diff --git a/src/wormhole/twisted/demo.py b/src/wormhole/twisted/demo.py
index adc3b74..a9313d6 100644
--- a/src/wormhole/twisted/demo.py
+++ b/src/wormhole/twisted/demo.py
@@ -1,28 +1,38 @@
-import sys
+import sys, json
 from twisted.internet import reactor
-from .transcribe import SymmetricWormhole
+from .transcribe import Wormhole
 from .. import public_relay
 
 APPID = "lothar.com/wormhole/text-xfer"
 
-w = SymmetricWormhole(APPID, public_relay.RENDEZVOUS_RELAY)
+w = Wormhole(APPID, public_relay.RENDEZVOUS_RELAY)
 
 if sys.argv[1] == "send-text":
     message = sys.argv[2]
+    data = json.dumps({"message": message}).encode("utf-8")
     d = w.get_code()
     def _got_code(code):
         print "code is:", code
-        return w.get_data(message)
+        return w.get_data(data)
     d.addCallback(_got_code)
-    def _got_data(their_data):
-        print "ack:", their_data
+    def _got_data(them_bytes):
+        them_d = json.loads(them_bytes.decode("utf-8"))
+        if them_d["message"] == "ok":
+            print "text sent"
+        else:
+            print "error sending text: %r" % (them_d,)
     d.addCallback(_got_data)
 elif sys.argv[1] == "receive-text":
     code = sys.argv[2]
     w.set_code(code)
-    d = w.get_data("ok")
-    def _got_data(their_data):
-        print their_data
+    data = json.dumps({"message": "ok"}).encode("utf-8")
+    d = w.get_data(data)
+    def _got_data(them_bytes):
+        them_d = json.loads(them_bytes.decode("utf-8"))
+        if "error" in them_d:
+            print >>sys.stderr, "ERROR: " + them_d["error"]
+            return 1
+        print them_d["message"]
     d.addCallback(_got_data)
 else:
     raise ValueError("bad command")