Method NextAsync

Namespace

NATS.Client.JetStream

Assembly

NATS.Client.JetStream.dll

NextAsync<T>(INatsDeserialize<T>?, NatsJSNextOpts?, CancellationToken)

Consume a single message from the stream using this consumer.

public ValueTask<NatsJSMsg<T>?> NextAsync<T>(INatsDeserialize<T>? serializer = null, NatsJSNextOpts? opts = null, CancellationToken cancellationToken = default)

Parameters

serializer INatsDeserialize<T>

Serializer to use for the message type.

opts NatsJSNextOpts

Next message options. (default: 30 seconds timeout)

cancellationToken CancellationToken

A CancellationToken used to cancel the call.

Returns

ValueTask<NatsJSMsg<T>?>

Message retrieved from the stream or NULL

Type Parameters

T

Message type to deserialize.

Examples

The following example shows how you might process messages:

var next = await consumer.NextAsync<Data>();
if (next is { } msg)
{
    // process the message
    await msg.AckAsync();
}

Remarks

If the request to server expires (in 30 seconds by default) this call returns NULL.

This method is implemented as a fetch with MaxMsgs=1 which means every request will create a new subscription on the NATS server. This would be inefficient if you're consuming a lot of messages and you should consider using fetch or consume methods.

Exceptions

NatsJSProtocolException

Consumer is deleted, it's push based or request sent to server is invalid.

NatsJSException

There is an error sending the message or this consumer object isn't valid anymore because it was deleted earlier.