diff --git a/src/main/java/org/bdware/sc/boundry/JavaScriptEntry.java b/src/main/java/org/bdware/sc/boundry/JavaScriptEntry.java
index b436616..5a52252 100644
--- a/src/main/java/org/bdware/sc/boundry/JavaScriptEntry.java
+++ b/src/main/java/org/bdware/sc/boundry/JavaScriptEntry.java
@@ -586,12 +586,13 @@ public class JavaScriptEntry {
      * @param fun   related handler function
      * @author Kaidong Wu
      */
-    public static void subscribe(String topic, ScriptFunction fun) {
+    public static String subscribe(String topic, ScriptFunction fun) {
         subscribe(topic, fun, false);
         if (topic_handlers.containsKey(topic)) {
             ContractProcess.instance.unSubscribe(topic_handlers.get(topic).getName());
         }
         topic_handlers.put(topic, fun);
+        return topic;
     }
 
     /**
@@ -602,13 +603,14 @@ public class JavaScriptEntry {
      * @param fun        related handler function
      * @author Kaidong Wu
      */
-    public static void subscribe(String contractID, String event, ScriptFunction fun) {
+    public static String subscribe(String contractID, String event, ScriptFunction fun) {
         String topic = HashUtil.sha3(contractID, event);
         subscribe(topic, fun, false);
         if (topic_handlers.containsKey(topic)) {
             ContractProcess.instance.unSubscribe(topic_handlers.get(topic).getName());
         }
         topic_handlers.put(topic, fun);
+        return topic;
     }
 
     private static void subscribe(String topic, ScriptFunction fun, boolean fromPreSub) {