# Jetty — Lightweight Embeddable Java Web Server

> Eclipse Jetty is a high-performance HTTP server and servlet container that can be embedded into Java applications or run standalone, supporting HTTP/2, HTTP/3, and WebSocket.

## Install

Save in your project root:

# Jetty — Lightweight Embeddable Java Web Server

## Quick Use
```java
// Embedded Jetty server in 5 lines
Server server = new Server(8080);
server.setHandler(new AbstractHandler() {
    public void handle(String target, Request baseRequest,
        HttpServletRequest req, HttpServletResponse resp) {
        resp.setStatus(200);
        resp.getWriter().println("Hello from Jetty");
        baseRequest.setHandled(true);
    }
});
server.start();
```

## Introduction
Eclipse Jetty is a Java-based web server and servlet container used in production by thousands of organizations. Its embeddable design means you can start a full HTTP server from a `main()` method with a few lines of code, avoiding the overhead of deploying WAR files to an external container. Jetty also runs as a standalone distribution for traditional deployments.

## What Jetty Does
- Serves HTTP/1.1, HTTP/2, and HTTP/3 (QUIC) traffic with a unified handler API
- Implements the Jakarta Servlet, WebSocket, and JSP specifications
- Embeds directly into Java applications as a library dependency
- Provides an asynchronous I/O layer built on Java NIO for high concurrency
- Supports TLS, ALPN, and proxy protocols out of the box

## Architecture Overview
Jetty is built around a Connector-Handler pipeline. Connectors accept network connections and negotiate protocols; Handlers process requests. Handlers can be composed into trees — a ContextHandlerCollection routes by path, a ServletHandler dispatches to servlets, and a GzipHandler compresses responses. The underlying transport layer uses an event-driven I/O model with configurable thread pools. This architecture allows Jetty to handle tens of thousands of concurrent connections on modest hardware.

## Self-Hosting & Configuration
- Embed via Maven/Gradle: add `jetty-server` and `jetty-servlet` dependencies
- Create a `Server` instance, attach handlers or servlets, and call `server.start()`
- For standalone use, download the Jetty distribution and deploy WAR files into `$JETTY_BASE/webapps`
- Configure connectors, thread pools, and TLS in `jetty.xml` or programmatically
- Enable HTTP/2 by adding the `jetty-http2` module and configuring ALPN

## Key Features
- Embeddable design — no external container needed, perfect for microservices
- Full HTTP/2 and experimental HTTP/3 support with automatic protocol negotiation
- Low memory footprint compared to full application servers
- Proven at scale — used by Google App Engine, Eclipse IDE, and Jenkins
- Active maintenance under the Eclipse Foundation with frequent releases

## Comparison with Similar Tools
- **Tomcat** — Similar servlet container; Jetty is lighter and more embed-friendly while Tomcat is more widely used standalone
- **Undertow** — Red Hat's embeddable server; Jetty has broader protocol support including HTTP/3
- **Netty** — Low-level network framework; Jetty provides servlet-level abstractions on top
- **Spring Boot embedded** — Uses Tomcat, Jetty, or Undertow under the hood; Jetty is one of the pluggable options
- **Nginx/Caddy** — Native reverse proxies; Jetty is a Java application server, not a general-purpose proxy

## FAQ
**Q: Can I use Jetty as a reverse proxy?**
A: Yes. Jetty includes a ProxyServlet and an AsyncProxyServlet for forwarding requests to upstream services.

**Q: How does Jetty compare to Tomcat for Spring Boot?**
A: Both work as embedded containers in Spring Boot. Jetty tends to use less memory and starts faster; Tomcat has broader community adoption.

**Q: Does Jetty support Jakarta EE?**
A: Jetty 12 supports both javax and jakarta namespaces through its environment abstraction, making migration seamless.

**Q: What Java version does Jetty require?**
A: Jetty 12 requires Java 17 or later. Jetty 11 supports Java 11+.

## Sources
- https://github.com/jetty/jetty.project
- https://jetty.org/docs/

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Author: AI Open Source