--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/dancres/blitz/notify/QueueEvent.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,109 @@
+package org.dancres.blitz.notify;
+
+import org.dancres.blitz.txn.TxnState;
+import org.dancres.blitz.mangler.MangledEntry;
+import org.dancres.blitz.oid.OID;
+
+/**
+   <p>The event types break down into two classes - those that represent
+   an invisible/visible transition and those that represent an
+   unavailable/available transition.  Here's a summary in table form:</p>
+
+<table summary="Visibility and Availability Transitions" border="0" cellspacing="2" cellpadding="1">
+<tr align="center" valign="middle"><th></th><th>Invisible/Visible</th><th>Unavailable/Available</th>
+</tr>
+<tr align="center" valign="middle"><th>ENTRY_WRITE</th>
+	<td>X</td>
+	<td>X</td>
+</tr>
+<tr align="center" valign="middle"><th>ENTRY_WRITTEN</th>
+	<td>X</td>
+	<td>X</td>
+</tr>
+<tr align="center" valign="middle"><th>ENTRY_VISIBLE</th>
+	<td>X</td>
+	<td>X</td>
+</tr>
+<tr align="center" valign="middle"><th>ENTRY_NOT_CONFLICTED</th>
+	<td>O</td>
+	<td>X</td>
+</tr>
+</table>
+
+   @see org.dancres.blitz.notify.EventQueue
+ */
+public class QueueEvent {
+    /**
+       Context object is null
+     */
+    public static final int TRANSACTION_ENDED = 1;
+
+    /**
+       Context object is a MangledEntry plus OID -
+       this event is triggered when a transaction initially writes a new Entry
+     */
+    public static final int ENTRY_WRITE = 2;
+
+    /**
+       Context object is a MangledEntry plus OID -
+       this event is triggered when a transaction commits a write.
+     */
+    public static final int ENTRY_WRITTEN = 3;
+
+    /**
+       Context object is a MangledEntry plus OID - this event is triggered in
+       the case where a take has been aborted and thus an Entry has been deemed
+       visible again.
+     */
+    public static final int ENTRY_VISIBLE = 4;
+
+    /**
+       Context object is a MangledEntry plus OID - this event is triggered in
+       the case where an Entry was previously conflicted with a collection of
+       read locks and has since been made available for a take again.
+       Note, if the Entry was write locked, we don't generate this event
+       as it'll result from the ENTRY_WRITTEN event.  Note also we don't
+       generate this event if the Entry is marked as taken/deleted (obviously)
+     */
+    public static final int ENTRY_NOT_CONFLICTED = 5;
+
+    private int theType;
+    private TxnState theTxn;
+    private Context theContext;
+
+    public QueueEvent(int aType, TxnState aTxn, Context aContext) {
+        theType = aType;
+        theTxn = aTxn;
+        theContext = aContext;
+    }
+
+    public int getType() {
+        return theType;
+    }
+
+    public TxnState getTxn() {
+        return theTxn;
+    }
+
+    public Context getContext() {
+        return theContext;
+    }
+
+    public static class Context {
+        private MangledEntry _entry;
+        private OID _oid;
+
+        public Context(MangledEntry anEntry, OID anOID) {
+            _oid = anOID;
+            _entry = anEntry;
+        }
+
+        public MangledEntry getEntry() {
+            return _entry;
+        }
+
+        public OID getOID() {
+            return _oid;
+        }
+    }
+}