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instant messaging
Instant messaging, or IM, is a popular and now ubiquitous medium for sending messages to other persons on the Internet.
Instant messaging is a technology through which a person can send short text messages to others on the same computer or over a computer network. The recipients receive the message instantly and can send a reply right away or at a more convenient time. IM is therefore a powerful middle ground between email and real-time chat systems.
With most IM networks, users connect to a centralized IM server with an instant-messaging client. They sign in with a login id and a password, and the network sends the online status of everyone on the user's contact list and alerts others of the user's online status. Once connected, the user may send messages to others on the same IM network via the centralized server.
There are several major IM networks in use today:
- Jabber - Decentralized, open protocol, 21 million users at least.
- AOL Instant Messenger (AIM) - 54 million active users, 195 total.
- Google Talk - Jabber based.
- ICQ - 20 million active users, 200 total.
- MSN Messenger - 29 million active users, 155 total.
- Yahoo! Messenger - 20 million active users.
(the userbase is estimated for the 2003-2006 period [1]).
Most IM networks are incompatible with others. Although AIM and ICQ users can see each others' status and send messages to each other, interoperability is otherwise nonexistent. Proprietary networks have a vested interest in keeping their networks closed. This led to the rise of multi-network clients, such as Gaim and Trillian. These clients allow users to connect to more than one IM network at once instead of running each official client separately. A user must still register with and sign in to each individual IM network, but can message his friends on various networks using a common interface, which may or may not have more features (such as spell checking) than the official clients.
Many IM clients and networks also presently include more advanced functions, like graphical emoticons integrated in the text, offline messages that are held by the server until the recipient signs in, file transfers, and video and voice chat.
Security[edit]
Most IM networks use chat servers to store contact lists and relay IMs, which are sent in plain text. This means that the owners of the IM networks know who is talking to whom, and what is said. Certain networks (such as AIM) allow a user to directly connect to another user, bypassing the central servers, but this reveals the users' IP addresses to one another. Some third-party clients offer client-to-client encryption, meaning the server owners will no longer be able to read the messages exchanged. Users should still consider that their IM clients can theoretically be compromised, for example by a virus, into revealing the user's IP address and other sensitive data. All the usual precautions regarding safety and anonymity (running an up-to-date system, antivirus and so on) should be considered.
Decentralized instant messaging[edit]
Peer-to-peer technology can be used to build decentralized instant messaging systems. In these systems a distributed hash table lookup can be used to determine if buddies are online or not. This instant messaging is effective because it works without a setup of a central server and its failure risk. The risks of central surveillance or censorship over the messaging network are also reduced.
Decentralized instant messaging software:
- CSpace - also provides file sharing functionality.
- Retroshare - strictly friend-to-friend system (you only communicate with your friends, not with random people on the network). Group chat is supported. Provides filesharing.
- WASTE - a relatively popular system, but used to suffer scalability problems in the protocol. Linux support appears to be deficient. Provides filesharing.
- directnet - Group chat with channels is supported. Alpha software (on-going development), as of June 2007.
External links[edit]
Official IM clients:
Third-party clients:
- Gaim - an Open Source IM client for Windows, Mac OS X, Linux, and BSD which supports the above IM networks plus others.
- Trillian - a Windows IM client that supports AIM, Yahoo!, ICQ, MSN and IRC.
| This article contains content from Wikipedia. Current versions of the GNU FDL article instant messaging on WP may contain information useful to the improvement of this article | WP |
