BizTalk Server Management database, MessageBox databases, Tracking database, and SSO database are four databases which are used by BizTalk server runtime operations. It is the component that encapsulates and abstracts the database component and is the interface used by BizTalk Server to interact with the MessageBox. The Message Agent is a Component Object Model (COM) component that provides interfaces for publishing messages, subscribing to messages, retrieving messages, and so on. This interface is the only mechanism used by other BizTalk Server components, including the adapter framework and orchestrations, to interact with the MessageBox.