[ONOS-7054] Implement prototype of ISSU protocol
Change-Id: Id543c0de9c97b68f977c824cbc987b35d81beb2d
diff --git a/core/api/src/main/java/org/onosproject/upgrade/UpgradeService.java b/core/api/src/main/java/org/onosproject/upgrade/UpgradeService.java
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+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * 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.upgrade;
+
+import com.google.common.annotations.Beta;
+import org.onosproject.core.Version;
+import org.onosproject.event.ListenerService;
+
+/**
+ * Upgrade service.
+ */
+@Beta
+public interface UpgradeService
+ extends ListenerService<UpgradeEvent, UpgradeEventListener> {
+
+ /**
+ * Returns whether an upgrade is in progress.
+ * <p>
+ * An upgrade is in progress if the upgrade {@link Upgrade.Status} is active, e.g.
+ * {@link Upgrade.Status#INITIALIZED}, {@link Upgrade.Status#UPGRADED}, etc.
+ *
+ * @return indicates whether an upgrade is in progress
+ */
+ boolean isUpgrading();
+
+ /**
+ * Returns the current upgrade state.
+ *
+ * @return the current upgrade state
+ */
+ Upgrade getState();
+
+ /**
+ * Returns the currently active software version.
+ * <p>
+ * The returned version is representative of the version currently in control of the network. When the upgrade
+ * transitions to the {@link Upgrade.Status#UPGRADING} state, control over the network is transferred from
+ * {@link Upgrade#source()} nodes to {@link Upgrade#target()} nodes, and the version returned by this method
+ * represents that change.
+ *
+ * @return the software version
+ */
+ Version getVersion();
+
+ /**
+ * Returns whether the local node is active.
+ * <p>
+ * The local node will be active if its {@link Version} matches the version returned by {@link #getVersion()}.
+ *
+ * @return indicates whether the local node is active according to its version
+ */
+ boolean isLocalActive();
+
+ /**
+ * Returns whether the local node is an upgraded node.
+ *
+ * @return {@code true} if the local node's version matches {@link Upgrade#target()}
+ */
+ boolean isLocalUpgraded();
+
+}