Should KafkaProducerMessage & KafkaConsumerMessage extend AbstractMessage?

[antonkomarev]

What is the reason of extending both of KafkaProducerMessage and KafkaConsumerMessage from the AbstractKafkaMessage?

I might be wrong, but it looks like we cannot make $key and $body parameters of the KafkaConsumerMessage::__construct method strictly typed because we don't know what type of value could be passed to KafkaProducerMessage, but in KafkaConsumerMessage we are always getting a strings.

[nick-zh]

Heya, can you elaborate a bit more, sry i am not sure that i am following. key and body can be null
What part are you referring to, concerning in KafkaConsumerMessage we are always getting strings?

[antonkomarev]

I mean right now they are defined as mixed in docblocks and does not have types in method signature:

public function __construct(
    string $topicName,
    int $partition,
    int $offset,
    int $timestamp,
    $key,
    $body,
    ?array $headers
) {

I thought both of them should be ?string, am I wrong?

[nick-zh]

body for sure is mixed, it can be anything (array , string, null, etc.)
key in PHP can only be ?string but in other languages other primitive types can also be used
It would fair to change the key to ?string but mixed keeps it open, if the extension would ever support the other types as well

[antonkomarev]

Aren't they all persisted as nullable string in Kafka?

[nick-zh]

Only in the PHP implementation (at least from what i know), in Java you are able to send an int and other types as well.

[nick-zh]

Even if it is handled as string internally, you can have an avro encoded key, which can have any structure (int, string, array, etc.) at least from what i know. I haven't used anything else than string (avro and non-avro) so far 😄
If you have other insights, i am happy to discuss changes we can do ✌️

[nick-zh]

Again thx for the input, i quickly tested this out and yeah i can send an array (avro) as key, so we should open even more and make withKey for the producer accept mixed instead of ?string (issue created #65)