Redis Simple Message Queue

A lightweight message queue for Node.js that requires no dedicated queue server. Just a Redis server.

tl;dr: If you run a Redis server and currently use Amazon SQS or a similar message queue you might as well use this fast little replacement. Using a shared Redis server multiple Node.js processes can send / receive messages.

Features

• Lightweight: Just Redis and ~500 lines of javascript. redis is the only dependency.
• Speed: Send/receive 10000+ messages per second on an average machine. It's just Redis.
• Guaranteed delivery of a message to exactly one recipient within a messages visibility timeout.
• Received messages that are not deleted will reappear after the visibility timeout.
• Test coverage: see the test folder.
• A message is deleted by the message id. The message id is returned by the sendMessage and receiveMessage method.
• Messages stay in the queue unless deleted.
• Optional RESTful interface via rest-rsmq
• Typescript Typings ❤️
• Optional Promise-based API (only if Promise is defined), just suffix your method with Async, eg: sendMessage -> sendMessageAsync, all queue methods are supported

Note: RSMQ uses the Redis EVAL command (LUA scripts) so the minimum Redis version is 2.6+. The minimum supported Node.js version is 20.

Usage

• After creating a queue you can send messages to that queue.
• The messages will be handled in a FIFO (first in first out) manner unless specified with a delay.
• Every message has a unique id that you can use to delete the message.
• The sendMessage method will return the id for a sent message.
• The receiveMessage method will return an id along with the message and some stats.
• Should you not delete the message it will be eligible to be received again after the visibility timeout is reached.
• Please have a look at the createQueue and receiveMessage methods described below for optional parameters like visibility timeout and delay.

Installation

npm install rsmq

Modules for RSMQ

To keep the core of RSMQ small additional functionality is available as modules:

• rsmq-worker Helper to implement a worker with RSMQ.
• rest-rsmq A RESTful interface for RSMQ.
• rsmq-cli A command-line interface / Terminal client for RSMQ.
• rsmq-promise-native Native promise interface for RSMQ.
• rsmq-promise Promise interface for RSMQ (via Bluebird).

RSMQ in other languages

The simplicity of RSMQ is useful in other languages. Here is a list of implementations in other languages:

• Rust RSMQ Async for Rust. See #107
• Java RSMQ for Java. See #48
• PHP RSMQ for PHP (work in progress)
• CSharp/DotNet RSMQ for .NET

Note: Should you plan to port RSQM to another language please make sure to have tests to ensure compatibility with all RSMQ clients. And of course: let me know so i can mention your port here.

Methods

Constructor

Creates a new instance of RSMQ.

Parameters:

• host (String): optional (Default: "127.0.0.1") The Redis server
• port (Number): optional (Default: 6379) The Redis port
• options (Object): optional (Default: {}) The Redis options object. It is passed on to redis.createClient, so options like db, tls or retry_strategy can be set here.
• client (RedisClient): optional A existing redis client instance. host and server will be ignored.
• ns (String): optional (Default: "rsmq") The namespace prefix used for all keys created by RSMQ
• realtime (Boolean): optional (Default: false) Enable realtime PUBLISH of new messages (see the Realtime section)
• password (String): optional (Default: null) If your Redis server requires a password supply it here

Example:

const RedisSMQ = require("rsmq");
const rsmq = new RedisSMQ( {host: "127.0.0.1", port: 6379, ns: "rsmq"} );

Queue

createQueue(options, callback)

Create a new queue.

Parameters:

• qname (String): The Queue name. Maximum 160 characters; alphanumeric characters, hyphens (-), and underscores (_) are allowed.
• vt (Number): optional (Default: 30) The length of time, in seconds, that a message received from a queue will be invisible to other receiving components when they ask to receive messages. Allowed values: 0-9999999 (around 115 days)
• delay (Number): optional (Default: 0) The time in seconds that the delivery of all new messages in the queue will be delayed. Allowed values: 0-9999999 (around 115 days)
• maxsize (Number): optional (Default: 65536) The maximum message size in bytes. Allowed values: 1024-65536 and -1 (for unlimited size)

Returns:

• 1 (Number)

Example:

rsmq.createQueue({ qname: "myqueue" }, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	if (resp === 1) {
		console.log("queue created")
	}
});

listQueues(options, callback)

List all queues

Returns an array:

• ["qname1", "qname2"]

Example:

rsmq.listQueues(function (err, queues) {
	if (err) {
		console.error(err)
		return
	}

	console.log("Active queues: " + queues.join( "," ) )
});

deleteQueue(options, callback)

Deletes a queue and all messages.

