The RealTime Conferencing Applications

1
The Real-Time Conferencing Applications

• Classification
• Network News (NNTP)
• P2P Collaborative applications
• Instant Messaging
• Real-Time Collaboration
• Netiquette

2
P2P Collaborative Applications

• For remote real-time human collaboration
• Instant messaging, virtual meetings, shared
  whiteboards, teleconferencing, tele-presence
• E.g., talk, IRC, ICQ, AOL Messenger, Yahoo!
  Messenger, Jabber, MS Netmeeting, NCSA Habanero,
  Games

3
Classification of Textual Conferencing

• According to the relative timing
• Asynchronous or
• Synchronous
• According to the number of participants
• One to One
• One to Many
• Many to Many

4
Network News, Newsgroups

• Network News Transfer Protocol (NNTP)
• Predecessor UUCP
• Components
• News Transfer Agency (NTA)
• News Server
• News Reader Client Software
• E.g. Pine, trn, tin, Pnews, Netscape Navigator,
  etc.

5
NNTP Operation

• To acquire recent articles, an NNTP client must
  first establish a TCP connection with port 119 on
  one of its newsfeeds
• After the connection has been established, the
  client and server communicate using a sequence of
  commands and responses
• These commands responses are used to ensure
  that the client gets all the articles it needs,
  but no duplicates

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NNTP Commands
7
Names of Some Top-Level Newsgroups and Their
Topics
8
Names of Some Newsgroups in the Field of
Informatics and Their Descriptions
9
Real-Time User Communication

• Chat in written form (textual conferencing)
• Internet Relay Chat (IRC)
• ICQ
• Instant Messaging
• Internet based telephoning

10
Synchronous choices

• Talk, n-talk, y-talk
• ICQ
• IRC, Netmeeting
• See http//www.irchelp.org/irchelp/altircfaq.html
• Web-based synchronous tools, chats
• Stand alone, CGI-based, and Java-based
• See http//www.2meta.com/chats/info/
• White-boards

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Instant Message Technologies
ICQ Jabber (http//www.jabber.org/) MSN
(Microsoft Messenger) Yahoo! Messenger GMAIL-based
Messenger
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ICQ Instant Messaging

• Released in November 1996
• Allows users to be notified when their friends
  come online
• Users can send messages to their friends
  (instant messaging)
• Also allows users to exchange files

www.icq.com Main ServerUser List
User A
User B
13
Short history of ICQ

• The company Mirabilis was founded in 1996
• their field of focus was to be peer-to-peer
  communication through the Internet
• In the same year they launched ICQ as their first
  product
• It was an instant messenger for use on the
  Internet
• A lot of others were to come, but ICQ was the
  first one to enter the market
• Its main features included
• The ability to show the user when his friends are
  online (connect to the ICQ-server)
• Invoke online real-time peer-to-peer
  communication in different ways (message, games
  etc)
• An address-database for the users friends and
  ICQ-contacts
• In 1998 Mirabilis was bought by AOL, a company
  that earlier had realesed an instant messenger
  themselves
• ICQ had although proved to be more successful
  than the AOL instant messenger, and the existence
  of ICQ was not immediately threatened

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ICQ today

• Ever since the first version released in 1996 ICQ
  has focused on the P2P (peer-to-peer)
  communication. The communication possibilities
  have although expanded, and includes in the
  latest beta-version ICQ2000b among other
  functions the following
• Instant messaging system
• Realtime chat-function
• Phone via the Internet (PC-PC, PC-phone
  phone-phone)
• SMS service
• Direct filetransfer possibilites between two
  users
• ICQ is available for many different operating
  systems today, including a Java-version and also
  a version for the Palm OS.
• Main competitors include AIM, MSN Messenger and
  the Yahoo! Messenger

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Visit Sharons Homepage, or Send her a sms
ICQ Also a Community
Splitting of the Contact list according to their
current ICQ-status

• User status
• Sharon has sent you a message
• Daniel has birthday
• MOM has left an away message
• Z-home is not available

Shortcut bar
ICQ status I am currently online -connected to
the ICQ network
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The User Menu Here you can choose between all
the different possibilities to contact The user,
or change the current settings for this
particular user
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The technical facts

• To communicate with the server, ICQ uses UDP. In
  the Client-Client case both UDP and TCP are used.
  Inside the UDP packets, the messages themselves
  are created according to the so called
  ICQ-protocol.
• If you are interested in the details, try the
  following links
• The ICQ Protocol Site (English, French, German,
  Russian and Spanish)
• http//www.d.kth.se/d95-mih/icq/
• The ICQ Hacking Page (English)
• http//www.algonet.se/henisak/icq/
• For general information, visit http//www.icq.com/

