--- a/Implab/ActionChainTaskBase.cs	Wed Apr 15 07:30:20 2015 +0300
+++ b/Implab/ActionChainTaskBase.cs	Wed May 06 17:11:27 2015 +0300
@@ -8,9 +8,11 @@
 
         int m_cancelationLock;
 
-        protected ActionChainTaskBase( Func<Exception, IPromise> error, Func<Exception, IPromise> cancel) {
+        protected ActionChainTaskBase(Func<Exception, IPromise> error, Func<Exception, IPromise> cancel, bool autoCancellable) {
             m_error = error;
             m_cancel = cancel;
+            if (autoCancellable)
+                CancellationRequested(CancelOperation);
         }
 
         public void Reject(Exception error) {
@@ -21,21 +23,26 @@
 
 
         public override void CancelOperation(Exception reason) {
-            if (m_cancel != null && LockCancelation()) {
-                try {
-                    Observe(m_cancel(reason));
-                } catch(Exception err) {
-                    HandleErrorInternal(err);
+            if (LockCancelation()) {
+                if (m_cancel != null) {
+                    try {
+                        m_cancel(reason).On(SetResult, SetError, SetCancelled);
+                    } catch (Exception err) {
+                        HandleErrorInternal(err);
+                    }
+                } else {
+                    SetCancelled(reason);
                 }
             }
-
         }
 
         protected void HandleErrorInternal(Exception error) {
             if (m_error != null) {
                 try {
-                    Observe(m_error(error));
-                } catch(Exception err) {
+                    var p = m_error(error);
+                    p.On(SetResult,SetError,SetCancelled);
+                    CancellationRequested(p.Cancel);
+                } catch (Exception err) {
                     SetError(err);
                 }
             } else {
@@ -43,17 +50,6 @@
             }
         }
 
-        protected void Observe(IPromise operation) {
-            if (operation == null)
-                throw new NullReferenceException("The task returned null promise");
-
-            // pass operation results to the current promise
-            operation.On(SetResult, SetError, SetCancelled);
-
-            // pass the cancelation request
-            CancellationRequested(operation.Cancel);
-        }
-
         protected bool LockCancelation() {
             return 0 == Interlocked.CompareExchange(ref m_cancelationLock, 1, 0);
         }