diff --git a/src/morevna.py b/src/morevna.py
--- a/src/morevna.py
+++ b/src/morevna.py
@@ -3,22 +3,41 @@ import os.path
 from argparse import ArgumentParser
 
 from hashtree import HashTree
+from client import Client
+from server import Server
+
+
+def _checkDatafile(datafile):
+	if not os.path.isfile(datafile):
+		print("invalid file specified:",args.datafile,file=sys.stderr)
+		sys.exit(1)
 
 
 def buildTree(args):
-	if not os.path.isfile(args.datafile):
-		print("invalid file specified:",args.datafile,file=sys.stderr)
-		return
+	_checkDatafile(args.datafile)
+
 	tree=HashTree.fromFile(args.datafile)
 	tree.save(args.treefile)
 
 def update(args):
-	print("ready to update")
-	print(args)
+	_checkDatafile(args.datafile)
+
+	c=Client(args.datafile)
+	blocksToTransfer=c.negotiate()
+	c.sendData(blocksToTransfer)
 
 def serve(args):
-	print("ready to serve")
-	print(args)
+	_checkDatafile(args.datafile)
+
+	# debug copy default file
+	import shutil
+	origFilename=args.datafile
+	filename=origFilename+"_"
+	shutil.copyfile(origFilename,filename)
+
+	s=Server(filename)
+	s.serve()
+
 
 parser=ArgumentParser()
 subparsers=parser.add_subparsers()