madhur4127 / rabbitmq-last-value-per-topic-queue

A plugin for RabbitMQ that enables creation of queues that only store and send the last received value per topic

RabbitMQ last key value queue

This code provides new type of queue, which is replaces elements in queue by key. It is helpful to update queue by newest elements (some ticks, real-time data and etc).

Example of work:

Presentation of queue is [ Head, SecondElement, ... LastElememt ]

Head is going to as next data for consumers

Initial state:

{key_1, value_1},{key_2, value_2},

Step 1: Add new non existed element {key_3, value_3} :

{key_1, value_1}, {key_2, value_2}, {key_3, value_3}

Step 2: Updating element {key_1, new_value_1}:

{key_2, value_2}, {key_3, value_3}, {key_1, new_value_1}

Usage

Initialisation

Before using you must define this queue. Queue will be created by this module if you will provide specific key for argument (options) of creation command: x-last-value-per-topic = 'enabled'

Puting of element

You must provide key of element in routing_key options within putting operation.

Examples of code

All examples of python's code for usage this queue (and tests) are available in test folder.

Installation instructions

Easiest thing to do is to:

• make run-broker from above, check that you see "started with 1 plugins", then stop the process
• copy plugins/rabbit_topic_last_value_queue-[version].ez in to the plugins directory for your installation (usually /usr/lib/rabbitmq/plugins/)
• you should now see the plugin when you do rabbitmq-plugins list and can enable/disable it using that tool

If you need any more info in installing plugins and/or troubleshooting then refer to:

• https://www.rabbitmq.com/plugins.html

• https://www.rabbitmq.com/community-plugins.html

Testing

See test/TEST_PLAN.md

Launching of test

1. make run-broker <- start RMQ
2. go to python folder and start consumer.py and producer.py

Authors

Sergey Loguntsov [email protected]

Mark Hingston [email protected]