sending client to client messages without server i

问题:

I am not sure if I can explain this correctly…. But is there a way to send a message from one client to another without bringing the server into interaction…. I mean the server will setup the channel between two clients and the clients will communicate using that channel only…. No server interaction what so ever… much of what like pubnub does… so basically what I am trying to do is build something like pubnub… I know it is possible… if I’m not mistaken that is….. So, what are the things I need to get started… oh and I'm not sure what tag to put this question in... basically i want something like the following picture...

回答1:

You can not do this with PHP, JavaScript or WebSockets. If you will open a connection between two clients, clients' system must allow a port to open at least. Which can not be done any of these. It requires an access to OS. If you could do this from browser, it would be a security issue.

You may can do this with a Java applet if it had to be done through browser. Which accesses to underlying JVM which can access to OS functions with proper permissions.