rsmq

A really simple message queue based on Redis

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.
Speed: Send and receive 1000+ 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
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

Note: RSMQ uses the Redis EVAL command (LUA scripts) so the minimum Redis version is 2.6+.

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-rsqm A RESTful interface for RSMQ.
rsmq-cli A command-line interface / Terminal client for RSMQ.

Example

Initialize

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

Parameters for RedisSMQ via an options object:

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 https://github.com/mranney/node_redis#rediscreateclientport-host-options options object.
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

Create a queue

Please look at the Methods section for optional parameters when creating a queue.

rsmq.createQueue({qname:"myqueue"}, function (err, resp) {
        if (resp===1) {
            console.log("queue created")
        }
});

Send a message

rsmq.sendMessage({qname:"myqueue", message:"Hello World"}, function (err, resp) {
    if (resp) {
        console.log("Message sent. ID:", resp);
    }
});

Receive a message

rsmq.receiveMessage({qname:"myqueue"}, function (err, resp) {
    if (resp.id) {
        console.log("Message received.", resp)	
    }
    else {
        console.log("No messages for me...")
    }
});

Delete a message

rsmq.deleteMessage({qname:"myqueue", id:"dhoiwpiirm15ce77305a5c3a3b0f230c6e20f09b55"}, function (err, resp) {
    if (resp===1) {
        console.log("Message deleted.")	
    }
    else {
        console.log("Message not found.")
    }
});

Methods

changeMessageVisibility

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.

createQueue

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

Returns:

deleteMessage

Parameters:

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

Returns:

1 if successful, 0 if the message was not found.

deleteQueue

Deletes a queue and all messages.

Parameters:

qname (String): The Queue name.

Returns:

getQueueAttributes

Get queue attributes, counter and stats

Parameters:

qname (String): The Queue name.

Returns an object:

vt: The visibility timeout for the queue in seconds
delay: The delay for new messages in seconds
maxsize: The maximum size of a message in bytes
totalrecv: Total number of messages received from the queue
totalsent: Total number of messages sent to the queue
created: Timestamp (epoch in seconds) when the queue was created
modified: Timestamp (epoch in seconds) when the queue was last modified with setQueueAttributes
msgs: Current number of messages in the queue
hiddenmsgs: 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

listQueues

List all queues

Returns an array:

["qname1", "qname2"]

popMessage

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

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

receiveMessage

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

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

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)

Returns:

id: The internal message id.

setQueueAttributes

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

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

Returns an object:

vt: The visibility timeout for the queue in seconds
delay: The delay for new messages in seconds
maxsize: The maximum size of a message in bytes
totalrecv: Total number of messages received from the queue
totalsent: Total number of messages sent to the queue
created: Timestamp (epoch in seconds) when the queue was created
modified: Timestamp (epoch in seconds) when the queue was last modified with setQueueAttributes
msgs: Current number of messages in the queue
hiddenmsgs: 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

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