1 files changed, 51 insertions, 0 deletions
diff --git a/spss.server/src/at/gv/egovernment/moa/spss/server/transaction/TransactionIDGenerator.java b/spss.server/src/at/gv/egovernment/moa/spss/server/transaction/TransactionIDGenerator.java
new file mode 100644
index 000000000..6eb07defe
--- /dev/null
+++ b/spss.server/src/at/gv/egovernment/moa/spss/server/transaction/TransactionIDGenerator.java
@@ -0,0 +1,51 @@
+package at.gv.egovernment.moa.spss.server.transaction;
+
+
+/**
+ * A generator for unique transaction IDs.
+ * 
+ * <p>The transaction IDs are of the form "<base>-<counter>", where:
+ * <ul> 
+ * <li><code>base</code> is initialized with the system time when this class is
+ * being loaded</li>
+ * <li><code>counter</code> is incremented sequentially on each call to
+ * <code>nextID()</code></li>
+ * </ul>
+ * </p>
+ * 
+ * <p> Assuming that it is highly unlikely that MOA servers are started at
+ * exactly the same time instant, the mechanism provided by this class should
+ * guarantee unique transaction IDs across multiple restarts and/or instances of
+ * the server.</p>
+ * 
+ * @author Patrick Peck
+ * @author Stefan Knirsch
+ */
+public class TransactionIDGenerator {
+
+  /** Request sequence number. */
+  private static long counter = 0;
+  /** The base value to which to append the sequence number. */
+  private static String base = null;
+
+  /**
+   * Set up the initial base value.
+   */
+  static {
+    synchronized (TransactionIDGenerator.class) {
+      base = Long.toString(System.currentTimeMillis());
+    }
+  }
+
+  /**
+   * Returns the next transaction ID.
+   * 
+   * @return The next transaction ID.
+   */
+  public static synchronized String nextID() {
+    counter++;
+
+    return (base + "-" + counter);
+  }
+
+}