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RabbitMQ Bus implementation
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Introduction
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As part of the Distributed Data annex, I shall integrate RabbitMQ into my Ramses project to enable scalability, minimize coordination, redundancy & readiness for evolution. Within Ramses a few integration patterns are used(there are more, I don't know each one as there are over 40.):

- Topics and subscription
- Point to point: Queues(relevant)
- Micro Services
- Messaging
- Transformation(relevant)

Execution
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In order to integrate rabbit mq into my back-end REST spring boot API I first created an overview of the inner communication that was required.

.. image:: https://i.imgur.com/oMlWygP.png

I then began by creating my Ramses exchange in RabbitMQ.

.. image:: https://i.imgur.com/s0oCMaR.png

And then implemented the connection string into my application properties.

.. code-block:: yaml

    spring.rabbitmq.host=10.0.0.34
    spring.rabbitmq.port=5672
    spring.rabbitmq.virtual-host=/
    #todo add secrets to env file
    spring.rabbitmq.username=guest
    spring.rabbitmq.password=guest
    spring.rabbitmq.exchange=ramses.exchange
    #spring.rabbitmq.routingkey=ramses.routingkey
    spring.rabbitmq.queue=ramses.queue

This is a required change in both CommentService & GameService. 

I then created a CommentDTO in my GameService (Transformation) in order to be able to handle creating a list of comments based off of the messages in the queue later on.

.. code-block:: javascript

    public class Comment  {

    private int Id;
    private String CommentMessage;
    private int gameId;


These attributes correspond with the comment model in the Comment Microservice. In my non-trivial microservice page found here: https://se6.oksolution.nl/learning/scaling/nontrivial.html I elaborated further on my implementation of the rabbitmq configuration. 

One thing unmentioned in this about the implementation is the adjustments made to the GameController & CommentMessageController 

.. code-block:: javascript
    :caption: GameController (GameService)

    @GetMapping("/{id}/comment")
    public List<Comment> getAllComments(@PathVariable final int id) {
        //final Optional<Game> game = _GameCollection.getGame(id);
        return _GameCollection.getGameComments(id);
        //return _rabbitSender.getAllComments(id);
        //return (List<Comment>) _GameCollection.getGame(id).map(p-> {
        //    _GameCollection.getGameComments(id);
        //    return ResponseEntity.noContent().build();
        //}).orElseThrow(()-> new NoResultException());
    }

I left the comments if I'd need to debug another time.

.. code-block:: javascript
    :caption: CommentMessageController (CommentService)

    @RabbitListener(queues = "getAllComments")
    public List<Comment> getComments(
                                     String id
    ){
        int realId = Integer.parseInt(id);
        List<Comment> allCommentsFromGame = commentcollection.getAllGameComments(realId);

        //List<Comment> comments = commentcollection.getAllComments();
        //List<Comment> test_comments = commentcollection.getGameComments(id);
        //return test_comments;

        return allCommentsFromGame;
    }

I don't understood why but the id being passed from the queue was being parsed only as a string. I assume the usual use-case is to parse UUIDs into the IDs. Here too are comments stored in case I'd need to debug it again.

I initially made a mistake setting up my Comment DTO which I found out later after long periods of debugging, the getters & setters were missing. 

Here is the getAllComments queue during a load test:

.. image:: https://i.imgur.com/M1UAj4E.png