/**
 * 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;
}
