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/*
* Copyright 2020 The Hekate Project
*
* The Hekate Project 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 io.hekate.core.service;
import io.hekate.core.Hekate;
import io.hekate.core.HekateBootstrap;
import java.util.List;
/**
* « start hereEntry point to core API of {@link Hekate} services.
*
* Overview
*
* {@link Hekate} utilizes the Service-oriented approach in order to provide a fine grained control over resources utilization and
* functionality of each individual {@link Hekate} instance. Each instance can be configured with only those services that are required for
* application needs without an overhead of managing services that are never used by the application.
*
*
*
* Note: Typically applications are not required to implement their own custom services and can act purely as clients of services
* that are provided by {@link Hekate} out of the box. Custom services should be implemented only in order to extend functionality of
* existing services or provide some new functionality that is not covered by {@link Hekate} API.
*
*
* Service Interface
*
* All services must implement {@link Service} marker interface in order to be accessible via {@link Hekate#get(Class)} method and can also
* optionally implement a set of callback interfaces in order to participate in {@link Hekate} instance lifecycle.
*
*
* The following lifecycle interfaces are available (in invocation order):
*
*
* - {@link DependentService} - for resolving dependencies on other services.
* - {@link ConfigurableService} - for preparing and validating service configuration
* - {@link InitializingService} - for service state initialization before the {@link Hekate} node starts joining the cluster
* - {@link TerminatingService} - for service state cleanup when the {@link Hekate} node leaves the cluster
*
*
*
* Please see the documentation of those interfaces for more details.
*
*
* Service Factory
*
* Each service must have a {@link ServiceFactory} that is responsible for configuring and creating new service instances. Service
* factories can be registered via {@link HekateBootstrap#setServices(List)} method.
*
*
*
* Note: Each service gets {@link ServiceFactory#createService() created} only once by each {@link Hekate} node during the
* initialization phase and never gets re-created even if node leaves and then rejoins the cluster.
*
*
* @see Hekate#get(Class)
*/
public interface Service {
// No-op.
}