The Grouper Messaging system interface will have a RabbitMQ implementation.
Install RabbitMQ
On windows, install erlang, then install RabbitMQ
Get the management ui working (do this as an administrator)
C:\Program Files\RabbitMQ Server\rabbitmq_server-3.6.10\sbin>rabbitmq-plugins.bat enable rabbitmq_management
Restart RabbitMQ service as an administrator (e.g. in windows in local services console)
Login to http://localhost:15672/ with guest/guest
Default port is 5672
On Mac, Download RabbitMQ from https://www.rabbitmq.com/install-standalone-mac.html. Unzip the file and go to sbin directory. Run ./rabbitmq-server. It will launch rabbimq server.
Login to http://localhost:15672/ with guest/guest
Note: Grouper Rabbitmq messaging doesn't support acknowledging the individual messages.