Revert "[mod] [taoensso#424] [BREAKING] Temporarily remove `jetty9-ri…

…ng-adapter` support"

This reverts commit c3d7c6c.

src/taoensso/sente/server_adapters/jetty9.clj

@@ -0,0 +1,51 @@
+(ns taoensso.sente.server-adapters.jetty9
+  "Sente adapter for ring-jetty9-adapter,
+  (https://github.com/sunng87/ring-jetty9-adapter).
+
+  Note that ring-jetty9-adapter defines WebSocket routes/handlers
+  separately from regular Ring routes/handlers [1,2].
+
+  This can make it tricky to set up stateful middleware correctly
+  (for example as you may want to do for CSRF protection).
+
+  See [3] for a full example.
+
+  [1] https://github.com/sunng87/ring-jetty9-adapter/blob/master/examples/rj9a/websocket.clj
+  [2] https://github.com/sunng87/ring-jetty9-adapter/issues/41#issuecomment-630206233
+  [3] https://gist.github.com/wavejumper/40c4cbb21d67e4415e20685710b68ea0"
+
+  {:author "Thomas Crowley (@wavejumper)"}
+  (:require [clojure.string :as str]
+            [ring.adapter.jetty9.websocket :as jetty9.websocket]
+            [taoensso.sente.interfaces :as i]))
+
+(defn- ajax-cbs [sch]
+  {:write-failed  (fn [_throwable] (jetty9.websocket/close! sch))
+   :write-success (fn [          ] (jetty9.websocket/close! sch))})
+
+(extend-type org.eclipse.jetty.websocket.api.WebSocketAdapter
+  i/IServerChan
+  (sch-open?  [sch] (jetty9.websocket/connected? sch))
+  (sch-close! [sch] (jetty9.websocket/close!     sch))
+  (sch-send!  [sch websocket? msg]
+    (if websocket?
+      (jetty9.websocket/send! sch msg)
+      (jetty9.websocket/send! sch msg (ajax-cbs sch)))))
+
+(defn- server-ch-resp
+  [websocket? {:keys [on-open on-close on-msg on-error]}]
+  {:on-connect (fn [sch         ] (on-open  sch websocket?))
+   :on-text    (fn [sch msg     ] (on-msg   sch websocket? msg))
+   :on-error   (fn [sch error   ] (on-error sch websocket? error))
+   :on-close   (fn [sch status _] (on-close sch websocket? status))})
+
+(defn- websocket-req? [ring-req]
+  (when-let [s (get-in ring-req [:headers "upgrade"])]
+    (= "websocket" (str/lower-case s))))
+
+(deftype JettyServerChanAdapter []
+  i/IServerChanAdapter
+  (ring-req->server-ch-resp [_ req callbacks-map]
+    (server-ch-resp (websocket-req? req) callbacks-map)))
+
+(defn get-sch-adapter [] (JettyServerChanAdapter.))