Preliminary support for Server-Sent Events [IMMUTANT-439]

web/src/immutant/web/sse.clj

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+;; Copyright 2014-2015 Red Hat, Inc, and individual contributors.
+;;
+;; Licensed under the Apache License, Version 2.0 (the "License");
+;; you may not use this file except in compliance with the License.
+;; You may obtain a copy of the License at
+;;
+;; http://www.apache.org/licenses/LICENSE-2.0
+;;
+;; Unless required by applicable law or agreed to in writing, software
+;; distributed under the License is distributed on an "AS IS" BASIS,
+;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;; See the License for the specific language governing permissions and
+;; limitations under the License.
+
+(ns immutant.web.sse
+  "Provides Server-Sent Events via [[immutant.web.async/as-channel]]"
+  (:require [immutant.web.async :as async]))
+
+(defn with-event-type [m]
+  (update-in m [:headers] assoc "Content-Type" "text/event-stream; charset=utf-8"))
+
+(def as-sse-channel (comp with-event-type async/as-channel))
+
+(defprotocol Event
+  (event->str [x] "Formats event according to SSE spec"))
+
+(extend-protocol Event
+  Object
+  (event->str [o] (str "data:" o "\n"))
+  java.util.Collection
+  (event->str [c] (apply str (map event->str c)))
+  java.util.Map
+  (event->str [m] (apply str
+                (-> (for [[k v] (dissoc m :data)]
+                      (format "%s:%s\n" (name k) v))
+                  (conj (event->str (:data m)))))))
+
+(defn send!
+  [ch event]
+  (async/send! ch (str (event->str event) "\n")))

web/test/immutant/web/sse_test.clj

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+;; Copyright 2014-2015 Red Hat, Inc, and individual contributors.
+;;
+;; Licensed under the Apache License, Version 2.0 (the "License");
+;; you may not use this file except in compliance with the License.
+;; You may obtain a copy of the License at
+;;
+;; http://www.apache.org/licenses/LICENSE-2.0
+;;
+;; Unless required by applicable law or agreed to in writing, software
+;; distributed under the License is distributed on an "AS IS" BASIS,
+;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;; See the License for the specific language governing permissions and
+;; limitations under the License.
+
+(ns immutant.web.sse-test
+  (:require [clojure.test :refer :all]
+            [immutant.web.sse :refer :all]
+            [clojure.string :refer (split-lines)]))
+
+(deftest format-string
+  (is (= "data:foo\n"
+        (event->str "foo"))))
+
+(deftest format-collection
+  (is (= "data:0\ndata:1\ndata:2\n"
+        (event->str [0 1 2])
+        (event->str (range 3))
+        (event->str '("0" "1" "2")))))
+
+(deftest format-map
+  (let [result (event->str {:data "foo", :event "bar", :id 42, :retry 1000})
+        sorted (sort (split-lines result))]
+    (is (.endsWith result "\n"))
+    (is (= ["data:foo" "event:bar" "id:42" "retry:1000"] sorted))))
+
+(deftest format-collection-in-map
+  (is (= "data:0\ndata:1\ndata:2\n"
+        (event->str {:data (range 3)}))))