1 files changed, 66 insertions, 0 deletions
diff --git a/spss/server/serverlib/src/main/java/at/gv/egovernment/moa/spss/server/transaction/TransactionIDGenerator.java b/spss/server/serverlib/src/main/java/at/gv/egovernment/moa/spss/server/transaction/TransactionIDGenerator.java
new file mode 100644
index 000000000..715eb1e52
--- /dev/null
+++ b/spss/server/serverlib/src/main/java/at/gv/egovernment/moa/spss/server/transaction/TransactionIDGenerator.java
@@ -0,0 +1,66 @@
+/*
+* Copyright 2003 Federal Chancellery Austria
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*     http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+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);
+  }
+
+}