Specs are quantitative aspects of the option such as the price
Pros
Pro
Open Source
RabbitMQ is licensed under the Mozilla Public License. Because it's such a core part of a system, it's better that it's open source to avoid expensive licensing or consulting fees.
Messages in RabbitMQ are sent to a central broker before being passed to clients. This makes RabbitMQ a better choice if you are in need of more complicated methods of message passing such as routing and load balancing.