--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/implab/messaging/Listener.js	Thu Jun 01 13:20:03 2017 +0300
@@ -0,0 +1,64 @@
+define([ "dojo/_base/declare", "dojo/_base/lang", "./Client" ],
+
+function(declare, lang, Client) {
+    return declare([ Client ], {
+        _listener : null,
+
+        constructor : function(session, destination, options) {
+            if (!options || !options.listener)
+                throw new Error("A listener is required");
+            this._listener = options.listener;
+            if (options.transform)
+                this._transform = options.transform;
+        },
+
+        getMode : function() {
+            return "listener";
+        },
+
+        process : function(result) {
+            switch (result.type) {
+            case "message":
+                try {
+                    this._handleMessage(result.message);
+                } catch (ex) {
+                    var err = new Error("Failed to handle message");
+                    err.envelope = result.message;
+                    err.innerException = ex;
+                    this._handleError(err);
+                }
+                break;
+            case "error":
+                this._handleError(result.error);
+                break;
+            }
+
+        },
+
+        _transform : function(envelope) {
+            return envelope;
+        },
+
+        _handleMessage : function(envelope) {
+            this.log(
+                "MESSAGE type = ${0}, headers = ${2}: ${1}",
+                envelope.bodyType,
+                envelope.body,
+                JSON.stringify(envelope.headers));
+            var data = this._transform(envelope);
+            this._listener(data);
+            this.emit("message", data);
+        },
+
+        _handleError : function(ex) {
+            if (ex.innerException)
+                this.error(
+                    "ERROR: ${0} -> ${1}",
+                    ex.message,
+                    ex.innerException.message);
+            else
+                this.error("ERROR: ${0}", ex.message);
+            this.emit("error", ex);
+        }
+    });
+});
\ No newline at end of file