--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/prevayler/PrevalentSystem.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,68 @@
+/*
+  The copyright of all source code included in this Prevayler distribution is
+  held by Klaus Wuestefeld, except the files that specifically state otherwise.
+  All rights are reserved. "PREVAYLER" is a trademark of Klaus Wuestefeld.
+
+
+  BSD License:
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+  - Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+  - Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+ 
+  - Neither the name of Prevayler nor the names of its contributors may be used
+  to endorse or promote products derived from this software without specific
+  prior written permission.
+
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+  POSSIBILITY OF SUCH DAMAGE.
+*/
+
+package org.prevayler;
+
+import java.io.Serializable;
+
+
+/**
+ * A system that implements this interface can be made transparently persistent with Prevayler. All business objects in this system must be deterministic. i.e.: Any two PrevalentSystems of the same class must produce the same results given the same commands.
+ * @see org.prevayler.Prevayler
+ */
+public interface PrevalentSystem extends Serializable {
+
+  /**
+   * Sets the clock to be used by this system for ALL its date/time related functions. This method is called only once by Prevayler during the first system initialization.
+   */
+  public void clock(AlarmClock clock);
+
+  /**
+   * Returns the clock used by this system for ALL its date/time related functions.
+   */
+  public AlarmClock clock();
+
+    public void add(SnapshotContributor aContributor);
+
+    /**
+       This method would typically be used, for example, when something is
+       about to be deleted or freed (perhaps as part of delete all Entry's)
+       and thus doesn't wish to provide contributions any longer
+     */
+    public void remove(SnapshotContributor aContributor);
+
+    public Serializable[] getSnapshotContributions();
+}