This has already been answered by Pal. As the Voltaire phase progresses, there will be a gradual transition from the current system where spending keys are in the hands of the federation of entities developing the protocol to a system based on on-chain voting by all stakeholders.
AC1404441027 activity
AC1404441027 commented on 1.) How and where are transaction fees calculated exactly. Had this post in the forum. https://forum.cardano.org/t/variable-fees-on-cardano/95517?u=heptasean The theoretical maximum transaction fee should be 0.876 ADA, but Daedalus automatically used 1.19 ADA (although he was probably far from the m... Read more
1) The calculation of fees is described here and is essentially unchanged: https://iohk.io/en/blog/posts/2017/10/19/how-cardanos-transaction-fees-work/ You also need to add the mechanism for calculating the ada to be added to the token bundle, if any: https://cardano-ledger.readthedocs.io/en/latest/explanations/min-utxo-alonzo.html 2) Depending on the OS used cardano-node and cardano-cli communicate via unix sockets or via a named pipe. The details of the communication protocol are described here: https://docs.cardano.org/explore-cardano/cardano-network/networking-protocol You should also understand the serialization format used, CBOR.