Very similar to any traditional application, there are dependent core components that are pivotal to its functionality and not necessarily the application itself. In the case of the base OpenStack architecture, there are two core components that would be considered the core or backbone of the cloud. OpenStack functionality requires access to an SQL-based backend database service and an AMQP (Advanced Message Queuing Protocol) software platform. Just like with any other technology, OpenStack too has base supported reference architectures out there for us to follow. From a database perspective, the common choice will be MySQL and the default AMQP package is RabbitMQ. These two dependencies must be installed, configured, and functional before you can start an OpenStack deployment.
There are additional optional software packages that can also be used to provide further stability as part of your cloud design. Information about this management software and further OpenStack architecture details can be found at the following link http://docs.openstack.org/arch-design/generalpurpose-architecture.html.