When a debug channel is used between the Flight server and a browser
Flight client, we want to allow the same RSC stream to be used for
server-side rendering. To support this, the Edge and Node Flight clients
also need to accept a `debugChannel` option. Without it, debug
information would be missing (e.g. for SSR error stacks), and in some
cases this could result in `Connection closed` errors.
This PR adds support for the `debugChannel` option in the Edge and Node
clients for ESM, Parcel, Turbopack, and Webpack. Unlike the browser
clients, these clients only support a one-way channel, since the Flight
server’s return protocol is not designed for multiple clients.
The implementation follows the approach used in the browser clients, but
excludes the writable parts.
This lets us pass a writable on the server side and readable on the
client side to send debug info through a separate channel so that it
doesn't interfere with the main payload as much. The main payload refers
to chunks defined in the debug info which means it's still blocked on it
though. This ensures that the debug data has loaded by the time the
value is rendered so that the next step can forward the data.
This will be a bit fragile to race conditions until #33665 lands.
Another follow up needed is the ability to skip the debug channel on the
receiving side. Right now it'll block forever if you don't provide one
since we're blocking on the debug data.
This effectively lets us consume Web Streams in a Node build. In fact
the Node entry point is now just adding Node stream APIs.
For the client, this is simple because the configs are not actually
stream type specific. The server is a little trickier.
This is used to register Server References that exist in the current
environment but also exists in the server it might call into. Such as a
remote server.
If the value comes from the remote server in the first place then this
is called automatically to ensure that you can pass a reference back to
where it came from - even if the `serverModuleMap` option is used. This
was already the case when `serverModuleMap` wasn't passed. This is how
you can pass server references back to the server. However, when we
added `serverModuleMap` that pass was skipped because we were getting
real functions instead of proxies.
For functions that wasn't yet passed from the remote server to the
current server, we can register them eagerly just like we do for
`import('/server').registerServerReference()`. You can now also do this
with `import('/client').registerServerReference()`. We could make them
shared so you only have to do this once but it might not be possible to
pass to the remote server and the remote server might not even be the
same RSC renderer. Therefore I split them. It's up to the compiler
whether it should do that or not. It has to know that any function you
might call might be able to receive it. This is currently global to a
specific RSC renderer.
This implements `findSourceMapURL` in react-server-dom-parcel, enabling
source maps for replayed server errors on the client. It utilizes a new
endpoint in the Parcel dev server that returns the source map for a
given bundle/file. The error overlay UI has also been updated to handle
these stacks. See https://github.com/parcel-bundler/parcel/pull/10082
Also updated the fixture to the latest Parcel canary. A few APIs have
changed. We do have a higher level library wrapper now (`@parcel/rsc`
added in https://github.com/parcel-bundler/parcel/pull/10074) but I left
the fixture using the lower level APIs directly here since it is easier
to see how react-server-dom-parcel is used.
This adds a new `react-server-dom-parcel-package`, which is an RSC
integration for the Parcel bundler. It is mostly copied from the
existing webpack/turbopack integrations, with some changes to utilize
Parcel runtime APIs for loading and executing bundles/modules.
See https://github.com/parcel-bundler/parcel/pull/10043 for the Parcel
side of this, which includes the plugin needed to generate client and
server references. https://github.com/parcel-bundler/rsc-examples also
includes examples of various ways to use RSCs with Parcel.
Differences from other integrations:
* Client and server modules are all part of the same graph, and we use
Parcel's
[environments](https://parceljs.org/plugin-system/transformer/#the-environment)
to distinguish them. The server is the Parcel build entry point, and it
imports and renders server components in route handlers. When a `"use
client"` directive is seen, the environment changes and Parcel creates a
new client bundle for the page, combining all client modules together.
CSS from both client and server components are also combined
automatically.
* There is no separate manifest file that needs to be passed around by
the user. A [Runtime](https://parceljs.org/plugin-system/runtime/)
plugin injects client and server references as needed into the relevant
bundles, and registers server action ids using `react-server-dom-parcel`
automatically.
* A special `<Resources>` component is also generated by Parcel to
render the `<script>` and `<link rel="stylesheet">` elements needed for
a page, using the relevant info from the bundle graph.
Note: I've already published a 0.0.x version of this package to npm for
testing purposes but happy to add whoever needs access to it as well.
### Questions
* How to test this in the React repo. I'll have integration tests in
Parcel, but setting up all the different mocks and environments to
simulate that here seems challenging. I could try to copy how
Webpack/Turbopack do it but it's a bit different.
* Where to put TypeScript types. Right now I have some ambient types in
my [example
repo](https://github.com/parcel-bundler/rsc-examples/blob/main/types.d.ts)
but it would be nice for users not to copy and paste these. Can I
include them in the package or do they need to maintained separately in
definitelytyped? I would really prefer not to have to maintain code in
three different repos ideally.
---------
Co-authored-by: Sebastian Markbage <sebastian@calyptus.eu>
