[RFC] Cleanup network configuration about openhab-core HOT 2 OPEN

Yes the current network configuration is a bit of a mess and not consistently used probably also because of its limitations.
It is probably best to be able to select the default network interfaces and have the possibility to override the default values when necessary at add-on or Thing level.

I am not clear on the onlyUseOneAddress yet, although the purpose is similar, limiting the range used.

The reason for this option is explained in eclipse-archived/smarthome#6005

from openhab-core.

You can not run away from making "network" an API citizen, especially if you ever consider making better support for containers which multiply network interfaces even in most basic setups.

I've published some network api concepts 9 months ago; which actually stayed in my drawer for couple months. You can see org.connectorio.addons.network, org.connectorio.addons.network.ip and org.connectorio.addons.network.jvm.internal, primarily to see if it can be used to centralized management of network access from bindings. Usage of network api can be observed in AmsAdsInterfaceDiscoveryService.

Diving more (actually speculating), thanks to osgi ServiceFactory concept you can provide a multiplexed NetworkRegistry instance which will filter its entries based on bundles which make use of it. With this engineering trick your binding might still rely on enumerated networks, while control over access to them them is shifted somewhere else. This is essential to provide a unified way to make network access management possible, otherwise it will spread across many edges of bridges/things, probably beyond user oversight. Maybe OH is not a network router, but it does act as a hub, and depending on setup, framework role might be to interconnect incompatible networks.
I've purposely not made IpNetwork a concrete type because it can be supplied through JVM (read only). Under Linux there are ways to manage network level settings from userspace over dbus (using systemd-network or NetworkManager namespaces).
I also made one step further by not assuming IP to be only one kind of network, because i.e. RS485 or CAN interface can be used to launch network as well (hence there is NetworkInterfaceType). If you think of it even more, ZWave and many other radio standards, rely on network node concepts which are flattened to thing instances. In case of matter you might even have an overlay network which span from zigbee radio to ip layer.

I know all above is over-engineered, especially for my own needs, but its not about me, but platform view. ;-)

from openhab-core.