Resource references can be shared across nodes, but they can only be used (in a NIF) on the node that created them initially and only if it’s still alive when accessed. E.g. if you generate a resource object on your node from a process, send it to another node, let the process die and receive the answer back, the resource object will not “work” anymore.
I’m currently working on refactoring resources (and now that you say it, @cpud36, the docs for this one are indeed very much lacking) as they are using a mechanism that will produce warnings and later errors in rustc.
Data is always passed by reference into NIFs as they run in the same process environment as the calling process. You could (as an alternative to using a resource object) also store the data in a binary object (e.g. using something like flatbuffers). If it’s larger than 64 bytes, its data will not be stored directly in the process environment and will not be copied either.
