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

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.

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How to call to Java RMI methods from web client?

I have a Java RMI application developed with Swing GUI interface. I want to change that to React app. Is it possible to call RMI methods from JavaScript?
No. It is not possible. Javascript is not Java at all.
You may consider to rewrite server side of RMI application to either Webservice or REST API application, then you'll be able to call its methods from Javascript. It can be also just a small wrapper application around existing RMI.
Like:
Javascript call (SOAP or REST) -> Wrapper call (RMI) -> Existing RMI app.
Maybe, you can use hessian protocol (reimplement RMI with hessian, just delegate from hessian servlet to local RMI). Use hessian.js

communication between jruby app and java app that are on different servers

Anyone has expirience on having Jruby project running on Jboss (using torquebox or whatever) with an ability to communicate with another "japps" not on the same jboss where jruby app is, i.e. some java project on another jboss?
I know there is an torque-messanging but dunno if it's possible to communicate with external(out of jruby-app's jboss) app?
Best practices are welcomed.
Thanks in advance.
P.S. placing that other app on the jboss where jruby app is not acceptible solution.
I can recommend you to use Thrift and build communication via them.
Thrift have generator for both your needed languages (Java and JRuby) and provide good and fast communication.
UPDATED:
Thrift is RPC (remote procedure call) framework developed at Facebook. In detail you can read about it in Wiki.
In few word to save you time, what it is and how to use it:
You describe you data structures and service interface in .thrift file(files). And generate from this file all needed source files(with all need serialization) for one or few languages(what you need). Than you can simple create server and client in few lines
Using it inside client will be looks like you just use simple class.
With Thrift you can use what protocol and transport used.
In most cases uses Binary or Compact protocol via Blocked or Not-blocked transport. So network communication will be light and fast + with fast serialization.
SOAP(based on XML on HTTP) packages, its in few times bigger, and inappropriate for sending binary data, but not only this. Also XML-serialization is very slow. So with SOAP you receive big overhead. Also with soap you need to write (or use third-party) lib for calling server(tiny network layer), thrift already made it for you.
SMTP and basically JMS is inappropriate for realtime and question-answer communication.
I mean if you need just to put some message in queue and someone sometime give this message and process it — you can (and should) use JMS or any other MQ services(Thrift can do this to, but MQ architecture is better for this issue).
But if you need realtime query-answer calls, you should use RPC, as protocol it can be HTTP(REST, SOAP), binary(Thrift, ProtoBuf, JDBC, etc) or any other.
Thrift (and ProtoBuf) provide framework for generate client and server, so it incapsulate you from low level issues.
P.S:
I made some example in past https://github.com/imysak/using-thrift (communication via Thrift Java server + Java Client or node.js client), maybe it will be useful for someone . But you can found more simple and better examples.
Torquebox supports JMS. The gem you specified torquebox-messaging allows for publishing and processing of HornetQ messages on the local JBoss AS server/cluster that the JRuby app is running in. I don't think it currently supports connecting to remote servers.
Using this functionality in your JRuby app you could then configure your Java app on another server to communicate with HornetQ running in the JBoss AS that the JRuby app is running on.
Alternatively you could always implement your own communication protocol or use another Java library - you have access to anything Java you want to run from JRuby.
You can use Web Services or JMS for that

Best way to manage asynchronous / push communication with web clients on a Spring based Java server

I need to push events to web clients in a cross-browser manner (iPhone, iPad, Android, IE/FF/Chrome/etc.) from a Spring based Java server. I am using backbone.js on the client side.
To my best knowledge, I can either go with a Web socket only approach, or I can use something like socket.io.
What is the best practice for this issue, and which platform/frameworks should I use?
Thanks
Looks like you're interested in an AJAX Push engine. ICEPush (same group that makes ICEFaces) provides these capabilities, and works with a variety of server- and client-side frameworks. There is also APE.
You can have a look at Lightstreamer.
My company is currently using it to push real time financial data from a web server.
I suppose Grizzly or Netty may fit your needs. Don't have a real experience in that scope, unfortunately.
I'd recommend socket.io as you mentioned in your question, if you're doing browser based eventing from a remote host. Socket.io handles all the connection keep-alives and reconnections directly from javascript and has facilities for channeling messages to specific sessions (users). The real advantage comes from the two-way communication of WebSockets without all the boilerplate code of maintaining the connection.
You will need to do some digging for a java implementation thoughConsider running the server directly from V8.

