Quarkus Reactive Messaging NATS JetStream

https://docs.quarkiverse.io/quarkus-reactive-messaging-nats-jetstream/dev
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A Quarkus extension that enables NATS JetStream messaging support in Quarkus applications through...
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### Interact with NATS Key/Value Store using Java

Source: https://docs.quarkiverse.io/quarkus-reactive-messaging-nats-jetstream/dev/index.html

A Java resource class demonstrating how to use the NATS Key/Value store client for getting, putting, and deleting data.

```java
@Path("/key-value")
@Produces("application/json")
@RequestScoped
class KeyValueStoreResource {
    private final Client client;

    @Inject
    public KeyValueStoreResource(Client client) {
        this.client = client;
    }

    @GET
    @Path("{key}")
    public Uni<Data> getValue(@PathParam("key") String key) {
        return client.getValue("test", key, Data.class);
    }

    @PUT
    @Path("{key}")
    @Consumes("application/json")
    public Uni<Long> putValue(@PathParam("key") String key, Data data) {
        return client.putValue("test", key, data);
    }

    @DELETE
    @Path("{key}")
    @Consumes("application/json")
    public Uni<Void> deleteValue(@PathParam("key") String key) {
        return client.deleteValue("test", key);
    }
}
```

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### Configure NATS Key/Value Store

Source: https://docs.quarkiverse.io/quarkus-reactive-messaging-nats-jetstream/dev/index.html

Configure the NATS connection and a Key/Value store named 'test' with in-memory storage.

```properties
quarkus.messaging.nats.connection.servers=nats://localhost:4242
quarkus.messaging.nats.connection.username=guest
quarkus.messaging.nats.connection.password=guest
quarkus.messaging.nats.connection.ssl-enabled=false

# Creates a "test" bucket stored in memory. This part is optional. If you already have created a bucket on NATS
# then this configuration is redundant.
quarkus.messaging.nats.key-value-stores.test.storage-type=Memory
quarkus.messaging.nats.key-value-stores.test.description=Test bucket
```

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### Add Maven Dependency

Source: https://docs.quarkiverse.io/quarkus-reactive-messaging-nats-jetstream/dev/index.html

Add the io.quarkiverse.reactivemessaging.nats-jetstream:quarkus-reactive-messaging-nats-jetstream extension to your Maven POM file.

```xml
<dependency>
    <groupId>io.quarkiverse.reactivemessaging.nats-jetstream</groupId>
    <artifactId>quarkus-messaging-nats-jetstream</artifactId>
    <version>3.35.0</version>
</dependency>
```

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### Consume Messages with Java

Source: https://docs.quarkiverse.io/quarkus-reactive-messaging-nats-jetstream/dev/index.html

Implement a Java consumer to process incoming messages of type Data on the 'data' channel.

```java
package inbound;

import org.eclipse.microprofile.reactive.messaging.Incoming;

import jakarta.enterprise.context.ApplicationScoped;

@ApplicationScoped
public class DataConsumer {

    @Incoming("data")
    public void consume(Data data) {
        // process your data.
    }

}
```

--------------------------------

### Configure NATS JetStream Connector

Source: https://docs.quarkiverse.io/quarkus-reactive-messaging-nats-jetstream/dev/index.html

Configure your application to use the quarkus-jetstream connector for incoming and outgoing message channels.

```properties
# Inbound
mp.messaging.incoming.[channel-name].connector=quarkus-jetstream

# Outbound
mp.messaging.outgoing.[channel-name].connector=quarkus-jetstream
```

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### Configure NATS Connection and Streams for Receiving Messages

Source: https://docs.quarkiverse.io/quarkus-reactive-messaging-nats-jetstream/dev/index.html

Configure the NATS connection details and stream/consumer settings to receive messages on the 'data' channel from the 'test' stream and 'data' subject.

```properties
quarkus.messaging.nats.connection.servers=nats://localhost:4242
quarkus.messaging.nats.connection.username=guest
quarkus.messaging.nats.connection.password=guest
quarkus.messaging.nats.connection.ssl-enabled=false

# Streams and consumers are created based on the stream configuration
quarkus.messaging.nats.streams.test.pull-consumers.data-consumer.consumer-configuration.filter-subjects=data

mp.messaging.incoming.data.connector=quarkus-jetstream
mp.messaging.incoming.data.stream=test
mp.messaging.incoming.data.consumer=data-consumer
```
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