From: Honghai Liu (liu789_at_hotmail.com)
Date: Mon Feb 02 2004 - 10:13:38 PST
Reviewer: Honghai Liu
Grapevine is the distributed system that provides messaging, naming, authentication and resource location service
in the early Internet age. And Grapevine was supposed to achieve high availability, system transparency to the users,
scalability, easy operation and fast recovery from the failure of servers.
From the implementation of this mail system, we can see it's quite similar to modern E-mail system. It provides
naming or location of user and group to distribute messages. And it also provides storage for users to retrieve
mails from either local server or remote servers.
It is interesting to see that it is much more difficult to make modification to a live system like Grapevine, and most
of the changes to the system were to fix unexpected problems in practice rather than to add new functionality to
the system.
One of the goals of Grapevine was the ability to increase system capacity over a large range by adding more
servers of fixed power, rather than by using more powerful servers. However, I don't think the strategy was
effective because of two reasons: First, the naming service(registrar) was flat, and with the growth of the users
and groups in the system, the traffic loads increased much more than a linear function. I would image a hierarchy
approach could have proven been more scalable. Second, the servers were deployed with few regards to the
different reliability and performance of links between different sites. More consideration should have been given
on how to confine the network traffic locally rather than let them travel over a slow telephone links.
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