2 * ============LICENSE_START=======================================================
3 * Copyright (C) 2019 Nordix Foundation.
4 * ================================================================================
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
17 * SPDX-License-Identifier: Apache-2.0
18 * ============LICENSE_END=========================================================
21 package org.onap.policy.models.base;
24 import java.util.concurrent.ConcurrentHashMap;
27 * The model service makes Policy Framework models available to all classes in a JVM.
29 * <p>The reason for having a model service is to avoid having to pass concept and model definitions
30 * down long call chains in modules such as the Policy Framework engine and editor. The model
31 * service makes the model and concept definitions available statically.
33 * <p>Note that the use of the model service means that only a single Policy Framework model of a
34 * particular type may exist in Policy Framework (particularly the engine) at any time. Of course
35 * the model in a JVM can be changed at any time provided all users of the model are stopped and
36 * restarted in an orderly manner.
38 public abstract class PfModelService {
39 // The map holding the models
40 private static Map<Class<?>, PfConcept> modelMap = new ConcurrentHashMap<>();
43 * This class is an abstract static class that cannot be extended.
45 private PfModelService() {}
48 * Register a model with the model service.
50 * @param <M> the generic type
51 * @param modelClass the class of the model, used to index the model
52 * @param model The model
54 public static <M extends PfConcept> void registerModel(final Class<M> modelClass, final M model) {
55 modelMap.put(modelClass, model);
59 * Remove a model from the model service.
61 * @param <M> the generic type
62 * @param modelClass the class of the model, used to index the model
64 public static <M extends PfConcept> void deregisterModel(final Class<M> modelClass) {
65 modelMap.remove(modelClass);
69 * Get a model from the model service.
71 * @param <M> the generic type
72 * @param modelClass the class of the model, used to index the model
75 @SuppressWarnings("unchecked")
76 public static <M extends PfConcept> M getModel(final Class<M> modelClass) {
77 final M model = (M) modelMap.get(modelClass);
80 throw new PfModelRuntimeException(
81 "Model for " + modelClass.getCanonicalName() + " not found in model service");
88 * Check if a model is defined on the model service.
90 * @param <M> the generic type
91 * @param modelClass the class of the model, used to index the model
92 * @return true if the model is defined
94 public static <M extends PfConcept> boolean existsModel(final Class<M> modelClass) {
95 return modelMap.get(modelClass) != null;
99 * Clear all models in the model service.
101 public static void clear() {