diff --git a/src/main/java/com/eactive/eai/custom/transformer/function/userdefined/SubStringRequestMessage.java b/src/main/java/com/eactive/eai/custom/transformer/function/userdefined/SubStringRequestMessage.java
new file mode 100644
index 0000000..b02b4b5
--- /dev/null
+++ b/src/main/java/com/eactive/eai/custom/transformer/function/userdefined/SubStringRequestMessage.java
@@ -0,0 +1,44 @@
+package com.eactive.eai.custom.transformer.function.userdefined;
+
+import com.eactive.eai.common.context.ElinkTransactionContext;
+import org.apache.commons.lang.StringUtils;
+import org.nfunk.jep.ParseException;
+import org.nfunk.jep.function.PostfixMathCommand;
+
+import java.util.Stack;
+
+public class SubStringRequestMessage  extends PostfixMathCommand {
+    public SubStringRequestMessage() {
+        numberOfParameters = -1;
+    }
+
+    public void run(Stack inStack) throws ParseException {
+        checkStack(inStack);
+
+        String bizData = ElinkTransactionContext.getRequestBizData();
+
+        Object p1 = inStack.pop();
+        Object p2 = inStack.pop();
+
+        int start = toInt(p2);
+        int end = toInt(p1);
+
+        String resultStr = bizData.substring(start, end);
+
+        if(inStack.size() > 0){
+            inStack.pop();
+        }
+
+        inStack.push(resultStr);
+    }
+
+    public static int toInt(Object obj) {
+        if (obj instanceof Number) {
+            return ((Number) obj).intValue();
+        }
+        if (obj instanceof String) {
+            return Integer.parseInt(((String) obj).trim());
+        }
+        throw new IllegalArgumentException("Cannot convert to int: " + obj);
+    }
+}