Transcript SM2215 Genres Part 3 – The Internet

SM2215 Genres
Part 3 – The Internet
Mark Green
School of Creative Media
Introduction
 The
Web is the main form of Internet
media, but there are other forms
 Many of these forms are accessed through
a browser, so they are often confused with
the Web
 Look at some of the more popular forms
and their artistic, cultural and political
applications
Streaming Media
 Started
with compression
 Compressed video and audio, more
efficient to send over network, basic file
transfer
 If compression is good enough can
transfer in real time, a second of media
can be transferred in less than a second
 Only need to reconstruct it
Streaming Media
 Two


things are required:
Real time transfer
Real time reconstruction
 The
un-compression algorithm must be
fast enough to run in real time
 Be able to transmit and reconstruct the
signal at the same rate it should be played
Streaming Media
 Two


modes of operation:
On demand
Live
 On
demand: client connects to server and
requests a particular media clip
 Server then streams the clip to the client
 Only two parties involved in the transfer
Streaming Media
 Live:
server is broadcasting a live event to
a group of clients
 Event could be an Internet radio station or
a sports event
 The media hasn’t been previously
recorded, it is being sent as it is generated
 many clients getting the same content at
the same time
Streaming Media
 On
demand is easier and can be higher
quality
 Can preprocess the media, just transmit to
single client when requested
 Can adjust quality to available network
bandwidth, tune the transmission to what
the network can deliver
Streaming Media
 Live
involves the server sending a real
time stream to many clients
 Server must compress the stream as it
occurs in real time
 Then needs to send to all of the clients
 Can require much more bandwidth and
can’t tune the transmission to each client’s
network connection
Streaming Media
 Live
broadcasts can go to thousands of
clients, can’t have a separate connection
for each client
 Multicasting allows server to send one
copy, automatically routed to the clients
that want it
 Much more efficient use of network
bandwidth
Pirate Radio
 Unlicensed


radio stations:
No government control
No royalties paid to record companies
 Quite
an old idea, based on low power
transmitters that are easy to move
 Most countries will try to shut down pirate
radio stations, often work off shore
Pirate Radio
 Why?




Political message not popular with current
government
Music that isn’t popular on commercial radio
Grass roots access to media
Fun
 Transmitter
based can be dangerous and
difficult, moving to network radio
Pirate Radio
 Stream
from a server, could be a
connection from a web page, or IP
address distributed by email
 Server can be in different country, or
moved regularly to prevent blocking
 Harder to find and shut down than
transmitter based stations
Web Radio
 Regular
radio has limited range, can only
reach local listeners
 must be able to get large audience from
local area
 may not be possible for some types of
music
 music styles vary from one part of the
world to another
Web Radio
 Web
radio removes regional restrictions,
much larger population to draw on
 two main implications:


can build up audience for less popular styles
reach listeners outside of normal geographical
area
 can
be exposed to a wider range of
cultures
 can send our culture further
Web Radio
 Issues:



are advertisers willing to pay? Most radio ads
are local, need to look at global audience
royalties, where are they paid, who gets
them?
How do we measure audience size, this is
important for advertising and royalties
 how
should web radio be funded? Is
advertising the right model
Business Models
 How
do we make money on internet
services?
 Advertising is the broadcast / print media
solution, is it best for the internet?
 Many sites use various forms of
advertising and click throughs
 seems to work for a few very popular sites
Business Models
 Problems




with advertising:
software to remove adverts, not sure that user
ever sees them
developing a negative image, too much will
chase users away
hard to measure number of viewers, standard
charging mechanism for adverts
how do local advertisers fit into the picture?
Business Models
 Other



possible models:
sponsorship, have a small number of large
companies sponsor the web site, minimal
advertising
subscription, each viewer pays a certain
amount per year, best if voluntary
donations and annual appeals, has worked
well for public broadcasting in North America
Peer to Peer
 Most
Internet services are based on the
client-server model
 There is a server that contains the
information, multiple clients connect to it to
receive information
 The server is the central resource, stores
all of the information
Server Model
Server
client
client
client
client
Server Model
 Encourages
broadcast, central server has
all the content, sent to the clients on
request
 clients have no content
 the server controls the interaction, the
client plays a more passive role
Peer to Peer
 In
the peer to peer model there is no
central server, or its plays a minimal role
 The clients are directly connected together
and share information
 More of a two way flow of information, no
centralized coordination, no special nodes
in the system
Peer to Peer Model
client
client
client
client
client
Peer to Peer Model
 More
of a communications model
 one node doesn’t have control over the
content, no monopoly on content
 all nodes contribute to the content
 applications tend to concentrate on
communications, tend to be real time
interactive
How is it Used?
 Most
high profile use is file sharing,
originated with Napster, but there are other
applications:



file sharing
resource sharing
communications
File Sharing
 Napster
allowed people to exchange MP3
files, share their music files with others
 each user had a library of music files that
they could share
 problem was finding who had what file
 Napster used a centralized model, a
server maintained a list of who had which
files
File Sharing
 To
find a file, send a message to the
server
 server responds with list of people with the
files
 connect to one of these computers,
directly transfer the file from that computer
 Napster server never stored any MP3 files,
just served as a directory or search engine
File Sharing
 Napster


