About LSAM Environmental Analysis
The goals of the LSAM environmental analysis component are: (1) create
and insert algorithms into web servers that select files that are
advantageous to transmit to proxies via a multicast group, and (2)
insert into proxies an algorithm that determines whether to join
specific server multicast groups.
Loosely stated, candidate files for multicasting by a server should be
requested repeatedly over a considerable interval. This selection
could be done by hand in special cases. For example, to select a
group of URLs that become hot due to a popular current event and
deslecting it when the event became less popular. Ideally however,
the selection procedure should be automated. Determining what that
automated procedure should be is a near-term goal for LSAM.
In the absence of special hints given by a server administrator, an
automated selection procedure has only the retrieval history with
which to make a decision. Using that historical information the
procedure must be able to successfully identify server files that are
likely to be fetched frequently in future. However, other than
perhaps a few key home page files, there is no reason to expect
necessarily that files exhibiting such behavior exist in a server.
Closely related to the problem of selecting candidate files for
multicasting is the question posed to a proxy when it is presented with
the option of joining a server's multicast group. Would joining be
advantageous to that proxy?
To determine whether or not a successful automated selection procedure
could be created and how successful it might be, a package of log
analysis software was written. This package is used to collect
statistics on frequency of URL retrieval across long intervals.
The questions that we are examining are: Does past URL retrieval
history indicate the likelihood of future retrieval? If it does, what
algorithms are effective at selecting URLs as candidates for a
Page maintainer: Ted Faber
Last modified: Mon Jan 6 10:48:20 1997
Copyright © 1996 by USC/ISI