2 files changed, 61 insertions(+), 0 deletions(-)

M README.md
A lib/servy/kickstarter.ex

@@ 979,3 979,35 @@ Defined a new GenServer `Servy.SensorServer` that does long polling to periodica
 The `handle_info` function is used to trigger off a `:refresh` event every 5 seconds. The refresh event will fetch from the mock external API and store the results into a cache.
 
 Be sure to add a `handle_info` function that is generic after adding the new `:refresh` handler, in order to make your server robust to crashes (a new message of `:boom` will throw a FunctionClauseError because nothing will match with `:boom` otherwise).
+
+### Linking Processes
+
+When an Elixir process terminates, it will notify its linked processes by sending it an exit signal.
+If the process terminates normally, the exit signal reason is the atom `:normal`.
+Because the process exits normally, the linked process does not terminate.
+
+If the process has an abnormal termination, the exit reason will be anything other than `:normal`. By default, the exit signal indicates that the process terminated abnormally and the linked process will terminate with the same reason *unless* the linked process is trapping exits.
+
+Linked processes are always bidirectional.
+
+#### Linking Tasks
+
+Referring back to `Task.async` for spawning functions and `Task.await` for waiting for the results:
+
+```elixir
+iex> pid = Task.async(fn -> Servy.Tracker.get_location("bigfoot") end)
+
+iex> Task.await(pid)
+%{lat: "29.0469 N", lng: "98.8667 W"}
+```
+
+The spawned process is automatically linked to the calling process.
+If the spawned task process crashes, then the process that calls `Task.async` will also crash.
+
+```elixir
+iex> pid = Task.async(fn -> raise "Kaboom!" end)
+
+** (EXIT from #PID<0.368.0>) evaluator process exited with reason: an exception was raised:
+    ** (RuntimeError) Kaboom!
+```
+

@@ 0,0 1,29 @@
+defmodule Servy.KickStarter do
+  use GenServer
+
+  def start do
+    IO.puts("Starting the kickstarter...")
+    GenServer.start(__MODULE__, :ok, name: __MODULE__)
+  end
+
+  def init(:ok) do
+    Process.flag(:trap_exit, true)
+    {:ok, start_server()}
+  end
+
+  def handle_info({:EXIT, _pid, reason}, _state) do
+    IO.puts("HttpServer exited (#{inspect(reason)})")
+    {:noreply, start_server()}
+  end
+
+  def start_server do
+    IO.puts("Starting the HTTP server...")
+
+    # server_pid = spawn(Servy.HttpServer, :start, [4000])
+    # Process.link(server_pid)
+    server_pid = spawn_link(Servy.HttpServer, :start, [4000])
+
+    Process.register(server_pid, :http_server)
+    server_pid
+  end
+end