1 files changed, 5 insertions, 0 deletions

diff --git a/include/opkele/types.h b/include/opkele/types.h
index 757c0af..8f4bf73 100644
--- a/include/opkele/types.h
+++ b/include/opkele/types.h
@@ -95,6 +95,11 @@ namespace opkele {
              * @return true if stateless
              */
             virtual bool stateless() const = 0;
+            /**
+             * check whether the association is expired.
+             * @return true if expired
+             */
+            virtual bool is_expired() const = 0;
     };
 
     /**