These traces contain records of the HTTP requests and user behavior of a
set of Mosaic clients running in the Boston University Computer Science
Department, spanning the timeframe of 21 November 1994 through 8 May 1995.
During the data collection period a total of 9,633 Mosaic sessions were
traced, representing a population of 762 different users, and
resulting in 1,143,839 requests for data transfer.
Trace logfiles contain the sequence of WWW object requests
(whether the object was served from the local cache or from the
network). Each log file name contains a user id number,
converted from Unix
UIDs via a one-way function that allows user IDs to be compared for
equality but not to be easily traced back to particular users. The file name
also gives the machine on which the session took place, and
the Unix timestamp when the
session started. Boston University is located in the United States Eastern
For example, a file named con1.cs20.785526125 is a log of a
session from user 1, on machine cs20,
starting at time 785526125 (12:42:05 EST, Tuesday, November 22, 1994).
Each line in a log corresponds to a single URL requested by
the user; it contains the machine name, the timestamp when the request
was made, the user id number, the URL, the
size of the document (including the overhead of the protocol) and the
object retrieval time in seconds (reflecting only actual communication time,
and not including the intermediate processing performed by Mosaic in a
multi-connection transfer). An example of a line from a condensed log
cs20 785526142 920156 "http://cs-www.bu.edu/lib/pics/bu-logo.gif" 1804 0.484092
Lines with the number of bytes equal
to 0 and retrieval delay equal to 0.0 mean that the request was
satisfied by Mosaic's internal cache.
To collect this data we installed an instrumented version of Mosaic in
the general computing environment at Boston University's Computer
Science Department. This environment consists principally of 37
SparcStation 2 workstations connected in a local network, which is
divided in 2 subnets. Each workstation has its own local disk; logs
were written to the local disk and subsequently transferred to a central
We began by collecting data on a subset of the workstations
only, while testing our data collection process. This period lasted
from 21 November 1994 until 17 January 1995.
When we were statisfied that data collection was occurring correctly, we
extended the data collection process to include all
workstations; data collection then took place until 8 May 1995.
Since Mosaic ceased to be the dominant browser in use by early March
1995, the most representative portion of the traces are those covering
the period 21 November 1995 through
28 February 1995.
The user IDs in these logs have been renumbered to protect privacy.
These logs were collected by the members of the
research group at Boston University.
Mosaic was instrumented by Carlos Cunha (firstname.lastname@example.org). When
referring to the use of these traces in published work, please cite
Characteristics of WWW Client Traces,
Carlos A. Cunha, Azer Bestavros and Mark E. Crovella,
Boston University Department of Computer Science,
Technical Report TR-95-010, April 1995.
The traces may be freely redistributed.
Available from the Archive as a
gzip compressed tar file (13.8 MB; 101 MB uncompressed).
Traces In The Internet Traffic Archive.