core/api/src/main/java/org/onosproject/store/cluster/messaging/MessagingService.java

/*
 * Copyright 2015-present Open Networking Foundation
 *
 * 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.
 */
package org.onosproject.store.cluster.messaging;

import java.time.Duration;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;

import com.google.common.util.concurrent.MoreExecutors;

/**
 * Interface for low level messaging primitives.
 */
public interface MessagingService {

    /**
     * Sends a message asynchronously to the specified communication end point.
     * The message is specified using the type and payload.
     * @param ep end point to send the message to.
     * @param type type of message.
     * @param payload message payload bytes.
     * @return future that is completed when the message is sent
     */
    CompletableFuture<Void> sendAsync(Endpoint ep, String type, byte[] payload);

    /**
     * Sends a message asynchronously and expects a response.
     * @param ep end point to send the message to.
     * @param type type of message.
     * @param payload message payload.
     * @return a response future
     */
    default CompletableFuture<byte[]> sendAndReceive(Endpoint ep, String type, byte[] payload) {
        return sendAndReceive(ep, type, payload, null, MoreExecutors.directExecutor());
    }

    /**
     * Sends a message synchronously and expects a response.
     * @param ep end point to send the message to.
     * @param type type of message.
     * @param payload message payload.
     * @param executor executor over which any follow up actions after completion will be executed.
     * @return a response future
     */
    default CompletableFuture<byte[]> sendAndReceive(Endpoint ep, String type, byte[] payload, Executor executor) {
        return sendAndReceive(ep, type, payload, null, executor);
    }

    /**
     * Sends a message asynchronously and expects a response.
     * @param ep end point to send the message to.
     * @param type type of message.
     * @param payload message payload.
     * @param timeout operation timeout
     * @return a response future
     */
    default CompletableFuture<byte[]> sendAndReceive(Endpoint ep, String type, byte[] payload, Duration timeout) {
        return sendAndReceive(ep, type, payload, timeout, MoreExecutors.directExecutor());
    }

    /**
     * Sends a message synchronously and expects a response.
     * @param ep end point to send the message to.
     * @param type type of message.
     * @param payload message payload.
     * @param executor executor over which any follow up actions after completion will be executed.
     * @param timeout operation timeout
     * @return a response future
     */
    CompletableFuture<byte[]> sendAndReceive(Endpoint ep, String type, byte[] payload, Duration timeout,
                                             Executor executor);

    /**
     * Registers a new message handler for message type.
     * @param type message type.
     * @param handler message handler
     * @param executor executor to use for running message handler logic.
     */
    void registerHandler(String type, BiConsumer<Endpoint, byte[]> handler, Executor executor);

    /**
     * Registers a new message handler for message type.
     * @param type message type.
     * @param handler message handler
     * @param executor executor to use for running message handler logic.
     */
    void registerHandler(String type, BiFunction<Endpoint, byte[], byte[]> handler, Executor executor);

    /**
     * Registers a new message handler for message type.
     * @param type message type.
     * @param handler message handler
     */
    void registerHandler(String type, BiFunction<Endpoint, byte[], CompletableFuture<byte[]>> handler);

    /**
     * Unregister current handler, if one exists for message type.
     * @param type message type
     */
    void unregisterHandler(String type);
}