WIP: Revamped transaction API. Introduces a transaction context for running blocks of code that can be committed
atomically.

Change-Id: I6ba21050a2644a42f3c073fa04ff776ef2c5ff4c
diff --git a/core/api/src/main/java/org/onosproject/store/service/TransactionException.java b/core/api/src/main/java/org/onosproject/store/service/TransactionException.java
new file mode 100644
index 0000000..8261fbd
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/service/TransactionException.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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 org.onosproject.store.service;
+
+/**
+ * Top level exception for Transaction failures.
+ */
+@SuppressWarnings("serial")
+public class TransactionException extends RuntimeException {
+    public TransactionException() {
+    }
+
+    public TransactionException(Throwable t) {
+        super(t);
+    }
+
+    /**
+     * Transaction timeout.
+     */
+    public static class Timeout extends TransactionException {
+    }
+
+    /**
+     * Transaction interrupted.
+     */
+    public static class Interrupted extends TransactionException {
+    }
+
+    /**
+     * Transaction failure due to optimistic concurrency failure.
+     */
+    public static class OptimisticConcurrencyFailure extends TransactionException {
+    }
+}
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