Two-way remote object communication method over firewall

摘要

In object-oriented programming, mutual referencing among objects plays a crucial role. In order to implement mutual referencing in distributed object environments, the communication path among hosts, on which the remote objects to be mutually referenced reside, should be established unconditionally. Unfortunately, such an assumption is not practical in real network environments such as the Internet, because in many cases firewalls and IP network address translators (NAT) restrict the TCP/IP connections that can be established to "one-way". This paper presents a solution to this problem by using the Java RMI custom socket feature. The method we present solves the problem by seamlessly translating a two-way remote object invocation into one-way TCP/IP connection establishment. Once translated, the remote objects can successfully communicate over the firewall.