Responding over a TCP socket using :gen_tcp

Now that we know how to use :gen_tcp to initiate a TCP/IP connection, the next step is to respond using that connection. In order to respond to a request, we will be using the :gen_tcp.send/2 function.

The :gen_tcp.send/2 function allows us to send I/O data (generally string) on a connection socket. It doesn’t support send timeout, so it only takes a connection socket and data that needs to be sent. We can use the connection socket returned by the :gen_tcp.accept/1 call in the previous section to send an HTTP response.

In order to send data over a connection socket, let’s restructure our ExperimentServer module:

experiment_server.exs

defmodule ExperimentServer do
  require Logger
  def start(port) do
    listener_options = [
    active: false,
    packet: :http_bin,
    reuseaddr: true
  ]
   ...