Parameters:

• qname (String): The Queue name.

Returns:

• 1 (Number)

Example:

rsmq.deleteQueue({ qname: "myqueue" }, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	if (resp === 1) {
		console.log("Queue and all messages deleted.")
	} else {
		console.log("Queue not found.")
	}
});

getQueueAttributes(options, callback)

Get queue attributes, counter and stats

Parameters:

• qname (String): The Queue name.

Returns an object:

• vt (Number): The visibility timeout for the queue in seconds
• delay (Number): The delay for new messages in seconds
• maxsize (Number): The maximum size of a message in bytes
• totalrecv (Number): Total number of messages received from the queue
• totalsent (Number): Total number of messages sent to the queue
• created (Number): Timestamp (epoch in seconds) when the queue was created
• modified (Number): Timestamp (epoch in seconds) when the queue was last modified with setQueueAttributes
• msgs (Number): Current number of messages in the queue
• hiddenmsgs (Number): Current number of hidden / not visible messages. A message can be hidden while "in flight" due to a vt parameter or when sent with a delay

Example:

rsmq.getQueueAttributes({ qname: "myqueue" }, function (err, resp) {
	if (err) {
		console.error(err);
		return;
	}

	console.log("==============================================");
	console.log("=================Queue Stats==================");
	console.log("==============================================");
	console.log("visibility timeout: ", resp.vt);
	console.log("delay for new messages: ", resp.delay);
	console.log("max size in bytes: ", resp.maxsize);
	console.log("total received messages: ", resp.totalrecv);
	console.log("total sent messages: ", resp.totalsent);
	console.log("created: ", resp.created);
	console.log("last modified: ", resp.modified);
	console.log("current n of messages: ", resp.msgs);
	console.log("hidden messages: ", resp.hiddenmsgs);
});

setQueueAttributes(options, callback)

Sets queue parameters.

Parameters:

• qname (String): The Queue name.
• vt (Number): optional * The length of time, in seconds, that a message received from a queue will be invisible to other receiving components when they ask to receive messages. Allowed values: 0-9999999 (around 115 days)
• delay (Number): optional The time in seconds that the delivery of all new messages in the queue will be delayed. Allowed values: 0-9999999 (around 115 days)
• maxsize (Number): optional The maximum message size in bytes. Allowed values: 1024-65536 and -1 (for unlimited size)

Note: At least one attribute (vt, delay, maxsize) must be supplied. Only attributes that are supplied will be modified.

Returns an object:

• vt (Number): The visibility timeout for the queue in seconds
• delay (Number): The delay for new messages in seconds
• maxsize (Number): The maximum size of a message in bytes
• totalrecv (Number): Total number of messages received from the queue
• totalsent (Number): Total number of messages sent to the queue
• created (Number): Timestamp (epoch in seconds) when the queue was created
• modified (Number): Timestamp (epoch in seconds) when the queue was last modified with setQueueAttributes
• msgs (Number): Current number of messages in the queue
• hiddenmsgs (Number): Current number of hidden / not visible messages. A message can be hidden while "in flight" due to a vt parameter or when sent with a delay

Example:

rsmq.setQueueAttributes({ qname: "myqueue", vt: "30"}, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	console.log("changed the invisibility time of messages that have been received to 30 seconds");
	console.log(resp);
});

Messages

sendMessage

Sends a new message.

Parameters:

• qname (String)
• message (String)
• delay (Number): optional (Default: queue settings) The time in seconds that the delivery of the message will be delayed. Allowed values: 0-9999999 (around 115 days)

Note: The message length is checked against the maxsize of the queue in bytes (UTF-8), not in characters. A message of 40000 Emoji characters is 160000 bytes long and will be rejected by a queue with the default maxsize of 65536.

Returns:

• id (String): The internal message id.

Example:

rsmq.sendMessage({ qname: "myqueue", message: "Hello World "}, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	console.log("Message sent. ID:", resp);
});

receiveMessage(options, callback)

Receive the next message from the queue.

