RFC: Change createdAt format on MessageConverter

[prolic]

Current MessageConverter actually doesn't convert the createdAt field but returns a DateTimeImmutable object, which means that in order to send via network you have to convert it again to string.

I would like to propose that the createdAt field will get converted to string by default with format 'Y-m-d\TH:i:s.u\Z

Thoughts?

/cc @fritz-gerneth @enumag @basz

[basz]

sound logical to have everything ready to be sent via a network.The uuid is also converted.

'uuid' => $message->uuid()->toString(),

That's not an ATOM format you propose cause it contains microseconds. Isn't there a DateTime::ATOM_WITH_MICRO format out there?

[prolic]

The uuid is already converted to string, and no, there is no ATOM_WITH_MICRO format or anything else that comes near.

[enumag]

Afaik there is only DateTime::RFC3339_EXTENDED which only contains milliseconds, not microseconds. None of the formats in DateTime constants has microseconds sadly.

👍 on this proposal although I'd use P for timezone instead of Z.

[fritz-gerneth]

Yes please. This certainly is part of message serialization.

Not sure about the timezone part though. We just run everything on UTC and convert it to local time where necessary. I understand MySQL does this on the DB level only for TIMESTAMP but not for DATETIME, making it just drop the timezone information. This potentially would cause serious issues should events be created in different timezones anyway? For other DBs I have no knowledge how they behave.

[prolic]

We recommend already to use UTC, however you're free to use something else (even if that's stupid).

[prolic]

Implemented on develop-branch: https://github.com/prooph/common/tree/develop

[prolic]

This library will receive support until December 31, 2019 and will then be deprecated.

For further information see the official announcement here: https://www.sasaprolic.com/2018/08/the-future-of-prooph-components.html