com.hazelcast.spi.discovery.integration.DiscoveryService Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2020, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.spi.discovery.integration;
import com.hazelcast.cluster.Member;
import com.hazelcast.spi.discovery.DiscoveryNode;
import com.hazelcast.spi.discovery.DiscoveryStrategy;
import com.hazelcast.spi.discovery.NodeFilter;
import java.util.Map;
/**
* The DiscoveryService interface defines the basic entry point
* into the Discovery SPI implementation. If not overridden explicitly the Hazelcast
* internal {@link com.hazelcast.spi.discovery.impl.DefaultDiscoveryService}
* implementation is used. A DiscoveryService somehow finds available
* {@link DiscoveryStrategy}s inside the classpath and manages their activation
* or deactivation status.
*
* This interface is used by system integrators, integrating Hazelcast into their own
* frameworks or environments, are free to extend or exchange the default implementation
* based on their needs and requirements.
*
* Only enabled providers are expected to discover nodes but, depending on the
* DiscoveryService implementation, multiple {@link DiscoveryStrategy}s
* might be enabled at the same time (e.g. TCP-IP Joiner with well known addresses
* and Cloud discovery).
*
* @since 3.6
*/
public interface DiscoveryService {
/**
* The start method is called on system startup to implement simple
* lifecycle management. This method is expected to call
* {@link DiscoveryStrategy#start()} on all discovered and start up strategies.
*/
void start();
/**
* Returns a discovered and filtered, if a {@link NodeFilter} is setup, set of
* discovered nodes to connect to.
*
* @return a set of discovered and filtered nodes
*/
Iterable discoverNodes();
/**
* The start method is called on system startup to implement simple
* lifecycle management. This method is expected to call
* {@link DiscoveryStrategy#destroy()} on all discovered and destroy strategies
* before the service itself will be destroyed.
*/
void destroy();
/**
* Returns a map with discovered metadata provided by the runtime environment. Those information
* may include, but are not limited, to location information like datacenter, rack, host or additional
* tags to be used for custom purpose.
*
* Information discovered from this method are copied into the {@link Member}s
* attributes. Existing attributes will be overridden.
*
* The default implementation provides an empty map with no further metadata configured. Returning
* null is not permitted and will most probably result in an {@link NullPointerException}
* inside the cluster system.
*
* @return a map of discovered metadata as provided by the runtime environment
* @since 3.7
*/
Map discoverLocalMetadata();
}