RedisSMQ / Docs / Message Exchanges
Starting with version 7.1.0, RedisSMQ introduces message exchanges, which provide flexible routing methods for directing messages to one or more queues.
A message exchange functions as an address or routing algorithm that determines the destinations for a message.
Each message must be associated with a message exchange, which enables the producer to identify the list of queues that correspond to the exchange parameters.
Subsequently, the producer directly publishes the message to the matched queues.
When a message is sent to multiple queues, a unique message is created for each queue with the same properties as the original message, but each will have a different ID. All messages that are created and published to multiple queues through a specific message exchange share a common Exchange Tag.
The Exchange Tag serves as a unique identifier to track all messages published to the identified queues at the moment of publication.
RedisSMQ supports three exchange types out of the box:
A direct exchange allows producers to send a message to a specific queue that exactly matches the designated exchange queue.
The queue can be specified as a string (e.g., a.b.c.d) or as an object that describes the queue's namespace
{ ns: 'my-app', name: 'a.b.c.d'}. If a string is provided, RedisSMQ will utilize the default namespace.
For example, a direct exchange targeting the queue a.b.c.d will only match the queue named exactly as a.b.c.d.
To configure a direct exchange for a message, use the ProducibleMessage Class and the method ProducibleMessage.setQueue():
const { ProducibleMessage } = require('redis-smq');
const msg = new ProducibleMessage();
msg.setQueue('a.b.c.d').setBody('123456789');When publishing a message with a direct exchange, if the target queue does not exist, the message will not be sent, and an error will be returned.
To retrieve the list of queues associated with a direct exchange, utilize ExchangeDirect.getQueues().
For further details, visit:
A topic exchange allows messages to be published to one or multiple queues that match a specified topic pattern.
The topic pattern is a string composed of alphanumeric characters, including - and _, separated by periods (.).
For instance, the topic pattern a.b.c.d will match the following queues: a.b.c.d, a.b.c.d.e, and a.b.c.d.e.f, but it will not match a.b, a.b.c, or a.b.c.z.
A topic pattern can also be represented as an object to denote the namespace:
{ ns: 'my-app', topic: 'a.b.c.d' }This will match all queues within the my-app namespace that satisfy the a.b.c.d pattern. If no namespace is specified, the default namespace will be applied.
To set up a topic exchange for a message, use the ProducibleMessage Class and the method ProducibleMessage.setTopic():
const { ProducibleMessage } = require('redis-smq');
const msg = new ProducibleMessage();
msg.setTopic('a.b.c.d').setBody('123456789');If the topic pattern does not correspond to any queues, the message will be deleted and an error will be generated.
To fetch the list of queues associated with a topic exchange, employ ExchangeTopic.getQueues().
For more information, refer to:
A FanOut exchange enables producers to publish a message to all queues that are bound to the exchange via a binding key. Usage
To use a FanOut exchange, you must first create it via ExchangeFanOut.saveExchange() and then bind one or more queues to the exchange through ExchangeFanOut.bindQueue().
To set up a FanOut exchange for a message, the ProducibleMessage API utilizes ProducibleMessage.setFanOut():
const { ProducibleMessage } = require('redis-smq');
const msg = new ProducibleMessage();
// Assuming that my-FanOut-exchange already exists
msg.setFanOut('my-FanOut-exchange').setBody('123456789');When publishing with a FanOut exchange, if the exchange does not exist or no queues are associated, the message will be discarded and an error returned.
To find out which queues are associated with a FanOut exchange, use ExchangeFanOut.getQueues().
Additionally, FanOut exchanges can be managed through the HTTP API Interface or via a browser using the Web UI.
For further details, consult: