sgammon/GUST

/*
 * Copyright © 2020, The Gust Framework Authors. All rights reserved.
 *
 * The Gust/Elide framework and tools, and all associated source or object computer code, except where otherwise noted,
 * are licensed under the Zero Prosperity license, which is enclosed in this repository, in the file LICENSE.txt. Use of
 * this code in object or source form requires and implies consent and agreement to that license in principle and
 * practice. Source or object code not listing this header, or unless specified otherwise, remain the property of
 * Elide LLC and its suppliers, if any. The intellectual and technical concepts contained herein are proprietary to
 * Elide LLC and its suppliers and may be covered by U.S. and Foreign Patents, or patents in process, and are protected
 * by trade secret and copyright law. Dissemination of this information, or reproduction of this material, in any form,
 * is strictly forbidden except in adherence with assigned license requirements.
 */
package gust.backend.transport;

import io.micronaut.aop.Introduction;
import io.micronaut.context.annotation.Bean;
import io.micronaut.context.annotation.Type;

import javax.annotation.Nonnull;
import java.lang.annotation.*;


/**
 * Specifies an injection qualifier for a managed transport supporting the service specified by this annotation.
 *
 * <p>To use this annotation, decorate a {@link io.grpc.ManagedChannel} parameter with <code>@GoogleAPIChannel</code>,
 * and pass in the enumerated service you wish to receive a connection for. The connection will be initialized and kept
 * in a pool according to current settings and load.</p>
 *
 * <p>For more information about how connections are managed and integrated with Micronaut,
 * see {@link GoogleTransportManager}.</p>
 *
 * @see GoogleTransportManager
 **/
@Bean
@Documented
@Introduction
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Type(GoogleTransportManager.class)
public @interface GoogleAPIChannel {
  /**
   * Service for which this annotation is requesting a {@link io.grpc.ManagedChannel} instance.
   *
   * <p>If no connection to the requested service exists, one will be initialized before being handed back to the user.
   * Otherwise, the user may get an existing singleton connection instance, or a connection instance from a pool of
   * connections, depending on the implementing {@link TransportManager} (usually {@link GoogleTransportManager}).</p>
   *
   * @return Service to return a managed connection for.
   */
  @Nonnull GoogleService service();
}