Vitali Zaidman
b0974135bf
Summary: Pull Request resolved: https://github.com/facebook/react-native/pull/49358 When the network is under strain, the code responsible for detecting if the inspector proxy's connection to the client has been lost may incorrectly assume the connection is dead. This false positive occurs because the system assumes that if a pong is not received within 5 seconds of a ping, the other side has disconnected. However, I was able to consistently reproduce scenarios where a delay of more than 5 seconds (even more than 20 seconds) was followed by a return to normal ping-pong communication without any issues. Since I can't think of any issues with increasing this number, I'm increasing it to 60s. Changelog: [General][Fixed] - Disconnections of DevTools when the network is under significant strain. Reviewed By: robhogan, huntie Differential Revision: D69523906 fbshipit-source-id: 50db1e7bbe690b42421bc226aa30fd6571ba2257
@react-native/dev-middleware
Dev server middleware supporting core React Native development features. This package is preconfigured in all React Native projects.
Usage
Middleware can be attached to a dev server (e.g. Metro) using the createDevMiddleware API.
import { createDevMiddleware } from '@react-native/dev-middleware';
function myDevServerImpl(args) {
...
const {middleware, websocketEndpoints} = createDevMiddleware({
projectRoot: metroConfig.projectRoot,
serverBaseUrl: `http://${args.host}:${args.port}`,
logger,
});
await Metro.runServer(metroConfig, {
host: args.host,
...,
unstable_extraMiddleware: [
middleware,
// Optionally extend with additional HTTP middleware
],
websocketEndpoints: {
...websocketEndpoints,
// Optionally extend with additional WebSocket endpoints
},
});
}
Included middleware
@react-native/dev-middleware is designed for integrators such as @expo/dev-server and @react-native/community-cli-plugin. It provides a common default implementation for core React Native dev server responsibilities.
We intend to keep this to a narrow set of functionality, based around:
- Debugging — The Chrome DevTools protocol (CDP) endpoints supported by React Native, including the Inspector Proxy, which facilitates connections with multiple devices.
- Dev actions — Endpoints implementing core Dev Menu actions, e.g. reloading the app, opening the debugger frontend.
HTTP endpoints
DevMiddlewareAPI.middleware
These are exposed as a connect middleware handler, assignable to Metro.runServer or other compatible HTTP servers.
GET /json/list, /json (CDP)
Returns the list of available WebSocket targets for all connected React Native app sessions.
GET /json/version (CDP)
Returns version metadata used by Chrome DevTools.
GET /debugger-frontend
Subpaths of this endpoint are reserved to serve the JavaScript debugger frontend.
POST /open-debugger
Open the JavaScript debugger for a given CDP target. Must be provided with one of the following query params:
device — An ID unique to a combination of device and app, stable across installs. Implemented bygetInspectorDeviceIdon each native platform.target— The target page ID as returned by/json/listfor the current dev server session.appId(deprecated, legacy only) — The application bundle identifier to match (non-unique across multiple connected devices). This param will only match legacy Hermes debugger targets.
Example
curl -X POST 'http://localhost:8081/open-debugger?target=<targetId>'
WebSocket endpoints
DevMiddlewareAPI.websocketEndpoints
/inspector/device
WebSocket handler for registering device connections.
/inspector/debug
WebSocket handler that proxies CDP messages to/from the corresponding device.
Contributing
Changes to this package can be made locally and tested against the rn-tester app, per the Contributing guide. During development, this package is automatically run from source with no build step.