MQ tool.


More information about NATS can be found on the official website.

However, NATS has disadvantages that you should be aware of:

  • Messages are not persistent. If a message is published while your consumer is disconnected, it will be lost.
  • There are no complex routing mechanisms.
  • There are no mechanisms for confirming receipt and processing of messages from the consumer.

NATS JetStream#

These shortcomings are corrected by using the persistent level - JetStream. If you need strict guarantees for the delivery and processing of messages at the small detriment of speed and resources consumed, you can use NatsJS.

Also, NatsJS supports some high-level features like Key-Value and Object storages (with subscription to changes on it) and provides you with rich abilities to build your logic on top of it.

Routing Rules#

NATS does not have the ability to configure complex routing rules. The only entity in NATS is subject, which can be subscribed to either directly by name or by a regular expression pattern.

Both examples are discussed a little further.

In order to support the ability to scale consumers horizontally, NATS supports the queue group functionality: a message sent to subject will be processed by a random consumer from the queue group subscribed to this subject. This approach allows you to increase the processing speed of subject by N times when starting N consumers with one group.

Last update: 2023-10-02