diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java
index 65976dc..2ee2764 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java
@@ -1,5 +1,5 @@
 package org.projectfloodlight.openflow.protocol;
 
 public interface XidGenerator {
-    int nextXid();
+    long nextXid();
 }
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerators.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerators.java
new file mode 100644
index 0000000..4609afa
--- /dev/null
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerators.java
@@ -0,0 +1,38 @@
+package org.projectfloodlight.openflow.protocol;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+public class XidGenerators {
+    private static final XidGenerator GLOBAL_XID_GENERATOR = new StandardXidGenerator();
+
+    public static XidGenerator create() {
+        return new StandardXidGenerator();
+    }
+
+    public static XidGenerator global() {
+        return GLOBAL_XID_GENERATOR;
+    }
+}
+
+class StandardXidGenerator implements XidGenerator {
+
+    private final AtomicLong xidGen = new AtomicLong();
+    long MAX_XID = 0xFFffFFffL;
+
+    @Override
+    public long nextXid() {
+        long xid;
+        do {
+            xid = xidGen.incrementAndGet();
+            if(xid > MAX_XID) {
+                synchronized(this) {
+                    if(xidGen.get() > MAX_XID) {
+                        xidGen.set(0);
+                    }
+                }
+            }
+        } while(xid > MAX_XID);
+        return xid;
+    }
+
+}
\ No newline at end of file