Making an Async Query

Only available in RabbitMQ

API specification

AsyncQuery model

To send an async query we need to know the AsyncQuery structure, which is represented with the next class:

public class AsyncQuery<T> {
    private final String resource;
    private final T queryData;
}

Where resource is the query name and queryData is a JSON Serializable payload.

DirectAsyncGateway interface

This abstraction uses the same interface that Commands, but specific methods

public interface DirectAsyncGateway {

    <T, R> Mono<R> requestReply(AsyncQuery<T> query, String targetName, Class<R> type);

    <T, R> Mono<R> requestReply(AsyncQuery<T> query, String targetName, Class<R> type, String domain); // Query to specific domain

    <R extends CloudEvent> Mono<R> requestReply(CloudEvent query, String targetName, Class<R> type); // Query with CloudEvent format

    <R extends CloudEvent> Mono<R> requestReply(CloudEvent query, String targetName, Class<R> type, String domain); // Query with CloudEvent format to specific domain

    <T> Mono<Void> reply(T response, From from); // Reply to a query
}

In this method the Class\<R> called type is the return type of the query, represented by a JSON Serializable object

You can send a CloudEvent or an AsyncQuery\<T> to a target application. You also can send a query to a specific domain (remote broker out of you application context).

Enabling autoconfiguration

To do an Async Query you should enable the respecting spring boot autoconfiguration using the @EnableDirectAsyncGateway annotation For example:

@RequiredArgsConstructor
@EnableDirectAsyncGateway
public class ReactiveDirectAsyncGateway {
    public static final String TARGET_NAME = "other-app";// refers to remote spring.application.name property
    public static final String SOME_QUERY_NAME = "some.query.name";
    private final DirectAsyncGateway gateway; // Auto injected bean created by the @EnableDirectAsyncGateway annotation

    public Mono<Object /*change for proper model*/> requestForRemoteData(Object query/*change for proper model*/)  {
        return gateway.requestReply(new AsyncQuery<>(SOME_QUERY_NAME, query), TARGET_NAME, Object.class/*change for proper model*/);
    }
}

After that you can do async queries from you application to a remote application that handles this command.

Example

You can see a real example at samples/async/async-sender-client