WebMelody: Sonification of Web servers
Maria Barra Tania Cillo Antonio
Umberto Ferraro Petrillo Alberto Negro
Dipartimento di Informatica ed Applicazioni
Università di Salerno
Baronissi (Salerno) 84081 -- Italy
1 - Introduction
WWW servers are growing in size, complexity and workload. HTTP
requests are logged to files and, later, analyzed by the Webmaster so
that the information can provide useful hints on tuning and/or
malfunctioning in the WWW server. These log files are huge and the
analysis is greatly helped by software programs that perform
statistics on such huge amount of data, grouped by several criteria
(time, location, Internet domain name, etc.).
Monitoring a WWW server is, usually, an off-line activity: performed
on a regular basis, or prompted by evident malfunctioning. We argue
that it is important to provide an effective, efficient way to monitor
in real-time the behaviour of the server.
In this paper we present a novel technique to monitor the behaviour of
the WWW server by associating sounds to events describing the server
activity. The sounds are carefully chosen so that they form a
"natural" background music: music should not engage the listener and
should not disturb his/her daily activities. Our scenario is that
"server music" is going to substitute (by masquerading) the background
noises (normally present in the workplace and not recognized) as a
low-volume radio does.
2 - Our Technique
Using nonspeech audio to convey information (or sonification), is
particularly useful when there is an abudance of data to be
considered. The "ticking" of a Geiger counter as well as sonar is well
known since decades as well as using sounds to enable blind scientists
to examine experimental data via an auditory presentation ([Lunney et
al. (1990)]) or to troubleshoot intermittent network connections [Muuss].
WWW servers generate log files with information about each single HTTP
request and the response. Many servers allow log data to be stored in
a proprietary format (like Apache module mod_log_config) and
proposals like the Extended Log File Format are studied [Hallam-Baker (1999)] to add an extensible logging
Logfiles grow quickly to hundred of megabytes, making the analysis
possible only with off-line tools (known as Log
Analyzers) to present log data in a synthetic and coherent shape.
We propose to use sonification as a technique to monitor the correct
functioning of the WWW server. The main positive characteristic of
our technique is that it allows, in real time, to "feel" several
server parameters at once while it is non-obtrusive with respect to
normal daily activities. At the same time, sonification can be an
efficient solution to allow on-line monitoring of the large amount of
log data that are available.
The technique to use sounds to express and interpret (raw)
data is non-obtrusive: the webmaster can perceive the server behavior
and execute other tasks at the same time. The webmaster can have this
sound as "background music" acting as a support for providing
auxiliary information. This information can quickly redirect the focus
of the Webmaster to the problem whenever needed so that he can take
Sonification allows to convey an interpretation of a large amount of
data, since all requests are analyzed and, eventually, "played" in
real-time. In this way, while monitoring the behaviour, the webmaster
can avoid to rely exclusively on off-line analysis of the log files
that provide, indeed, accurate and entrusted statistics but that are
not timely. Finally, sonification could join together the manyfold
aspects of a Web server that one wants to monitor.
We envision several real-life situations where a real-time, and still
non-completely absorbing, tool can help the Webmaster. By monitoring
the WWW server behaviour via sonification the Webmaster can:
The sonification technique (and our tool WebMelody) is not meant to
substitute off-line analysis but is, instead, devoted to ideally
complement the log analyzers by giving the immediate perception of
what is going on to the webmaster. Then, if necessary, the webmaster
can study logfiles with the log analyzers to pinpoint problems and
early detect Denial of Service attacks;
early determine that the server does not work;
recognize load peaks and have some feeling about possible
explanations of these;
discern among the different types of requests: for
example, determining where the requests come from, or
discriminating accesses by different agents, etc.
monitor accesses to restricted (by user authentication)
recognize the different error types and the
HTTP method of the request.
Part of our research was devoted to find an adequate musical
representation of the behaviour of a WWW server.
Our goal was to provide sounds that go beyond the simple alarms,
trying at the same time to offer an aestethic connotation to sounds
that lay on the borderline between music and background noises. The
WebMelody prototype is provided with sounds
with such characteristics that allow to listen to the
music for a long time without diverting the user from the focus of
Our musical work is based on the experiences of this century in the
field of the "applied music" such as Luigi Russolo (early XX century's
futurism), Edgar Varese (1958) and (more recently) John Cage.
In WebMelody, we tried to avoid to configure harmonic-tonal
fields as well as rithmic references that are potentionally able to
attract the focus of the users by leveraging on their mnemonic and
musical (personal) capabilities.
3 - WebMelody: the architecture
WebMelody is a distributed, versatile (easily configurable) and
portable system that allows WWW server (Apache) monitoring via
sonification. The architecture of WebMelody consists of three
components: the sonification Apache modules
mod_musical_log and mod_counter, the
Collector server and the WebPlayer application.
The sonification modules are inserted into an Apache WWW server and
are responsible for sending data to the Collector upon arrival and
serving of HTTP requests. These modules can filter events as specified in the appropriate configuration directives of the Apache WWW server.
The Collector is a Java application that
works as middle layer: it buffers the events provided by the Web
server(s), parses them and can monitor load and throughput of the Web
server as well as analyze the events that must be played only if a
treshold is passed. Then, a command string specifing the sounds to be
played is produced and then sent to the WebPlayer(s) that holds the
sound files corresponding to each event.
More details on the WebMelody system can be found at the Project Home
Page at http://isis.dia.unisa.it/SONIFICATION. The
full paper describing the architecture in greater detail is at http://isis.dia.unisa.it/SONIFICATION/sonification.html
as well as an MP3 demo (http://isis.dia.unisa.it/SONIFICATION/web.mp3).
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