Add Clojure RPC tutorial code.

Author: Ferada

clojure/README.md

@@ -40,6 +40,7 @@ Code examples are executed via `lein run`:
 
 [Tutorial six: RPC](http://www.rabbitmq.com/tutorial-six-java.html)
 
-    TBD
+    lein run -m rabbitmq.tutorials.rpc-server
+    lein run -m rabbitmq.tutorials.rpc-client
 
 To learn more, visit [Langohr documentation](http://clojurerabbitmq.info) site.

clojure/src/rabbitmq/tutorials/rpc_client.clj

@@ -0,0 +1,45 @@
+;; note: this is example code and shouldn't be run in production as-is
+
+(ns rabbitmq.tutorials.rpc-client
+  (:require [langohr.core :as lc]
+            [langohr.channel :as lch]
+            [langohr.queue :as lq]
+            [langohr.basic :as lb]
+            [langohr.consumers :as lcons]))
+
+(def ^{:const true} q "rpc_queue")
+
+(defn correlation-id-equals?
+  [correlation-id d]
+  (= (.getCorrelationId (.getProperties d)) correlation-id))
+
+(defrecord FibonacciClient [conn ch cbq consumer]
+  clojure.lang.IFn
+  (invoke [this n]
+    (let [correlation-id (str (java.util.UUID/randomUUID))]
+      (lb/publish ch "" q (str n) {:reply-to cbq
+                                   :correlation-id correlation-id})
+      (lb/consume ch cbq consumer)
+      (-> (first (filter (partial correlation-id-equals? correlation-id)
+                         (lcons/deliveries-seq consumer)))
+          .getBody
+          (String. "UTF-8")
+          (read-string))))
+  java.io.Closeable
+  (close [this]
+    (.close conn)))
+
+(defn make-fibonacci-rpc-client
+  []
+  (let [conn     (lc/connect)
+        ch       (lch/open conn)
+        cbq      (lq/declare ch "" {:auto-delete false :exclusive true})
+        consumer (lcons/create-queueing ch {})]
+    (->FibonacciClient conn ch (:queue cbq) consumer)))
+
+(defn -main
+  [& args]
+  (with-open [fibonacci-rpc (make-fibonacci-rpc-client)]
+    (println " [x] Requesting fib(30)")
+    (let [response (fibonacci-rpc 30)]
+      (println (format " [.] Got %s" response)))))

clojure/src/rabbitmq/tutorials/rpc_server.clj

@@ -0,0 +1,35 @@
+(ns rabbitmq.tutorials.rpc-server
+  (:require [langohr.core :as lc]
+            [langohr.channel :as lch]
+            [langohr.queue :as lq]
+            [langohr.basic :as lb]
+            [langohr.consumers :as lcons]))
+
+(def ^{:const true} q "rpc_queue")
+
+(defn fib
+  [n]
+  (if (zero? n)
+    0
+    (if (= n 1)
+      1
+      (+ (fib (- n 1))
+         (fib (- n 2))))))
+
+(defn handle-delivery
+  "Handles message delivery"
+  [ch {:keys [delivery-tag reply-to correlation-id]} payload]
+  (let [n (read-string (String. payload "UTF-8"))]
+    (println (format " [.] fib(%s)" n))
+    (let [response (fib n)]
+      (lb/publish ch "" reply-to (str response) {:correlation-id correlation-id})
+      (lb/ack ch delivery-tag))))
+
+(defn -main
+  [& args]
+  (with-open [conn (lc/connect)]
+    (let [ch (lch/open conn)]
+      (lq/declare ch q {:auto-delete false})
+      (lb/qos ch 1)
+      (println " [x] Awaiting RPC requests")
+      (lcons/blocking-subscribe ch "rpc_queue" handle-delivery))))