Parameters:

• qname (String): The Queue name.
• vt (Number): optional (Default: queue settings) The length of time, in seconds, that the received message will be invisible to others. Allowed values: 0-9999999 (around 115 days)

Returns an object:

• message (String): The message's contents.
• id (String): The internal message id.
• sent (Number): Timestamp of when this message was sent / created.
• fr (Number): Timestamp of when this message was first received.
• rc (Number): Number of times this message was received.

Note: Will return an empty object if no message is there

Example:

rsmq.receiveMessage({ qname: "myqueue" }, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	if (resp.id) {
		console.log("Message received.", resp)
	} else {
		console.log("No messages for me...")
	}
});

deleteMessage(options, callback)

Parameters:

• qname (String): The Queue name.
• id (String): message id to delete.

Returns:

• 1 if successful, 0 if the message was not found (Number).

Example:

rsmq.deleteMessage({ qname: "myqueue", id: "dhoiwpiirm15ce77305a5c3a3b0f230c6e20f09b55" }, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	if (resp === 1) {
		console.log("Message deleted.")
	} else {
		console.log("Message not found.")
	}
});

popMessage(options, callback)

Receive the next message from the queue and delete it.

Important: This method deletes the message it receives right away. There is no way to receive the message again if something goes wrong while working on the message.

Parameters:

• qname (String): The Queue name.

Returns an object:

• message (String): The message's contents.
• id (String): The internal message id.
• sent (Number): Timestamp of when this message was sent / created.
• fr (Number): Timestamp of when this message was first received.
• rc (Number): Number of times this message was received.

Note: Will return an empty object if no message is there

Example:

rsmq.popMessage({ qname: "myqueue" }, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	if (resp.id) {
		console.log("Message received and deleted from queue", resp)
	} else {
		console.log("No messages for me...")
	}
});

changeMessageVisibility(options, callback)

Change the visibility timer of a single message. The time when the message will be visible again is calculated from the current time (now) + vt.

Parameters:

• qname (String): The Queue name.
• id (String): The message id.
• vt (Number): The length of time, in seconds, that this message will not be visible. Allowed values: 0-9999999 (around 115 days)

Returns:

• 1 if successful, 0 if the message was not found (Number).

Example:

rsmq.changeMessageVisibility({ qname: "myqueue", vt: "60", id: "dhoiwpiirm15ce77305a5c3a3b0f230c6e20f09b55" }, function (err, resp) {
	if (err) {
		console.error(err)
		return
	}

	if (resp === 1) {
		console.log("message hidden for 60 seconds")
	}
});

quit(callback)

Disconnect the redis client. This is only useful if you are using rsmq within a script and want node to be able to exit.

Events

An RSMQ instance is an EventEmitter and emits:

• connect: The Redis connection is up. The LUA scripts are being loaded.
• disconnect: The Redis connection was refused or lost (ECONNREFUSED).
• error: Any other error of the Redis client. The error object is passed to the listener. Without a listener the error is only written to console.error and RSMQ will not throw.

rsmq.on("error", function (err) {
	console.error("RSMQ error", err);
});

Realtime

When initializing RSMQ you can enable the realtime PUBLISH for new messages. On every new message that gets sent to RSQM via sendMessage a Redis PUBLISH will be issued to {rsmq.ns}:rt:{qname}.

Example for RSMQ with default settings:

• The queue testQueue already contains 5 messages.
• A new message is being sent to the queue testQueue.
• The following Redis command will be issued: PUBLISH rsmq:rt:testQueue 6

How to use the realtime option

Besides the PUBLISH when a new message is sent to RSMQ nothing else will happen. Your app could use the Redis SUBSCRIBE command to be notified of new messages and issue a receiveMessage then. However make sure not to listen with multiple workers for new messages with SUBSCRIBE to prevent multiple simultaneous receiveMessage calls.

Changes

see the CHANGELOG

Other projects

Name	Description
node-cache	Simple and fast Node.js internal caching. Node internal in memory cache like memcached.
redis-tagging	A Node.js helper library to make tagging of items in any legacy database (SQL or NoSQL) easy and fast.
redis-sessions	An advanced session store for Node.js and Redis
rsmq-worker	Helper to implement a worker based on RSMQ (Redis Simple Message Queue).
connect-redis-sessions	A connect or express middleware to use redis sessions that lets you handle multiple sessions per user_id.

The MIT License

Please see the LICENSE.md file.