A lightweight, single-threaded HTTP server for the JVM built on java.nio. MicroServe uses a Node.js-style event loop with non-blocking I/O, Future-based async handlers, HTTP/1.1 keep-alive, and a familiar createServer API.

Add to your build.sbt:

libraryDependencies += "io.github.edadma" %% "microserve" % "0.2.0"

import io.github.edadma.microserve.*

@main def run(): Unit =
  val loop = new EventLoop

  val server = createServer(loop) { (req, res) =>
    req.path match
      case "/"     => res.send("Hello from MicroServe!\n")
      case "/json" => res.sendJson("""{"message": "hello"}""" + "\n")
      case _       => res.status(404).send("Not Found\n")
  }

  server.listen(3000) { () =>
    println("MicroServe listening on http://localhost:3000")
  }

  loop.run()

Handlers return Future[Unit] — the response methods (send, sendJson, sendHtml, end) return Future.unit, so synchronous handlers just work. For async work, use the loop's ExecutionContext:

import scala.concurrent.Future

val loop = new EventLoop
given scala.concurrent.ExecutionContext = loop.executionContext

val server = createServer(loop) { (req, res) =>
  Future {
    val result = someComputation()
    res.send(result)
  }.flatten
}

server.close() stops accepting new connections and closes idle keep-alive connections immediately, while letting in-flight requests finish. The drain callback fires once all active requests have completed:

server.close { () =>
  println("All connections drained")
  loop.stop()
}

• Single-threaded, non-blocking I/O via java.nio selectors
• Node.js-style event loop with microtask/macrotask separation (nextTick, setImmediate, setTimeout, setInterval)
• ExecutionContext for running Future callbacks on the event loop thread
• Ref-counted lifecycle — loop exits automatically when all work is done
• HTTP/1.1 keep-alive with 30-second idle timeouts
• Graceful shutdown — in-flight requests complete, idle connections close immediately
• Hand-rolled HTTP/1.1 request parser with configurable limits
• Simple Request/Response API with helpers for text, HTML, and JSON
• No external dependencies

ISC