diff --git a/xos/tosca/engine.py b/xos/tosca/engine.py
index a01ddd6..b5ce94b 100644
--- a/xos/tosca/engine.py
+++ b/xos/tosca/engine.py
@@ -28,10 +28,84 @@
         finally:
             os.remove(tmp_pathname)
 
+        self.compute_dependencies()
+
+        self.ordered_nodetemplates = []
+        self.ordered_names = self.topsort_dependencies()
+        for name in self.ordered_names:
+            if name in self.nodetemplates_by_name:
+                self.ordered_nodetemplates.append(self.nodetemplates_by_name[name])
+
         #pdb.set_trace()
 
-    def execute(self, user):
+    def compute_dependencies(self):
+        nodetemplates_by_name = {}
         for nodetemplate in self.template.nodetemplates:
+            nodetemplates_by_name[nodetemplate.name] = nodetemplate
+
+        self.nodetemplates_by_name = nodetemplates_by_name
+
+        for nodetemplate in self.template.nodetemplates:
+            nodetemplate.dependencies = []
+            nodetemplate.dependencies_names = []
+            for reqs in nodetemplate.requirements:
+                for (k,v) in reqs.items():
+                    name = v["node"]
+                    if (name in nodetemplates_by_name):
+                        nodetemplate.dependencies.append(nodetemplates_by_name[name])
+                        nodetemplate.dependencies_names.append(name)
+
+    def topsort_dependencies(self):
+        # stolen from observer
+        g = self.nodetemplates_by_name
+
+	# Get set of all nodes, including those without outgoing edges
+	keys = set(g.keys())
+	values = set({})
+	for v in g.values():
+		values=values | set(v.dependencies_names)
+
+	all_nodes=list(keys|values)
+        steps = all_nodes
+
+	# Final order
+	order = []
+
+	# DFS stack, not using recursion
+	stack = []
+
+	# Unmarked set
+	unmarked = all_nodes
+
+	# visiting = [] - skip, don't expect 1000s of nodes, |E|/|V| is small
+
+	while unmarked:
+		stack.insert(0,unmarked[0]) # push first unmarked
+
+		while (stack):
+			n = stack[0]
+			add = True
+			try:
+				for m in g[n].dependencies_names:
+					if (m in unmarked):
+					    add = False
+					    stack.insert(0,m)
+			except KeyError:
+				pass
+			if (add):
+				if (n in steps and n not in order):
+					order.append(n)
+				item = stack.pop(0)
+				try:
+					unmarked.remove(item)
+				except ValueError:
+					pass
+
+	noorder = list(set(steps) - set(order))
+	return order + noorder
+
+    def execute(self, user):
+        for nodetemplate in self.ordered_nodetemplates: # self.template.nodetemplates:
             self.execute_nodetemplate(user, nodetemplate)
 
     def execute_nodetemplate(self, user, nodetemplate):
@@ -44,13 +118,14 @@
     def execute_nodetemplate(self, user, nodetemplate):
         if nodetemplate.type in resources.resources:
             cls = resources.resources[nodetemplate.type]
-            #print "work on", cls.__name__, nodetemplate.name
+            print "work on", cls.__name__, nodetemplate.name
             obj = cls(user, nodetemplate)
             obj.create_or_update()
 
     def destroy(self, user):
+        nodetemplates = self.ordered_nodetemplates
         models = []
-        for nodetemplate in self.template.nodetemplates:
+        for nodetemplate in nodetemplates:
             if nodetemplate.type in resources.resources:
                 cls = resources.resources[nodetemplate.type]
                 obj = cls(user, nodetemplate)