Servlets comunication with Applets

[Andreex]

Hi... I am making the fomous and well known : "Chat Program"

I want to do it with servlets and applets. I did some research and I founf that servlets take post from an HTML page to comunicate with the client. With an Applet you could send data thru a URL object and get it in the servlets like if it were a GET POST. So.. far.. I am doing ok. Now... how do I comunicate from the Servlet to the Applet?!?!?! Any ideas?

Thank you for any help!

[CaptainPinko]

use a HTTP socket?

java.net.*

look into sockets and serversockets or something of that name-like, though you may have problems b/c applets have alot of security mamager restrictions placed on them

[Andreex]

Yes... I alredy did the chat program with Sockets and ServerSockets.... it works really nice.... in my computer. But in public free servers they dont let you run java pro using sockets since you have to take over a port. (even thoug there is like 36665 ports... or something like that).

I was thinking to use the URL class to get information from the servlet now... If somebody can help me... how, for example, can I get the HTML CODE with and URL from lets say.... www.yahoo.com/something.html?

Thank you

[Cudabean]

Yep, there's a problem there because your http connection is normally used for a quick 2 way communication: applet->servlet and an immediate servle->applet response. Web servers often are able to send data to idling browsers, like traffic web pages that send an update every minute. I would think that you would be able to do a similar thing so that when a chat response finally comes in, the applet will receive the information from the servlet.

What about the design of this thing? You will need to think about what's going to happen. If you have three users, you will have three servlet instances running (one servlet replicated three times) How will one instance of the servlet talk to another instance? One clue is you can use static variables which will have consistent values for all instances of the servlets.

cudabean

[CaptainPinko]

you could also use sockets that connect to ports on the loop back address: 127.0.0.1 or writing to a file, but that would be slow, but convient for one-time data (like user lists or something) not the messages themselves