Hi,
D3 uses data as arrays, which can be loaded (or saved) as JSON objects or .CSV files. Which one do you intend to use?
But a process of loading and sending a data is not a D3.js task. It is more about server side architecture, and can be implemented with very wide range of solution, with different features and cost.
So, would you, please, describe a features you want more detailed?
BR,
Andrew