Process Arrow bytestream in Julia

process_dataframe.jl

using Arrow, DataFrames
using PyCall

"""
    Convert the Arrow bytestream into a DataFrame, process it, 
    and return the resulting DataFrame as a Python bytestream.
"""
function process_arrowbytes( bytes::Vector{UInt8} )::PyObject
    df = DataFrame(Arrow.Table(bytes))          # convert bytestream into a DataFrame
    result = process_dataframe( df )            # run some arbitrary function
    result_bytes = df_to_arrowbytes(results)    # convert result into Arrow bytestream
    return PyCall.pybytes(result_bytes)         # send bytestream back as a PyObject
end

"""Convert DataFrame into Arrow bytestream"""
function df_to_arrowbytes( df::DataFrame )::Vector{UInt8}
    io = IOBuffer()
    Arrow.write(io, df)
    seekstart(io)
    bytes = take!(io)
    return bytes
end