What web server should I use if I want to run Java code behind it?

Question

At the moment, I have lot's of Java which does all kind of nifty stuff and I'm happy with it. The code is command line driven which have been great so far, but I recently decided I want to make the functionality available through web-services. Since my is complex and I'm happy with the way it's written , I don't want go through the pain of porting it to other languages. So I set out on a google journey to find out what web servers exist (on a Linux machine, though it's interesting to hear the answer without that limitation).

From what I could find, it seems that there are two viable options: Apache Tomcat and Sun Java Server.

What are the reason to choose one on top of the other? what are the strength of each and what are the weaknesses? Or, perhaps, there is a third one which is much easier, flexible and less cumbersome.

Anyone?

Answer 1

Easy, flexible and not cumbersome, that would be Jetty, but also Simpleweb might be useful. You dont say much about your software so i'm not really sure, but for a command line program, I don't think you need all the JavaEE stuff.
The mainstream servers are these.
I think the Apache Tomcat vs Glassfish (Sun Java Server) discussion is irrelevant for your needs, any would do.

Answer 2

Apache Tomcat should do good.

Answer 3

There are many containers for Java web applications, they all have their own strengths and weaknesses. If you're looking for a container to support a business application, you should probably take a look at how they differ and work out which suits your business and IT drivers.

The key thing is that they all support the servlet specification - your webapps can run in any of them - which means you can change your mind easily. Some of them will also support more of the Java Enterprise Edition specs, so may be too heavy for your needs.

If you're just getting started, I'd suggest Tomcat. It's basic, but it's reliable, quick to run and start up, and it's got a really easy web-based webapp deployment interface.

Answer 4

Your question is actually a bit too ambiguous and wide. You can in fact run Java code at any machine you like, regardless of the language you programmed the webbased interface in. You can for example create a PHP based website which interacts with a "backend" Java application (the "command line application" as you call it). The only requirement is to have a JRE at the server machine. Then basically everything as web interface suffices: CGI, PHP, ASP, Python, etcetera, you name it. As long as it has access to the underlying commandline runtime, which is in the PHP example to be done by exec().

But Java, actually Java EE, also provides a web application programming interface: the JSP/Servlet API, the web component of the large Java EE API. This make integration with the "commandline Java application" much more seamless. You can basically just put your application in the classpath and import/access/use it in a Servlet class the real Java way:

YourApplication app = new YourApplication();
Result result = app.doStuff();
// ...

To be able to run JSP/Servlet (JSP is at end actually also a Servlet), you need a concrete implementation of the Servlet API (the whole Java EE is just an abstract specification). Apache Tomcat is good to start with, the other popular alternative being Eclipse Jetty. Those are 'simple' servletcontainers which implements the Servlet API, with Jetty being a more embedded approach of it (you can configure and run it as a "plain vanilla" Java Application). But if you need to support/cover the other aspects of the Java EE API as well, then you need an application server, such as Sun Glassfish or JBoss AS (both which by the way uses Tomcat as the servletcontainer part).

To learn more about JSP/Servlet, I can recommend the Coreservlets.com tutorials.

Answer 5

The standard concept for running code inside a web server is the "Servlet API" from Sun.

Essentially it provides a few interfaces which the web server uses to invoke your code, and defines how the web server should behave. This allows you to write very generic code that can run in a variety of web containers which implement the Servlet API. See the Wikipedia article for details - http://en.wikipedia.org/wiki/Java_Servlet.

They come in all sizes too, depending on your needs. Some small enough for embedding in your own application, some very big. The servlet API allows you not to care.

For a beginner, the quickest way to get up and running, is to download the full version of Netbeans which includes full support for doing this kind of work, and has a built in servlet container.