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P2P Collaborative Applications

• Magi
• Groove
• Jabber

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Collaboration

• Tap into knowledge
• Leverage expertise at the
  edges of organization
• Each additional member increases the networks
  value
• Outsourcing
• Collaborative Development Manager

20
Groove

• Groove is a collaborative P2P system
  (http//www.groove.net)
• It is mainly targeted to Internet and intranet
  users, although it can also be used on mobile
  devices, such as PDAs, mobile phones, and tablets
• It is intended to enable communication, content
  sharing, and tools for joint activities

21
Internet Relay Chat (IRC)

• Definition of IRC
• textbased teleconferencing system using TCP/IP
• multi-user, multi-channel system
• offers the possibility to talk to other users
  around the world in realtime

22
History of IRC

• Summer 1988 Jarrko Oikarinen wrote the first IRC
  client and server at the University of
  Oulu/Finland
• Middle of 1989 40 servers worldwide - release of
  ircII
• July 1990 avergage of 12 users on 38 servers
• August 1990 birth of EFnet
• October 1992 start of Undernet
• May 1993 Request for Comments (RFC) 1459
  presented to the public
• July 1994 birth of Dalnet
• July 1996 split of the EFnet the European
  servers formed the IRCnet
• January 1998 start of a initiative (IETF-IRCUP)
  to create a new RFC and to set up a new standard
  for all IRC-networks. The project was cancelled.

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IRC networks
24
Basic IRC Commands

• Basic Commands (selected)

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IRC Channels

• Real-time chat - text-based conferencing
• There is an IRC channel dedicated to the World
  Wide Web
• This channel is named www
• IRC channels allow Internet users around the
  world to discuss topics in real-time

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Architecture of IRC

• An IRC network is defined by a group of servers
  connected to each other
• A single server forms the simplest IRC network
• The only configuration allowed for IRC servers is
  that of spanning tree where each server acts as a
  central node for the rest of the network it sees
• The IRC protocol provides no mean for two clients
  to directly communicate
• All communication between clients is relayed by
  the server(s)

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Sample Small IRC Network
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IRC Protocol Services

• The next services are offered by the IRC Protocol
• The combination of these services allow real-time
  conferencing
• Client Locator
• Message Relaying
• Channel Hosting and Management

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Client Locator

• To be able to exchange messages, two clients must
  be able to locate each other
• Upon connecting to a server, a client registers
  using a label which is then used by other servers
  and clients to know where the client is located
• Servers are responsible for keeping track of all
  the labels being used

30
Message Relaying

• The IRC protocol provides no mean for two clients
  to directly communicate
• All communication between clients is relayed by
  the server(s)

31
Channel Hosting and Management

• A channel is a named group of one or more users
  which will all receive messages addressed to that
  channel
• A channel is characterized by its name and
  current members, it also has a set of properties
  which can be manipulated by (some of) its members
• Channels provide a mean for a message to be sent
  to several clients
• Servers host channels, providing the necessary
  message multiplexing
• Server are also responsible for managing channels
  by keeping track of the channel members

32
IRC Concepts

• In the following it is described how different
  classes of messages are delivered
• One-to-one communication
• One-to-many
• One-to-all

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One-To-One Communication

• Communication on a one-to-one basis is usually
  performed by clients, since most server-server
  traffic is not a result of servers talking only
  to each other
• To provide a means for clients to talk to each
  other, it is required that all servers be able to
  send a message in exactly one direction along the
  spanning tree in order to reach any client.
• Thus the path of a message being delivered is the
  shortest path between any two points on the
  spanning tree

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Examples of One-to-One Communication

• Example 1 A message between clients C1 and C2 is
  only seen by server S1, which sends it straight
  to C1 and C2, respectively
• Example 2 A message between clients C1 and C3 is
  seen by servers S1, S2, S3 S4
• No other clients or servers are allowed see the
  message
• Example 3 A message between clients C2 and C7 is
  seen by servers S1, S2, S3 S6, only

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One-To-Many Communication

• The main goal of IRC is to provide a forum which
  allows easy and efficient conferencing (one to
  many conversations)
• IRC offers several means to achieve this, each
  serving its own purpose
• To a channel
• To a host/server mask
• To a list

36
To a channel

• In IRC the channel has a role equivalent to that
  of the multicast group
• Their existence is dynamic
• Actual conversation carried out on a channel must
  only be sent to servers which are supporting
  users on a given channel
• Moreover, the message shall only be sent once to
  every local link as each server is responsible to
  fan the original message to ensure that it will
  reach all the recipients

