Instant messaging

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Instant messaging (IM) is a primarily text-based application in which users exchange short messages in real time. It is considered a structured peer-to-peer (P2P) application, with a server or servers providing a coordination function between the clients but the message flow occuring directly client-to-client.

General Description And Operation

To participate in IM, the user needs an IM client which they can load into their computer system, cell phone, or other intelligent device. They also need an account in an IM service, and there are many available on the Internet, including Yahoo Instant Messenger, AOL Instant Messenger (AIM), Skype, Windows Live Messenger (Microsoft), and ICQ (pronounced I seek you). Once the user has an account and password, they can initiate their client and enter the account name and password. The client contacts the IM server and authenticates with it. The server now knows this client is online. The server also maintains the user's buddy list and knows the status of each of these users. This is reported to the client and the information is displayed for the user.

The user typically has some degree of control over how their status is made available to others. They can elect to share their status with no one (i.e., invisible), only with members of their buddy list, or with everyone. They can choose to receive messages from anyone, only members of their buddy list, or no one (i.e., unavailable). The latter is typically done only temporarily. Many IM clients also monitor computer usage (i.e., has the mouse or keyboard been used recently) and automatically changes the status of the user if their are periods of inactivity. Again, this information sharing can typically be controlled by the subscriber. All of this information is considered a form of telepresence.

When a client wishes to communicate with another member, the server provides the information about how to reach the other client, and may also initiate the conversation between the two devices. Once the connection is established, messages usually flow directly between the two clients. The server may or may not be kept in the loop during this process.

Advanced IM Capabilities

Another form of instant messaging is found as part of cell phones and is known as the Short Message Service (SMS) or simply text messaging. Today, most IM service providers implement support for interworking between SMS and IM systems, so one can IM a cell phone from a computer or receive an IM on a computer that originated from a cell phone as an SMS message.

Modern IM systems have additional advanced capabilities. Most feature a click to talk capability, making it possible for two people to speak to one another if they prefer doing that to typing messages. Many clients also have built in file transfer capabilities, message archiving, and conference chatting. Increasingly, the applications are incorporating links to the PSTN making it possible to people to initiate and accept telephone calls from their IM clients - which is rapidly blurring the distinction between voice-enable IM and IP telephony.

IM Protocols and Conventions

Instant messaging

Although RFCs exist that define the communications model for IM, the actual protocols used and the sequence of the messages are vendor-dependent. The protocol stack shown to the right is from the Yahoo Messenger suite.

Within the IM messages, an entire language has sprung up that is designed to shorten the number of characters needed to convey a message. A similar type of shorthand emerged in the early telegraph network as well. This shorthand, which is also now commonly used in chat rooms, email, blogs and other communication vehicles, contains such familiar codes as:

  • AFAIK: As far as I know
  • AFK: Away from keyboard
  • BBL: Be back later
  • BRB: Be right back
  • CYA: See you
  • FWIW: For what it's worth
  • LOL: laughing out loud
  • OIC: Oh, I see!
  • OMG: Oh my god!
  • ROFL: rolling on the floor laughing
  • WTG: Way to go!

IM Applications

In addition to IM system readily available on the Internet, IM is also available in many groupware packages used by businesses internally. This includes Lotus Notes, Microsoft Exchange and Novell Groupwise, to name a few. Many businesses find that IM facilities communication in a way not as disruptive as email or the telephone. Using the system, the status of a user can be quickly determined. A user that is sitting at their computer is arguably less disrupted by a computer-based short exchange than by having to shift their attention to a completely different device (i.e., the telephone).


<mp3></mp3> | Instant messaging (IM)