/*
 * 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.dubbo.common.stream;

/**
 * StreamObserver is a common streaming API. It is an observer for receiving messages.
 * Implementations are NOT required to be thread-safe.
 *
 * @param <T> type of message
 */
public interface StreamObserver<T> {

    /**
     * onNext
     *
     * @param data to process
     */
    void onNext(T data);

    /**
     * onError
     *
     * @param throwable error
     */
    void onError(Throwable throwable);

    /**
     * onCompleted
     */
    void onCompleted();
}
