I want to exchange not monetary values, but serialisable Plain Old Data Structs (say 4 int32 and char array of 128 items) in each message. One can not sum two of these values directly, yet can take two and produce a new one. So some way of restricting the operations set is needed.
What one shall change in stellar-core to achieve such change and have consensus and transactions available?
Do I only have to change .xdr value definition and regenerate code or it is more complicated and some other parts must be changed?