37
Examples of One-to-Many Communication

• Example 1 Any channel with C1 in it gt Messages
  to the channel go to the S1 and then nowhere else

• Example 2 Two clients in a channel gt All
  messages traverse a path as if they were private
  messages between the two clients outside a
  channel
• Example 3 C1, C2 C3 in a channel gt All
  messages to the channel are sent to all clients
  and only those servers which must be traversed by
  the message if it were a private message to a
  single client
• If C1 sends a message, it goes back to C2 and
  then via S2, S3 S4 to C3

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To a host/server mask

• To provide with some mechanism to send messages
  to a large body of related users, host and server
  mask messages are available
• These messages are sent to users whose host or
  server information math that of the mask
• The messages are only sent to locations where
  users are, in a fashion similar to that channels

39
To a list

• The least efficient style of one-to-many
  conversation is through clients talking to a
  list of targets (client, channel, mask)
• How this done is almost self explanatory
• the client gives a list of destinations to which
  the message is to be delivered and
• the server breaks it up and dispatches a separate
  copy of the message to each given destination
• This is not as efficient as using a channel since
  the destination list may be broken up and the
  dispatch sent without checking to make sure
  duplicates arent sent down each path

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One-To-All Communication

• The one-to-all type of message is better
  described as a broadcast message, sent to all
  clients or servers or both
• On a large network of users and servers, a single
  message can result in a lot of traffic being sent
  over the network in an effort to reach all of the
  desired destinations
• For some class of messages, there is no option
  but to broadcast it to all servers so that the
  state information held by each server is
  consistent between servers
• Its types
• Client-to-client
• Client-to-server
• Server-to-server

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Client-to-Client

• There is no class of message which, from a single
  message, results in a message being sent to every
  other client

Client-to-Server

• Most of the commands which result in a change of
  state information (such as channel membership,
  channel mode, user status, etc.) must be sent to
  all servers by default
• This distribution shall not be changed by the
  client

42
Server-to-Server

• While most messages between servers are
  distributed to all other servers, this is only
  required for any message that affects a user,
  channel or server
• Since these are the basic items found in IRC,
  nearly all messages originating from a server are
  broadcast to all other connected servers

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Architecture Related Problems of IRC (1)

• Scalability
• This protocol does not scale sufficiently well
  when used in a large arena
• The main problem comes from the requirement that
  all servers know about all other servers, clients
  and channels and that information regarding them
  be updated as soon as it changes
• Reliability
• As the only network configuration allowed for IRC
  servers is that of a spanning tree, each link
  between two servers is an obvious and quite
  serious point of failure

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Architecture Related Problems of IRC (2)

• Network Congestion
• Due to the spanning tree architecture the IRC
  protocol is extremely vulnerable to network
  congestions
• This problem is endemic (local), and should be
  solved for the next generation
• if congestion and high traffic volume cause a
  link between two servers to fail, not only this
  failure generates more network traffic, but the
  reconnection (eventually elsewhere) of two
  servers also generates more traffic
• In an attempt to minimize the impact of these
  problems, it is strongly recommended that servers
  do not automatically try to reconnect too fast,
  in order to aggravating this situation

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Architecture Related Problems of IRC (3)

• Privacy
• Besides not scaling well, the fact that servers
  need to know all information about other
  entities, the issue of privacy is also a concern
• This is in particular true for channels, as the
  related information is quite a lot more revealing
  than whether a user is online or not
• Security considerations
• Asides from the privacy concerns, security is
  irrelevant

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Software Implementations References

• Software implementations
• ftp//ftp.irc.org/irc/server
• ftp//ftp.funet.fi/pub/unix/irc
• ftp//coombs.anu.edu.au/pub/irc
• References
• www.irchelp.org/irchelp/
• www.newircusers.com
• www.contactor.se/dast/irc/history.html

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Netiquette issues
Media richness (paucity), self presentation,
flaming and social control issues

• Rule 6 Share expert knowledge
• Rule 7 Help keep flame wars under control
• Rule 8 Respect other people's privacy
• Rule 9 Don't abuse your power
• Rule 10 Be forgiving of other people's mistakes

• Rule 1 Remember the Human
• Rule 2 Adhere to the same standards of behavior
  online that you follow in real life
• Rule 3 Know where you are in cyberspace
• Rule 4 Respect other people's time and bandwidth
  
• Rule 5 Make yourself look good online