code: /**
   * This file is part of Eclipse Steady.
   *
   * 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
   * SPDX-FileCopyrightText: Copyright (c) 2018-2020 SAP SE or an SAP affiliate company and Eclipse Steady contributors
   */
  package org.eclipse.steady.shared.cache;
  
  /**
   * Used to fetch objects from a remote backing store.
   *
   * @param <S> key type
   * @param <T> value type
   */
  public interface ObjectFetcher<S, T> {
  
    /**
     * This method is called by {@link Cache#get(Object)} in case of a cache miss
     * for the given key. The method must be implemented in order to fetch the
     * object with the given key from the (remote) backing store.
     *
     * @param _key a key.
     * @throws org.eclipse.steady.shared.cache.CacheException if fetching fails.
     * @return a value.
     */
    public T fetch(S _key) throws CacheException;
  }
  