This PR was squashed before being merged into the 4.1-dev branch (closes#26945).
Discussion
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[Messenger] Support configuring messages when dispatching
| Q | A
| ------------- | ---
| Branch? | master <!-- see below -->
| Bug fix? | no
| New feature? | yes <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks? | no <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass? | see CI checks <!-- please add some, will be required by reviewers -->
| Fixed tickets | N/A <!-- #-prefixed issue number(s), if any -->
| License | MIT
| Doc PR | todo
For now, this is mainly a RFC to get your opinion on such a feature (so it misses proper tests).
Supporting wrapped messages out-of-the-box would mainly allow to easily create middlewares that should act only or be configured differently for specific messages (by using wrappers instead of making messages implements specific interfaces and without requiring dedicated buses). For instance, I might want to track specific messages and expose metrics about it.
The Symfony Serializer transport (relates to #26900) and Validator middleware serve as guinea pigs for sample purpose here. But despite message validation usually is simple as it matches one use-case and won't require specific validation groups in most cases, I still think it can be useful sometimes. Also there is the case of the [`AllValidator` which currently requires using a `GroupSequence`](https://github.com/symfony/symfony/pull/26477) as a workaround, but that could also be specified directly in message metadata instead.
## Latest updates
PR updated to use a flat version of configurations instead of wrappers, using an `Envelope` wrapper and a list of envelope items.
Usage:
```php
$message = Envelope::wrap(new DummyMessage('Hello'))
->with(new SerializerConfiguration(array(ObjectNormalizer::GROUPS => array('foo'))))
->with(new ValidationConfiguration(array('foo', 'bar')))
;
```
~~By default, Messenger protagonists receive the original message. But each of them can opt-in to receive the envelope instead, by implementing `EnvelopeReaderInterface`.
Then, they can read configurations from it and forward the original message or the envelope to another party.~~
Senders, encoders/decoders & receivers always get an `Envelope`.
Middlewares & handlers always get a message. But middlewares can opt-in to receive the envelope instead, by implementing `EnvelopeReaderInterface`.
Commits
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749054a1e8 [Messenger] Support configuring messages when dispatching
