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A library used at otto.de to implement Spring Boot based event-sourcing microservices.

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package de.otto.synapse.annotation;

import de.otto.synapse.channel.selector.MessageLog;
import de.otto.synapse.configuration.MessageLogReceiverEndpointAutoConfiguration;
import de.otto.synapse.endpoint.receiver.MessageLogReceiverEndpoint;
import de.otto.synapse.endpoint.receiver.MessageLogReceiverEndpointFactory;
import org.springframework.context.annotation.Import;

import java.lang.annotation.*;


@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import({MessageLogReceiverEndpointBeanRegistrar.class, MessageLogReceiverEndpointAutoConfiguration.class})
@Repeatable(EnableMessageLogReceiverEndpoints.class)
public @interface EnableMessageLogReceiverEndpoint {

    /**
     * The name of the message-log channel.
     * 
     * Resolving placeholders like "${my.channel.name}" is supported for this property.
     * 
     *
     * @return channel name
     */
    String channelName();

    /**
     * The name of the registered MessageLogReceiverEndpoint bean.
     * 
     * If {@code #name} is not set, the name of the bean is derived from the name of the message channel. The name
     * is constructed by tranforming hyphenated variable naming convention, e.g., "my-channel" into
     * the Spring bean naming convention, e.g., "myChannel". After this conversion, the string
     * "MessageLogReceiverEndpoint" is appended. A channel named "my-channel" will therefore result in a bean name
     * "myChannelMessageLogReceiverEndpoint".
     * 
     *
     * @return bean name
     */
    String name() default "";

    /**
     * Specifies where to start reading from the message log.
     * Possible Values:
     * 
     *     HORIZON (default): Start reading from the oldest available message
     *     LATEST: Start reading from the latest message
     * 
     *
     * @return LATEST or HORIZON
     */
    String startFrom() default "HORIZON";

    /**
     * Selector used to select one of possibly multiple available
     * {@link MessageLogReceiverEndpointFactory} instances used to
     * create the {@link MessageLogReceiverEndpoint}.
     *
     * 
     * Example: the KafkaMessageLogReceiverEndpointFactory matches both {@link MessageLog MessageLog.class}
     * and Kafka.class. The following usage of the annotation is selecting the KafkaMessageLogReceiverEndpointFactory
     * using the more specific Kafka selector:
     * 
     * 
     * {@literal @}Configuration
     * {@literal @}EnableMessageLogReceiverEndpoint(
     *      channelName = "some-log",
     *      selector = Kafka.class)
     * class MyExampleConfiguration {
     * }
     * 
     *
     * @return MessageLog selector class
     */
    Class selector() default MessageLog.class;

}