Sender Result Channel

从版本 4.0.3 开始，可以配置 resultMetadataChannel 以接收 SenderResult<?>，从而确定发送的成功/失败。

Starting with version 4.0.3, you can configure the resultMetadataChannel to receive SenderResult<?> s to determine success/failure of sends.

SenderResult 包含 correlationMetadata，允许将结果与发送相关联；它还包含 RecordMetadata，指示已发送记录的 TopicPartition 和偏移量。

The SenderResult contains correlationMetadata to allow you to correlate results with sends; it also contains RecordMetadata, which indicates the TopicPartition and offset of the sent record.

resultMetadataChannel 必须是 FluxMessageChannel 实例。

The resultMetadataChannel must be a FluxMessageChannel instance.

以下是使用此功能（具有类型为 Integer 的相关元数据）的一个示例：

Here is an example of how to use this feature, with correlation metadata of type Integer:

@Bean
FluxMessageChannel sendResults() {
    return new FluxMessageChannel();
}

@ServiceActivator(inputChannel = "sendResults")
void handleResults(SenderResult<Integer> result) {
    if (result.exception() != null) {
        failureFor(result);
    }
    else {
        successFor(result);
    }
}

要在输出记录上设置相关元数据，请设置 CORRELATION_ID 标头：

To set the correlation metadata on an output record, set the CORRELATION_ID header:

streamBridge.send("words1", MessageBuilder.withPayload("foobar")
        .setCorrelationId(42)
        .build());

在使用带有 Function 的该功能时，函数的输出类型必须是一个带有已设置至期望值的关联 ID 标头的 Message<?>。

When using the feature with a Function, the function output type must be a Message<?> with the correlation id header set to the desired value.

元数据应该唯一，至少在发送过程中唯一。

Metadata should be unique, at least for the duration of the send.