====== RabbitMQ ======

[[https://www.rabbitmq.com|RabbitMQ]] is a popular open source message broker. In a process data context, it can be used for buffering and/or routing data across networks and between servers.

Data Core supports this with two components:

  * **Rabbit MQ Producer** - Writes process data to a queue
  * **Rabbit MQ Consumer** - Reads process data from a queue

===== Getting Started =====

==== Enable RabbitMQ on Windows ====

RabbitMQ has several deployment options - below we provide our recommended approach.

**1. Install Erlang** 

//Erlang is a high-level programming language for real-time systems. It is a pre-requisite of RabbitMQ.//

Download and run the [[https://www.erlang.org/downloads|Erlang 64bit Windows Installer]].

**2. Install RabbitMQ ** 

Download and run the [[https://www.rabbitmq.com/install-windows.html#installer|RabbitMQ 64bit Windows Installer]].

When prompted, untick the "Install RabbitMQ Service" option.

{{ :data_core:rabbitmq_01.jpg?400 |}}


**3. Configure RabbitMQ**

Open "RabbitMQ Command Prompt" in admin mode and execute the following instructions.

  set RABBITMQ_BASE=%PROGRAMDATA%\RabbitMQ
  rabbitmq-service install
  rabbitmq-plugins enable rabbitmq_management
  rabbitmq-service start
   
//The above actions installs the RabbitMQ service to the ProgramData directory (rather than the default action which installs the service to a user-specific AppData folder) and enables the admin UI.//

  
**4. Enable Shovel Plugin (optional) **

//The shovel plugin is only required on servers actively pushing data downstream to another server.//

Open **RabbitMQ Command Prompt** in admin mode and enter

  rabbitmq-service stop
  rabbitmq-plugins enable rabbitmq_shovel
  rabbitmq-plugins enable rabbitmq_shovel_management
  rabbitmq-service start
  

==== RabbitMQ Administration ====

The RabbitMQ Admin UI is accessible on

  http://localhost:15672/
  
{{ :data_core:rabbitmq_02.png?400 |}}

**Hint** Bookmark this link.
  
The default login is Guest/Guest.
\\ This account account is only permitted for localhost login. Also note port 15672 is closed by default.

===== RabbitMQ Producer =====

RabbitMQ Producer writes tag-value data to a queue. 

The default configuration writes persistent messages to a local, durable queue called "data_core.tag_values". This means messages are stored to the hard drive and will survive a server restart. 

The keys settings are:

  * **Routing Key** \\ The routing key to set on messages containing snapshot/historical tag values.


===== RabbitMQ Consumer =====

//RabbitMQ Consumer reads tag-value data from a queue.//

The default configuration reads messages from a local queue called “data_core.tag_values”. The driver will create this queue if it doesn't already exist.

The keys settings are:

  * **Queue Names** \\ A comma-delimited list of RabbitMQ queues to read tag values and/or event messages from.



===== More RabbitMQ Resources =====

  * [[DataCore:Enable Resilient Data Transfer with RabbitMQ]]
  * [[DataCore:Enable Resilient Data Transfer with RabbitMQ - "Fast Flow" Variation]] 
  * [[https://dennymichael.net/2014/06/16/rabbitmq-change-the-hostname | RabbitMQ: Change the Hostname]]