Overview#Instant Messaging (IM) is a type of online chat that offers real-time text transmission over the Internet.
A LAN messenger operates in a similar way over a local area network. Short messages are typically transmitted between two parties, when each user chooses to complete a thought and select "send".
Some Instant Messaging applications can use push technology to provide real-time text, which transmits messages character by character, as they are composed.
Instant Messaging applications communicate with multiple participants at the same time via group chats where Short Message Service can not.
Instant Messaging includes:
Instant Messaging Standards#There have been several attempts to create a unified standard for Instant Messaging:
- IETF's Session Initiation Protocol (SIP) and SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE),
- Application Exchange (APEX)
- Instant Messaging and Presence Protocol (IMPP),
- the open XML-based Extensible Messaging and Presence Protocol (XMPP)
- Open Mobile Alliance's Instant Messaging and Presence Service developed specifically for Mobile Devices.
Most attempts at producing a unified standard for the major IM providers (AOL, Yahoo! and Microsoft) have failed, and each continues to use its own proprietary protocol.
However, while discussions at IETF were stalled, Reuters signed the first inter-service provider connectivity agreement in September 2003. This agreement enabled AIM, ICQ and MSN Messenger users to talk with Reuters Messaging counterparts and vice versa. Following this, Microsoft, Yahoo! and AOL agreed to a deal in which Microsoft's Live Communications Server 2005 users would also have the possibility to talk to public instant messaging users. This deal established SIP/SIMPLE as a standard for protocol interoperability and established a connectivity fee for accessing public instant messaging groups or services.
Separately, on October 13, 2005, Microsoft and Yahoo! announced that by the 3rd quarter of 2006 they would interoperate using SIP/SIMPLE, which was followed, in December 2005, by the AOL and Google strategic partnership deal in which Google Talk users would be able to communicate with AIM and ICQ users provided they have an AIM account.
There are two ways to combine the many disparate protocols:
- Combine the many disparate protocols inside the IM client application.
- Combine the many disparate protocols inside the IM server application. This approach moves the task of communicating with the other services to the server. Clients need not know or care about other IM protocols. For example, LCS 2005 Public IM Connectivity. This approach is popular in XMPP servers; however, the so-called transport projects suffer the same reverse engineering difficulties as any other project involved with closed protocols or formats.
Some approaches allow organizations to deploy their own, private Instant Messaging network by enabling them to restrict access to the server (often with the IM network entirely behind their firewall) and administer user permissions. Other corporate messaging systems allow registered users to also connect from outside the corporation LAN, by using an encrypted, firewall-friendly, HTTPS-based protocol. Usually, a dedicated corporate IM server has several advantages, such as pre-populated contact lists, integrated authentication, and better security and privacy.
Certain networks have made changes to prevent them from being used by such multi-network IM clients. For example, Trillian had to release several revisions and patches to allow its users to access the MSN, AOL, and Yahoo! networks, after changes were made to these networks. The major IM providers usually cite the need for formal agreements, and security concerns as reasons for making these changes.
The use of proprietary protocols has meant that many Instant Messaging networks have been incompatible and users have been unable to reach users on other networks. This may have allowed social networking with IM-like features and text messaging an opportunity to gain market share at the expense of IM.