After two days research. result is:
1. java-JAVA, RMI or RMI-IIOP is preferred within inranet.
2. Eclipse ECP now also develop an implementation based on socket(TCP/IP),
But it is named after R-OSGI.
3. Hessian support cross firewall service invocation. It is supposed to be
good balance on performance and usablity.
4. Tuscany now support RMI and other transport. Hessian implementation just
a patch. Watch https://issues.apache.org/jira/browse/TUSCANY-2748
5. River project and Tuscany project both have intention on Distributed OSGI.
Watching...