I'm trying to build a Java web app that will let me browse a remote file system behind my NAT router. The client can talk outbound HTTP only.
I've got my Java client on the remote machine talking to my Tomcat server, which is then serving the data back up as web pages. Something like this:
File Server (java client) -> Web Server <- Browser
What I can't figure out is how to have the Tomcat server talk back to the remote Java client.
What I want to happen is:
User clicks on a folder in their browser.
Browser ajaxes to the server.
The Tomcat server contacts the remote java client.
The remote java client responds with the directory listing.
The Tomcat server sends back the new data formatted as HTML to the user.
I've looked at Comet and Tomcat 7's asynchronous stuff but I'm struggling!
If you need full-duplex communication over HTTP, than I strongly recommend using Atmosphere and Web Sockets. It simplifies server push a lot, and it's container agnostic (the framework).
You can use Async Http Client library for your remote java client in that case.
If you want to implement a PUSH behavior, then Commet is the way to go.
If there are few clients, perhaps you could solve your requirements by allowing the client to continuosly PULL changes from the server each few seconds.
Related
What are the possible ways in which Java Swing Application which is running on client side can communicate with server?
I've read that JSP can be used in web pages to communicate between server and client.But, is it possible to use JSP with Swing application? if so, how? It would be helpful, if it is demonstrated with simple login form. Thanks.
Any client-side application, whether it be a java swing app or otherwise, can certainly communicate with any server (assuming no network limiting architecture -- firewalls and whatnot). Your options are numerous
Raw sockets
Any one of the myriad of network protocols.
HTTP/HTTPS
FTP
SCP
et. al.
It depends on what protocol, services and applications are available on the server to connect with.
HTTP/HTTPS is very common. You'll need to manually create HTTP requests and send them to the server (assuming the server is a web server).
I have created a Socket Server application that will accept Client connections from other computers on the local network. This is application is run from a public static void main method. and is a very standard java application.
I have also created a web service that runs on tomcat, it also uses java. The web service will http post accept request from any internet connected device.
Once the web service receives a request I would like it to send instructions through the socket server and send some data to the client connected.
I would like to run the socket server applicaiton within the web service so that the web service has access to the socket server without having to connect as a client.
What is the best way to run a standard java app so that the tomcat server will start the application when it starts up? should i run it as a servlet or is there a better way to have the web service access the socket
An application opening its own server socket within a proper application server is pointless and possibly counter productive IMO.
Think about it: Tomcat is probably running on port 8080. Your application is hypothetically going to be running on port 9080. What port do you think clients will need to connect to, to consume your service? And if you answered that correctly, what service/benefit are you then expecting Tomcat to provide you, if your clients are in fact, not going to interact with tomcat at all?
You don't need a (full) application server to run your own personal server. You have the option of:
a Java web service without a web application server, which lets you deploy a full JAX-WS webservice within the vanilla JSE, no application server required
Using the jdk's embedded HTTP server to process your requests
Deploying your standalone application as a windows (or other OS) service
I want to create a web application, which is divided into two part one is client and another is server.
Client:
Client part is on the shared server.
Client is the GWT Application which only use to display data (containing only ui elements and ui events).
Client application is used by server to view and present it's own data.
Server:
The server is the simple java web service (restlet).
The server is reside behind the firewall.
The server contains actual data.
There are N number of servers.
Server does not contains any view if server wants ro view data it will use the gwt client application.
Every server uses same gwt application to view it's own data.
Note :
Client does not contains any address of the server. server will send the request to view it's data.
There is no firewall inbound exception on server firewall to access server data from out side client
I need to communicate client and server through firewall, Is there any architecture or design pattern to implement this type of application?
I don't think that the firewall can bring new restrictions to a GWT application compared with other types of applications (clients).
In case you have the GWT client on one server which makes calls to a different server you might have some issues due to same origin restriction.
This can be resolved in several ways:
- your GWT application has a server-side part which calls the other servers. And your GWT client makes normal RPC / JSON calls to the GWT server side (on the same server).
- in case you want to make directly the call on the different server from your GWT client you can use JSONP or the restygwt library.
I have created one sample chat application. In that chat application, I used JApplet and front end.
Till now I was testing my application in my desktop. It is working fine. Now I want to deploy my application over any webserver.
Now I have a few questions. Currently I am using Server socket as 8989 in my chatserver. When I was testing the application in my desktop, I used to start the server as stand alone.
What are the steps I have to follow when I deploy the application over tomcat or any other web server? Which port the client will listen?
How do I start my chat server? I am new to the socket concepts.
when you say you are hosting on the webserver, i believe that its an servlet/jsp based application , which will listen to your requests , in that case the listener will be invoked at the webserver default port either 80 / 8080 (being default). In case you want to change or check , you can go to the TOMCAT_INSTALLATION_DIR/conf/server.xml and check for tag containing the port number for weblistener, and change it to whatever value you feel like.
if thats not the case and you have your own thread which opens a socket for you , you really dont need a webserver, all you need is a host machine which will start the socket listener ( your custom) and then it will listen at the port that you have configured it to be at.
As far as I got it, you're having standalone application as a server, where you handle connections to particular port.
I think there is some confusion that should be clarified.
The very basic question is:
Why do you need your chat server to be running on the web server?
This should be clear to you prio to any later steps.
As web server is there basically to handle HTTP/S requests and that's not your case, as far as I got it. As you're probably running socket TCP/UDP communication.
For the web server however your client applet implemnentation could benefit of. If it would be referrend on a simple html page (deployed inside war) it could be simply redistributable to clients via url call in a web browser.
Maybe I'd preffer to use HTTP + JSON commununication, where you could benefit from web server usage (also on the server side) and would not need any other ports than standard ones.
Not sure if it still makes sence to answer your questions as it might be irrelevant for you, but let's see.
Answers to your questions:
Basically you need war archive (rather than jar one), as that's the one accepted by web servers. once you create it (you need to follow the correct folder/file structure inside) your app could be deployed to web server.
Which port the client will listen? Basically server is the listener here => no client port listening here.
This depends on your communication implementation decision. If still sticking with TCP/UDP one, I don't think web server would be beneficial here.
I am going to write a smart client application. This application will be swing based desktop client that will communicate with web service. I want to be a message has been sent to client from web service when any change occurs at server side file system. I wanted to use web services but I am not sure how I would implement a two-way communication between the server and client. Is it possible? If so how? If not what are the alternatives?
You have to program your client to be able to ping a request after a predefined frequency to check if there is a changes occurred on the server side. The client expect the changes occurred on the server or null if no change.