What technology I should use to develop small Java webservice?

Basically I need webservice where client can request with id one boolean value from our webservice. What technology would be most suitable for this small API? Of course it is possible that there will be more functions to interface, but now we need only one function. It also needs to have authentication, so that only auhtorized clients can access service. And every client have different auth credientials.
What would be good technology for this purpose?
I am using resteasy to build my webservices and it is pretty easy to use ... just need to use annotations on my methods to deliver the webservices.
Here is a comparison of different JAX-RS frameworks. Take a look at it
First of all: authentication and authorization. Don't do it yourself, pick an app server or servlet container and configure it to do the job.
For the web service....
The simplest thing to do it just implement a servlet that responds to a POST (not a GET if request modifies internal state) and returns the result in the body. This way you don't need any frames works, no learning to do (if you already know servlets). The downside is it won't scale as you add more features, and your not using enough buzz words.
If you want a SOAP based webservice, then look at JAX-WS. Now that it's backed into java 6 it's pretty easy.
At the simplest level JAX-WS lets you put a few annotations on your class, like #WebService, and it auto generates a wsdl and exposes an instance of your class via the web service.
There is plenty of documenation out around how to do it:
http://java.sun.com/webservices/docs/2.0/tutorial/doc/
http://www.java-tips.org/java-ee-tips/java-api-for-xml-web-services/developing-web-services-using-j.html
http://cwiki.apache.org/GMOxDOC20/simple-web-service-with-jax-ws.html
JAX-WS + any servlet container (Tomcat is usual choice)
#WebService(targetNamespace = "http://affinity.foo.com", name="RewardsStatus")
#SOAPBinding(style=SOAPBinding.Style.RPC, use=SOAPBinding.Use.LITERAL)
public interface RewardsStatusIF {
#WebMethod(operationName="GetLastNotificationDate", action="urn:GetLastNotificationDate")
#WebResult(name="return")
public Date getLastNotificationDate() throws AffinityException;
...
Actually, you don't even need a servlet container. JAX-WS has a way to run the service under a standalone Java application. It has some limitations (I have failed to make a stateful service work), but it's
very simple to create.
Given that you tagged your question as "Java", I suggest Jetty. It is a very good small servlet engine. It has support for sessions, so adding authentication should not be a problem.
If you are using Java 6, there is already a HTTP Server builtin, it supports Http authentication. That's all you need. Check out,
com.sun.net.httpserver
You could use some restful framework like jersey.
An alternative to SOAP-based web services with JAX-WS would be JAX-RS (for RESTful web services).
We have a lot of scenarios on our project where we want small amounts of data available via simple HTTP URLs while the app is running and in my experience, Restlet (http://www.restlet.org/) seems to be one of the easiest things available for setting up simple "web-service"-like interfaces (RESTful interfaces) within Java apps.

java: basic web service interface without a web server

how hard is adding a basic web services interface to an existing java server application without having to turn it into a .war, or embedding a small web server like jetty?
say, xml-rpc instead of more modern approaches, if it helps.
if not too hard, can you suggest a starting point?
thank you in advance :)
It sounds like you're asking for the impossible: expose an HTTP service without plugging into or embedding an HTTP server!
Unless you want to reimplement what Jetty already does, I'd reccommend using Jetty as a library. That way you don't need to conform to the more awkward aspects of the Servlet spec. E.g. your servlets can have real constructors with parameters.
There is also a simple HTTP server implementation in JDK 6, but it's in the com.sun namespace so I'd avoid it for production code.
Check out the Restlet API which provides a painless way to implement RESTful web services that can run inside a web container or standalone.
I don't know what you are doing, but what about rmi?
RMI # stackoverflow
Spring-WS has the facility for using JRE 1.6's embedded web server, if that's an option for you. Spring-WS gives you a very nice SOAP server layer, if that's what you're after.
If not, then an embedded Jetty instance is probably the best idea.

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