http-kit what is the difference between sending response through channel and just return a map

Question

As the title says. What is the difference between sending response through a channel and just return a map.

(defn handler-one
  [request]
  (response "hello world")

(defn handler-two
  [request]
  (with-channel request channel
    (send! channel (response "hello world"))

Answer 1

handler-one function uses synchronous approach. Request -> Response

handle-two is a way to achieve Request -> Response but asynchronously.

You can check with-channel macro definition for more implementation details (and documentation).

If you want more details about asynchronous approach in general, then I recommend learning about one of: Futures, Reactive Programming, Netty, Node.js or Vert.x

Answer 2

Following the theory of core.async channels, if you use channels you will have non-blocking communication meaning that your thread will not be blocked until the http response. If you use the blocking communication waiting for the map http-response your thread will be blocked