java - Embedding Jetty as a Servlet Container

Question

I'm using Tomcat to serve my Java Servlets and it's kinda more for me. I just need to serve, Servlet Requests alone, no static content, neither JSP, etc. So I was looking for a Servlet container that can be embedded in my Application. I felt it if stripped Jetty and use it as a Servlet Container alone, it can be more scalable and occupying small memory footprint, [I don't need Jetty's 'Web Server' and other Parts]. So I've a few questions though,

1. How do I embed Jetty in my Application Code to serve Servlet Requests alone?
2. If I embed Jetty code in my Application Code, will I be able to easily upgrade Jetty Versions?
3. I got the Jetty code here, if I have to embed Jetty's Servlet Container in my App, which one should I use from the source, http://git.eclipse.org/c/jetty/org.eclipse.jetty.project.git/snapshot/jetty-9.0.3.v20130506.tar.bz2 , jetty-9.0.3.v20130506/jetty-servlet or jetty-9.0.3.v20130506/jetty-servlets

I intend to serve API Requests with my Applications and I'm looking for Performance and Scalability as main constraints. And of course Servlet 3.0 support.

Answer 1

What you are looking for is running Jetty in an embedded scenario.

There's plenty of examples available showing how to tie together the various pieces you need to accomplish your goals.

Check out the embedded examples in the jetty source tree.

For the record, jetty standalone is really just jetty embedded with a few startup and classpath related bootstraps. It is the same code, and assembled in basically the same way.

Since you stated you want Servlet 3.0, have no interest in JSP, this is rather easy to setup. (JSP is trickier to setup, but possible).

For servlet 3.0 specific embedding, there's a complete example project hosted at github.

https://github.com/jetty-project/embedded-servlet-3.0

In short, you'll have the following initialization code.

package com.company.foo;

import org.eclipse.jetty.annotations.AnnotationConfiguration;
import org.eclipse.jetty.plus.webapp.EnvConfiguration;
import org.eclipse.jetty.plus.webapp.PlusConfiguration;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.webapp.Configuration;
import org.eclipse.jetty.webapp.FragmentConfiguration;
import org.eclipse.jetty.webapp.MetaInfConfiguration;
import org.eclipse.jetty.webapp.TagLibConfiguration;
import org.eclipse.jetty.webapp.WebAppContext;
import org.eclipse.jetty.webapp.WebInfConfiguration;
import org.eclipse.jetty.webapp.WebXmlConfiguration;

public class EmbedMe {
    public static void main(String[] args) throws Exception {
        int port = 8080;
        Server server = new Server(port);

        String wardir = "target/sample-webapp-1-SNAPSHOT";

        WebAppContext context = new WebAppContext();
        // This can be your own project's jar file, but the contents should
        // conform to the WAR layout.
        context.setResourceBase(wardir);
        // A WEB-INF/web.xml is required for Servlet 3.0
        context.setDescriptor(wardir + "WEB-INF/web.xml");
        // Initialize the various configurations required to auto-wire up
        // the Servlet 3.0 annotations, descriptors, and fragments
        context.setConfigurations(new Configuration[] {
                            new AnnotationConfiguration(), 
                            new WebXmlConfiguration(),
                            new WebInfConfiguration(), 
                            new TagLibConfiguration(),
                            new PlusConfiguration(), 
                            new MetaInfConfiguration(),
                            new FragmentConfiguration(), 
                            new EnvConfiguration() });

        // Specify the context path that you want this webapp to show up as
        context.setContextPath("/");
        // Tell the classloader to use the "server" classpath over the
        // webapp classpath. (this is so that jars and libs in your
        // server classpath are used, requiring no WEB-INF/lib 
        // directory to exist)
        context.setParentLoaderPriority(true);
        // Add this webapp to the server
        server.setHandler(context);
        // Start the server thread
        server.start();
        // Wait for the server thread to stop (optional)
        server.join();
    }
}