The plugin service retrieves and updates the current connection and its relevant host information.
It also keeps track of the host list provider in use, and notifies it to update its host list.
It is expected that the plugins do not establish a connection themselves, but rather call PluginService.connect()
to establish connections.
The plugin service uses the host list provider to retrieve the most recent host information or topology information about the database.
The Python Wrapper has two host list providers, the ConnectionStringHostListProvider and the RdsHostListPovider.
The ConnectionStringHostListProvider is the default provider.
The RdsHostListProvider provides information of the Aurora cluster.
It uses the current connection to track the available hosts and their roles in the cluster.
The ConnectionStringHostListProvider is a static host list provider, whereas the RdsHostListProvider is a dynamic host list provider.
A static host list provider will fetch the host list during initialization and does not update the host list afterwards,
whereas a dynamic host list provider will update the host list information based on database status.
When implementing a custom host list provider, implement either the StaticHostListProvider or the DynamicHostListProvider marker interfaces to specify its provider type.