system had two benefits:
no storage of MP3 files meant they were not
directly guilty of copyright infringement
did not need all of the disk space to store all
the files
 Napster
still had major legal problems, but
formed the model for future systems
File Sharing
 Napster
wasn’t the first file sharing
system, Usenet started in 1979, used for
both messaging and file sharing
 based on newsgroups, each group is a
sequence of messages on similar topics
 newsgroups forms a hierarchy, but rarely
more than 3 or 4 levels
File Sharing
 New
newsgroups are formed by a
democratic process
 group is proposed and anyone with an
email account can vote on its creation
 if vote passed, newsgroup is created
 in the alt hierarchy anyone can create a
new group, a form of organized anarchy
File Sharing
 Usenet
has no central server, no central
storage
 every system on Usenet exchanges
messages with the systems it is directly
connected to, messages spread over
Usenet
 message header ensure messages aren’t
sent back to systems that already have
them
File Sharing
 Gnutella
and similar systems get around
one of Napster’s problems
 no central server with file directory, the
directory is shared by all the clients
 each client maintains list of other Gnutella
clients it knows about, can change
dynamically
File Sharing
 To
find a file, send a message to other
clients on our list
 if a client has the file, responds with its
address, otherwise it passes the request
on to all the the clients it knows of
 eventually will get responses with the
clients that have file (if it exists anywhere
on the network)
Resource Sharing
 Can
share more than files, can also share
computer time
 most of the time home computers aren’t
used, they are idle, could be used for other
purposes
 the basic idea behind the SETI@home
program
Resource Sharing
 SETI
is the search of extra terrestrial
intelligence
 based on recording signals from radio
telescopes and then trying to find
intelligence in them, some form of
communications
 requires very large amounts of
computation, not available to researchers
Resource Sharing
 SETI@home
uses home computers to
process the data
 home computer requests a small part of
the data, analyzes the data, and sends the
results back to central site, repeats
process
 large network of home computers is more
powerful than largest computers, and its
free
Resource Sharing
 Possible
model for funding network
services
 provide a few hours of computing time in
exchange for a service, i.e. web radio
 some large computations are
commercially important, companies will
pay for time
 sponsor services in exchange for
computations
Communications
 Instant
messaging and similar systems
provide a form of peer to peer
communications
 most of these systems are at least partially
server based, but they support
communications between two or more
clients
 in real time they can be peer to peer
Communications
 Why



do they need a server?
Need to know how to contact other users, can
roam between computers
need to know who is online
store messages for users who aren’t currently
online
 except
for last point, the server can play a
rather minor role
Communications
 Without
message storage, server only
needs to know who is connected and how
they can be contacted
 this could probably be distributed in the
same way as Gnutella, broadcast requests
to known clients, etc
 once friend is found directly connect to
their client
Communications
 Most
instant messaging systems are
commercial:


server based, can keep track of users,
charging is possible
proprietary protocols, can only talk to people
on the same system, can’t send messages
between systems
 most
systems are limited to text
Communications
 Jabber:
Open source protocol for instant
messaging
 originally developed as a bridge between
other instant messaging systems
 Jabber can support other media, such as
sound and video, not clear whether any of
the standard clients support this
 could develop custom clients for art
projects
Social and Political Issues
 Sometime
a political agenda associated
with these services
 political commentary in countries with tight
media control
 expression of unpopular opinions, possible
legal or economic problems associated
with views
Social and Political Issues
 Two


main concerns:
censorship of online information sources
anonymity for controversial messages
 with
a central server its very easy to block
messages and web content, domain name
and IP are well known
 with many peers this isn’t possible, IP can
change dynamically from day to day
Social and Political Issues
 Only
problem is knowing the current IP
address, this can be done through email or
through a broadcast mechanism like
Gnutella
 anonymous mailing systems make it
impossible or difficult to trace origin of
messages, can be used to hide the
author’s identity
Social and Political Issues
 With
regular email can trace the author,
can trace message back to machine
where the message was created
 to send an anonymous message, send to
a special server, hides sender’s identity
 can even reply to anonymous email,
through the same server that sent it
Social and Political Issues
 Can
be used to protect people with
important, but sensitive messages, assist
political groups, etc
 but, there is a negative side, same
technology can be used by terrorists and
criminals
 can also be used to hide their activities,
becomes a moral and ethical issue
Artistic Applications
 Can
we use this technology in an artistic
way?
 There are at least two applications:


broadcast, distribution of art work
collaboration and performance
 Napster
used to distribute commercial
MP3s, why not use it to distribute other art
works?
Artistic Applications
 Could
use file sharing systems to
distribute video and music pieces
 no need to have formal distribution
channels, good for new artists and less
popular art forms
 avoid issues of censorship and artistic
tastes
Artistic Applications
 Instant
messaging for artistic purposes?
 Be able to collaborate in real time on
creation of artistic pieces
 easy to see with text, but this might not be
the most interesting
 adding sound and video gives a much
richer environment, could use the same
technology