We propose to add the ability to plug custom mechanisms, to the driver to allow them to discover other peer drivers, and to the clients.

The goal is to enable custom driver discovery mechanisms, in addition to the pre-existing ones. In effect, discovery via UDP multicast does not work in many environments (e.g. cloud environments) and the manual configuration of the connections requires that all the peers be known in advance and so lacks flexibility.

In 6.0 only, the existing discovery mechanisms would then be refactored into specific implementations of a discovery mechanism. In 5.2.1 we wanrt ot minimize the code changes.