org.apache.nifi.remote.client.PeerStatusProvider Maven / Gradle / Ivy
/*
* 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.nifi.remote.client;
import java.io.IOException;
import java.util.Set;
import org.apache.nifi.remote.PeerDescription;
import org.apache.nifi.remote.PeerStatus;
import org.apache.nifi.remote.protocol.SiteToSiteTransportProtocol;
/**
* This interface defines methods used from {@link PeerSelector}.
*/
public interface PeerStatusProvider {
/**
*
* Returns a PeerDescription instance, which represents a bootstrap remote NiFi node.
* The bootstrap node is always used to fetch remote peer statuses.
*
*
* Once the PeerSelector successfully got remote peer statuses, it periodically fetches remote peer statuses,
* so that it can detect remote NiFi cluster topology changes such as addition or removal of nodes.
* To refresh remote peer statuses, PeerSelector calls {@link #fetchRemotePeerStatuses} with one of query-able nodes
* lastly fetched from the remote NiFi cluster, until it gets a successful result,
* or throws IOException if none of them responds successfully.
*
*
* This mechanism lets PeerSelector works even if the bootstrap remote NiFi node goes down.
*
* @return peer description of a bootstrap remote NiFi node
* @throws IOException thrown when it fails to retrieve the bootstrap remote node information
*/
PeerDescription getBootstrapPeerDescription() throws IOException;
/**
* Fetch peer statuses from a remote NiFi cluster.
* Implementation of this method should fetch peer statuses from the node
* represented by the passed PeerDescription using its transport protocol.
*
* @param peerDescription a bootstrap node or one of query-able nodes lastly fetched successfully
* @return Remote peer statuses
* @throws IOException thrown when it fails to fetch peer statuses of the remote cluster from the specified peer
*/
Set fetchRemotePeerStatuses(final PeerDescription peerDescription) throws IOException;
/**
* Returns the remote instance URIs.
* @return the instance URIs
*/
String getRemoteInstanceUris();
/**
* Returns the transport protocol being used.
* @return the transport protocol
*/
SiteToSiteTransportProtocol getTransportProtocol();
}