Figure 2 shows how the components
of HYDRANET interact. We observe
from the figure that Host 128.142.222.80 is a host server. The
Web service (realized by the httpd daemon) on Host 192.20.225.20
is replicated on the host server, where it is realized by the a_httpd
replica daemon. Whenever the process on the host server binds to a TCP
or UDP port, the host server and the redirectors are informed, and the
redirector tables updated. The HTTP requests from Client C are routed
to the origin host. The same requests from Client A are intercepted
by the redirector, which happens to be on their route, and which was informed
earlier that the nearest Web port for host 192.20.225.20 is located
on host server 128.142.222.80. The requests are routed accordingly.
Client B's requests for the telnet service are not rerouted by the
redirector, but are forwarded to the origin host; the redirector does not
have an entry for the telnet port of host 192.20.225.20. We note
that neither the clients nor the non-participating servers are affected
by this scheme. We will see in Section 5
that even participating servers need not be directly affected.
