# ReactPHP — Event-Driven Non-Blocking I/O for PHP

> ReactPHP is a low-level library for event-driven programming in PHP that provides an event loop, stream abstractions, and async I/O primitives for building non-blocking network applications.

## Install

Save in your project root:

# ReactPHP — Event-Driven Non-Blocking I/O for PHP

## Quick Use
```bash
composer require react/http
php server.php
```

## Introduction
ReactPHP brings the event-driven programming model to PHP. Inspired by Node.js and Reactor pattern implementations, it provides a composable set of libraries for building async HTTP servers, clients, and stream processors in pure PHP.

## What ReactPHP Does
- Provides an event loop for non-blocking I/O operations
- Includes an HTTP server and client for async web applications
- Offers stream abstractions for reading and writing data without blocking
- Supports async DNS resolution, filesystem access, and child processes
- Enables promise-based workflows for managing asynchronous results

## Architecture Overview
ReactPHP is organized as a collection of small Composer packages centered around the event loop component. The loop uses the best available backend (ext-ev, ext-event, ext-uv, or a stream_select fallback). All I/O components — sockets, streams, HTTP, DNS — register callbacks with the loop and process data as it becomes available, enabling a single PHP process to handle many concurrent connections.

## Self-Hosting & Configuration
- Install individual components via Composer (e.g., `react/http`, `react/socket`)
- Start the event loop with `ReactEventLoopLoop::run()`
- Configure server listening address and port in your PHP script
- Tune OS limits (file descriptors, TCP backlog) for high concurrency
- Run as a persistent process using systemd or supervisord

## Key Features
- Modular component design — use only what you need
- Promise-based async API following Promises/A+ semantics
- Built-in HTTP server capable of handling concurrent requests
- Stream processing with back-pressure support
- No C extensions required for basic functionality

## Comparison with Similar Tools
- **Swoole** — coroutine-based C extension; ReactPHP is pure PHP with callback/promise patterns
- **Workerman** — multi-process PHP server; ReactPHP is a library toolkit rather than a server framework
- **Amphp** — similar async PHP library using fibers; ReactPHP uses promises and callbacks
- **Node.js** — JavaScript event-driven runtime; ReactPHP applies the same model to PHP
- **Guzzle** — synchronous HTTP client; ReactPHP's HTTP client is fully non-blocking

## FAQ
**Q: Can ReactPHP work with existing synchronous PHP code?**
A: Blocking calls will block the entire event loop. Use ReactPHP's async alternatives or run blocking code in child processes.

**Q: Is ReactPHP production-ready?**
A: Yes. Its core components are stable and used in production for WebSocket servers, API gateways, and real-time applications.

**Q: How does ReactPHP compare to PHP Fibers?**
A: PHP Fibers (8.1+) enable coroutine-style code. ReactPHP can use fibers internally while maintaining its promise-based public API.

**Q: Does ReactPHP support WebSocket?**
A: Yes. The `react/socket` and community packages like Ratchet provide WebSocket server capabilities.

## Sources
- https://github.com/reactphp/reactphp
- https://reactphp.org

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Source: https://tokrepo.com/en/workflows/asset-19716db7
Author: AI Open Source