Develop Reference

How does a Swing client communicate with a Java EE backend?

I want to develop a Swing client application that will use a Java EE 6 backend. How does the Swing client communicate with the server? Do I have to make a web service that the communication go through or are there other ways?

There are other ways also in addition to web services.
One very common approach is RMI or Remote Method Invocation. It is a native extension of the Java platform that allows server-side objects to be directly accessible inside client-side code.
If you have no experience with RMI then take a look at the official Java Remote Method Invocation Tutorial

I think this might be a very useful document for you, complete with diagrams to demonstrate the architecture and communication modal.

There are to many communication types:
sockets gives to you the max communication speed.
a little communication overhead, you can use XML / SOAP
(plain)webservices too : fastest to implement. a HTTP GET, POST
RMI: I think is deprecated, but others are using. If you want only with Java backend from Java, you can use it

Yes, you can either create a web service (SOAP or RESTful), but since your client is a java application you can use jndi lookup to call EJB3 beans, it will work through rmi or soap, depending or your configuration. Something like here.

Developing a RMI application

I am trying to develop a simple database application, I wish to use RMI technology for this. What I need to know is, are there any common frameworks for developing RMI applications or do we have to develop the server and clients from beginning?

Maybe you should take a look at the: Remoting and web services using Spring. And there you have simple example of this approach.

Looking for simple way of communication between JavaScript and Java

Intro: I want to develop simple multiplayer Five in row (Gomoku). Front-end should be done using JavaScript, and back-end in Java.
Basically client and server should exchange pairs of integer numbers and game id. It's easy to do on client side with WebSockets, but...
Question: Is there simple way to process communication on server side, using Sockets and ServerSocket, without embedding Jetty or any other server?

Since Front-end is javascript it might run in a web browser. To communicate with the server most likely using http, then embedding Jetty and using dwr is the simplest way IMO.

If you intend to do such thing on a web project, have a look at the DWR project.

WebSockets browser support is poor at the moment.
If you're creating a Web application the mainstream solution for JS-Java communication is Ajax with some JS framework like jQuery or Dojo. It will not require any libs on the server side (unlike DWR) and also you don't need to put any JS stuff on your server if you use CDN.

Integration JS and Java

I have two systems to integrate: 1)desktop application (Java6) and 2)web-application (HTML,JS). I want first application to share some services to the second one. How could simply I do that ? I want some simple solution.
Thanks!

Expose them as standards Web Services or RESTful web-services

For an application to serve services, it should start server socket on port and listening on it. Or it should be using webservices. JDK6 comes with WebServices support. May be you can look at it.

Need a java webservice tutorial and how to make a web service secure

I have a web service that is using:
Java (familiar)
SOAP (new to me)
JBOSS (new to me)
The web service is currently unsecure. My task is to make it secure using https (ssl or tsl).
I am new to web services and web things in general. In the last week have gone through a tone of literature. Much of it which I think was not relevant to my project. I think that I need two things:
A pretty basic tutorial on web services (java specific)
A tutorial on making web services secured
Here are some of the tutorials I have gone through already:
SO Answer - In-process SOAP service server for Java
How to make a web service server.
Does not have instructions for the client.
Also does not specify what should happen so I am not certain that I got the propper result when navigating to the URL.
An Introductory Tutorial on Web Services, Java and XML
Pretty good description of lots of xml things and how messages are passed. Not certain but this seems more low level than what I need
Three Minutes to a Web Service
Good tutorial but in the second step one of the commands did not work.
I think that this may be because the tutorial is really old and maybe my jdk is differnt or something like that..

You can check out these frameworks
Apache axis
Apache cxf

The web service is currently unsecure. My task is to make it secure using https (ssl or tsl).
If it's just about (one-way) SSL, then this question doesn't have much to do with web services actually. It's more a web server or app server configuration issue. For JBoss, see SSLSetup or, if you are using Apache for the SSL encryption, see Apache SSL/TLS Encryption.

I would guess that you need to look at JBoss's documentation for how they handle security. Maybe this would help:
Chapter 8. Security on JBoss