Roadmap to reactphp/http v3

[clue]

ReactPHP v3 is going to happen! 🎉

We're committed to work on the next major version of ReactPHP. We've started working on this a while ago and believe it's time to finally make this public and give people a chance to see what we're up to and to contribute. In order to show the ongoing development towards ReactPHP v3, we're using dedicated roadmap tickets (like this one) for each component.

Our plans towards HTTP v3

• ✅ Prepare any remaining v1 releases v1.10.0
  There are still some outstanding features important for both HTTP v1 and v3. To avoid doubling the work and to create a clear cut to ease upgrading, we should finish any v1 releases before creating the 3.x branch.

• ✅ Create 3.x branch #527
  Once this is created, we can start working on the new v3.0.0 milestone. The default branch will be 3.x and the previous 1.x branch still stay in place at least until v3.0.0 is released.

• ✅ Drop deprecated APIs #528 #529
  All APIs marked as @deprecated in v1 will be removed in v3. Each occurrence should have a clear upgrade path described.

• ✅ Require PHP 7.1+ and recommend PHP 8.1+ #530
  Time to upgrade! The new v3 will make use of newer language features, so we will upgrade to PHP 7.1+ as a minimum requirement (to run absolutely anywhere) and recommend PHP 8.1+ looking forward (Fibers).

• Type-Safe APIs with PHPStan on max level
  All our public APIs should use native type declarations to avoid invalid API usage and guide IDEs and static analysis tools.

• Remove all optional loop parameters
  In order to introduce Fiber-based APIs and make our APIs easier to use, we're going to make the event loop entirely opaque and remove all optional loop parameters.

• Blocking APIs and async APIs
  We will rename the existing async APIs and then add new synchronous APIs using the previous names. This means you get the best of both worlds and can use whichever style works best for your use case. Each change will have a clear upgrade path described.

• Upgrade to require EventLoop, Promise, Stream & Socket v3
  All upcoming v3 components should require any other ReactPHP components from the same major version or above, so we can deprecate legacy versions in the future. May require upgrade to dev version prior to v3 release (reactphp/event-loop#271, reactphp/stream#173, reactphp/socket#312).

• Release reactphp/http v3.0.0
  Planned around mid-2024, approaching our 12th birthday? To ensure a smooth release, we will coordinate the process across all our components.

How you can help

We're optimistic to get the above things done in the near future, so this ticket aims to serve as a basic overview and is subject to change as we progress. For more details, see also the milestone links and any referenced tickets. If you have any additional input for ReactPHP v3, we invite you to join our discussion about the roadmap for the next major version.

Working on the next major version involves a lot of work and we're always looking for sponsors to allow us spending more time on ReactPHP. Check out ReactPHP's sponsors profile and consider supporting the ongoing development ❤️

We'll do our best to keep this ticket updated as we make progress. To keep things organized, let's try to limit the discussions in here and please use new tickets and discussions for input. Help us spread the word! We are excited to move forward together! 🚀