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How can I use RMI with a applet client behind a firewall?
How can I use RMI with a firewalled server and firewalled applet client? (If possible)
I know that the RMI server uses port 1099 (by default, but this is configurable); however after this the communication requires a new socket on a different random port. I also know that you can set the proxy on the client for RMI over HTTP tunneling which in theory should solve my issue. But I can't make it work (I tried setting the environmental properties on my XP client, but Internet Explorer keeps ignoring them).
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By default, the RMI Registry uses port 1099. By default, RMI remote objects use a random system-allocated port, unless a fixed port has been specified when exporting a remote object.
RMI stands for Remote Method Invocation. It is a mechanism that allows an object residing in one system (JVM) to access/invoke an object running on another JVM. RMI is used to build distributed applications; it provides remote communication between Java programs. It is provided in the package java.
A proxy object is an object on one "side" of an RMI connection which represents an object which really exists on the other side. When an RMI::Client calls a method on its associated RMI::Server, and that method returns a reference of any kind, a proxy is made on the client side, rather than a copy.
See http://java.sun.com/javase/6/docs/technotes/guides/rmi/faq.html#firewall
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If the servers code is in your hand you could also restrict RMI to use a predifined port by providing a custom RMISocketFactory as described here: http://insidecoffe.blogspot.com/2012/02/firewall-friently-rmi-port-fixing.html
(Note specially the hint that it may cause problems if you use JMX in parallel)
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