1 files changed, 110 insertions, 0 deletions
diff --git a/common/src/main/java/org/onap/policy/clamp/controlloop/common/handler/ControlLoopHandler.java b/common/src/main/java/org/onap/policy/clamp/controlloop/common/handler/ControlLoopHandler.java
new file mode 100644
index 000000000..1bbe5662f
--- /dev/null
+++ b/common/src/main/java/org/onap/policy/clamp/controlloop/common/handler/ControlLoopHandler.java
@@ -0,0 +1,110 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * Copyright (C) 2021 Nordix 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.clamp.controlloop.common.handler;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import lombok.Getter;
+import lombok.NonNull;
+import org.onap.policy.common.endpoints.event.comm.TopicSink;
+import org.onap.policy.common.endpoints.listeners.MessageTypeDispatcher;
+import org.onap.policy.common.utils.services.Registry;
+import org.onap.policy.models.provider.PolicyModelsProviderParameters;
+
+/**
+ * Abstract class for handlers for sub components in the control loop system
+ *
+ * <p>Instances are effectively singletons that are started at system start.
+ */
+public abstract class ControlLoopHandler {
+    @Getter
+    private final PolicyModelsProviderParameters databaseProviderParameters;
+
+    /**
+     * Create a handler.
+     *
+     * @param databaseProviderParameters the parameters for access to the database
+     */
+    protected ControlLoopHandler(@NonNull PolicyModelsProviderParameters databaseProviderParameters) {
+        this.databaseProviderParameters = databaseProviderParameters;
+
+        Registry.register(this.getClass().getName(), this);
+    }
+
+    public void close() {
+        Registry.unregister(this.getClass().getName());
+    }
+
+    /**
+     * Get the provider classes that are used in instantiation.
+     *
+     * @return the provider classes
+     */
+    public Set<Class<?>> getProviderClasses() {
+        // No REST interfaces are the default
+        return new HashSet<>();
+    }
+
+    /**
+     * Start any topic message listeners for this handler.
+     *
+     * @param msgDispatcher the message dispatcher with which to register the listener
+     */
+    public void startAndRegisterListeners(MessageTypeDispatcher msgDispatcher) {
+        // Start and register listeners
+    }
+
+    /**
+     * Start any topic message publishers for this handler.
+     *
+     * @param topicSinks the topic sinks on which the publisher can publish
+     */
+    public void startAndRegisterPublishers(List<TopicSink> topicSinks) {
+        // Start and register publishers
+    }
+
+    /**
+     * Stop any topic message publishers for this handler.
+     */
+    public void stopAndUnregisterPublishers() {
+        // Stop and unregister publishers
+    }
+
+    /**
+     * Stop any topic message listeners for this handler.
+     *
+     * @param msgDispatcher the message dispatcher from which to unregister the listener
+     */
+    public void stopAndUnregisterListeners(MessageTypeDispatcher msgDispatcher) {
+        // Stop and unregister listeners
+    }
+
+    /**
+     * Start any providers for this handler.
+     */
+    public abstract void startProviders();
+
+    /**
+     * Stop any providers for this handler.
+     */
+    public abstract void stopProviders();
+}