# Method Protocols.HTTP.Session()->Request()->set_callbacks()

Method set_callbacks

  `void set_callbacks(function(mixed ... :mixed) headers, function(mixed ... :mixed) data, function(mixed ... :mixed) fail, mixed ... callback_arguments)`

Description

  Setup callbacks for async mode, headers will be called when the request got connected, and got data headers; data will be called when the request got the amount of data it's supposed to get and fail is called whenever the request failed.

  Note here that an error message from the server isn't considered a failure, only a failed TCP connection.