Async

[metosin/compojure-api "2.0.0-alpha2"]

Compojure-api supports the new async ring.

See Async example project.

Async handlers & middleware

• Endpoints can return either manifold Deferred or core.async ManyToManyChannels.
• Endpoints and Middleware can be invoked with CPS-style enabling custom async.

(require '[compojure.api.sweet :refer [GET]])
(require '[ring.util.http-response :refer [ok]])
(require '[manifold.deferred :as d])
(require '[aleph.http :as http])
(require '[schema.core :as s])

(def route
  (GET "/repository/:group/:artifact/downloads" []
    :summary "Async gets the clojars download count"
    :path-params [group :- s/Str, artifact :- s/Str]
    :return (s/maybe s/Int)
    (d/chain
      (http/get
        (str "https://clojars.org/api/artifacts/" group "/" artifact)
        {:as :json, :throw-exceptions false})
      :body
      :downloads
      ok)))

;; sync
(route {:request-method :get, :uri "/repository/metosin/compojure-api/downloads"})
; {:body 207917 :headers {} :status 200 :compojure.api.meta/serializable? true}

;; async
(let [respond (promise)
      raise (promise)]
  (route {:request-method :get, :uri "/repository/metosin/compojure-api/downloads"} respond raise)
  (deref respond 2000 ::timeout))
; {:body 207917 :headers {} :status 200 :compojure.api.meta/serializable? true}

Streaming Responses

TODO

Adapters

Ring-adapters (for different web-servers) need to support the async ring. Here's a list of adapters supporting that currently:

• ring-jetty

Should work, need manual bootstrapping:

• Aleph
• HttpKit
• Immutant