There's some confusion throughout the codebase about wether the outputData field of the protobuf is treated as a string or as bytes. This field is used to populate result.outputdata() which we usually want to manipulate/display/return to the user. As a consequence, I think it make sense to make the parameter a string.

The only reason we can't really do this with inputData just yet, is because for the code generation we set the inputdata to the WASM file (as a byte array).