Undertow is a new Servlet Container that is used by WildFly (JBoss Community Server). You can embed Undertow as you wish. Here's a a test that shows it in action.

import io.undertow.servlet.api.DeploymentInfo;
import org.jboss.resteasy.plugins.server.undertow.UndertowJaxrsServer;
import org.jboss.resteasy.test.TestPortProvider;
import org.junit.AfterClass;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.core.Application;
import java.util.HashSet;
import java.util.Set;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public class UndertowTest
{
   private static UndertowJaxrsServer server;

   @Path("/test")
   public static class Resource
   {
      @GET
      @Produces("text/plain")
      public String get()
      {
         return "hello world";
      }
   }

   @ApplicationPath("/base")
   public static class MyApp extends Application
   {
      @Override
      public Set<Class<?>> getClasses()
      {
         HashSet<Class<?>> classes = new HashSet<Class<?>>();
         classes.add(Resource.class);
         return classes;
      }
   }

   @BeforeClass
   public static void init() throws Exception
   {
      server = new UndertowJaxrsServer().start();
   }

   @AfterClass
   public static void stop() throws Exception
   {
      server.stop();
   }

   @Test
   public void testApplicationPath() throws Exception
   {
      server.deployOldStyle(MyApp.class);
      Client client = ClientBuilder.newClient();
      String val = client.target(TestPortProvider.generateURL("/base/test"))
                         .request().get(String.class);
      Assert.assertEquals("hello world", val);
      client.close();
   }

   @Test
   public void testApplicationContext() throws Exception
   {
      server.deployOldStyle(MyApp.class, "/root");
      Client client = ClientBuilder.newClient();
      String val = client.target(TestPortProvider.generateURL("/root/test"))
                         .request().get(String.class);
      Assert.assertEquals("hello world", val);
      client.close();
   }

   @Test
   public void testDeploymentInfo() throws Exception
   {
      DeploymentInfo di = server.undertowDeployment(MyApp.class);
      di.setContextPath("/di");
      di.setDeploymentName("DI");
      server.deploy(di);
      Client client = ClientBuilder.newClient();
      String val = client.target(TestPortProvider.generateURL("/di/base/test"))
                         .request().get(String.class);
      Assert.assertEquals("hello world", val);
      client.close();
   }
}

The Sun JDK comes with a simple HTTP server implementation (com.sun.net.httpserver.HttpServer) which you can run RESTEasy on top of.

 
      HttpServer httpServer = HttpServer.create(new InetSocketAddress(port), 10);
      contextBuilder = new HttpContextBuilder();
      contextBuilder.getDeployment().getActualResourceClasses().add(SimpleResource.class);
      HttpContext context = contextBuilder.bind(httpServer);
      context.getAttributes().put("some.config.info", "42");
      httpServer.start();

      contextBuilder.cleanup();
      httpServer.stop(0);
    

Create your HttpServer the way you want then use the org.jboss.resteasy.plugins.server.sun.http.HttpContextBuilder to initialize Resteasy and bind it to an HttpContext. The HttpContext attributes are available by injecting in a org.jboss.resteasy.spi.ResteasyConfiguration interface using @Context within your provider and resource classes.

Maven project you must include is:

 
  <dependency>
      <groupId>org.jboss.resteasy</groupId>
      <artifactId>resteasy-jdk-http</artifactId>
      <version>4.7.2.Final</version>
  </dependency>

RESTEasy has integration with the popular Netty project as well..

 
   public static void start(ResteasyDeployment deployment) throws Exception
   {
      netty = new NettyJaxrsServer();
      netty.setDeployment(deployment);
      netty.setPort(TestPortProvider.getPort());
      netty.setRootResourcePath("");
      netty.setSecurityDomain(null);
      netty.start();
   }
    

Maven project you must include is:

 
  <dependency>
      <groupId>org.jboss.resteasy</groupId>
      <artifactId>resteasy-netty4</artifactId>
      <version>4.7.2.Final</version>
  </dependency>

RESTEasy integrates with the reactor-netty project. This server adapter was created to pair with our reactor-netty based JAX-RS client integration. Ultimately, if using reactor-netty for both the server and server-contained clients you will be able to do things like share the same event loop for both server and client calls.

 
   public static void start(ResteasyDeployment deployment) throws Exception
   {
      ReactorNettyJaxrsServer server =  new ReactorNettyJaxrsServer();
      server.setDeployment(new ResteasyDeploymentImpl());
      server.setDeployment(deployment);
      server.setPort(TestPortProvider.getPort());
      server.setRootResourcePath("");
      server.setSecurityDomain(null);
      server.start();
   }
    

Maven project you must include is:

 
  <dependency>
      <groupId>org.jboss.resteasy</groupId>
      <artifactId>resteasy-reactor-netty</artifactId>
      <version>4.7.2.Final</version>
  </dependency>

RESTEasy has integration with the popular Vert.x project as well..

 
   public static void start(VertxResteasyDeployment deployment) throws Exception
   {
      VertxJaxrsServer server = new VertxJaxrsServer();
      server.setDeployment(deployment);
      server.setPort(TestPortProvider.getPort());
      server.setRootResourcePath("");
      server.setSecurityDomain(null);
      server.start();
   }
    

Maven project you must include is:

 
  <dependency>
      <groupId>org.jboss.resteasy</groupId>
      <artifactId>resteasy-vertx</artifactId>
      <version>4.7.2.Final</version>
  </dependency>
    

The server will bootstrap its own Vert.x instance and Http server.

EmbeddedJaxrsServer is an interface provided to enable each embedded container wrapper class to configurate, start and stop its container in a standard fashion. Each of UndertowJaxrsServer, SunHttpJaxrsServer, NettyJaxrsServer, and VertxJaxrsServer implements EmbeddedJaxrsServer.

 
      public interface EmbeddedJaxrsServer<T> {
         T deploy();
         T start();
         void stop();
         ResteasyDeployment getDeployment();
         T setDeployment(ResteasyDeployment deployment);
         T setPort(int port);
         T setHostname(String hostname);
         T setRootResourcePath(String rootResourcePath);
         T setSecurityDomain(SecurityDomain sc);
      }