/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.kafka.streams.state;
import org.apache.kafka.common.annotation.InterfaceStability;
import org.apache.kafka.streams.kstream.Windowed;
/**
* A session store that only supports read operations.
* Implementations should be thread-safe as concurrent reads and writes
* are expected.
*
* @param <K> the key type
* @param <AGG> the aggregated value type
*/
@InterfaceStability.Unstable
public interface ReadOnlySessionStore<K, AGG> {
/**
* Retrieve all aggregated sessions for the provided key
*
* For each key, the iterator guarantees ordering of sessions, starting from the oldest/earliest
* available session to the newest/latest session.
*
* @param key record key to find aggregated session values for
* @return KeyValueIterator containing all sessions for the provided key.
*/
KeyValueIterator<Windowed<K>, AGG> fetch(final K key);
}