Since Jolokia uses HTTP (or HTTPS) for its transport protocol, it plays nicely with even complex firewall setups. For the client within a firewall it is easy to access Jolokia agents outside over an HTTP proxy, even over multiple hops. Also since HTTP is such a widely adopted protocol, it is much better accepted than RMI, which is mostly specific to the Java world (or CORBA world if using IIOP). Hence chances are much higher to get an agreement with the firewall policies in place.

Since HTTP use a single, fixed port it is easy to let Jolokia communicate through an SSH tunnel, too. This is not easy with the standard JSR-160 protocol RMI, which uses random ports. There are solutions to use fixed port number, but they are horribly complicated.

With Jolokia’s proxy mode there are even more options to let the Java servers without any agent within the firewall to be reached from the outside over HTTP.

There has been efforts to put JSR-160 on a different protocol stack, but they are either not a standard solution, requiring a special client setup (like MX4J) or seemed to have been dropped (WS connector which uses SOAP had its last pre-release in October 2008). Up to now, the only solution which allows for a smooth, firewall friendly setup is a JMX Bridge (or Proxy), like Jolokia.