即时通讯系统Instant Messaging System

即时通讯系统Instant Messaging System

Instant Messaging (IM) is a form of real-time communication between two or more people based on typed text. The text is conveyed via computers connected over a network such as the Internet.

Overview
Instant messaging (IM) and chat are technologies that create the possibility of real-time text-based communication between two or more participants over the internet or some form of internal network/ intranet. It is important to understand that what separates chat and instant messaging from technologies such as e-mail is the perceived synchronicity of the communication by the user - Chat happens in real-time before your eyes. Some systems allow the sending of messages to people not currently logged on (offline messages), thus removing much of the difference between Instant Messaging and e-mail.

While many IM services have additional features such as: the immediate receipt of acknowledgment or reply, group chatting, conference services (including voice and video), conversation logging and file transfer, those functions are beyond the scope of this article.

IM allows effective and efficient communication, featuring immediate receipt of acknowledgment or reply. In certain cases Instant Messaging involves additional features, which make it even more popular, i.e. to see the other party, e.g. by using web-cams, or to talk directly for free over the Internet.

It is possible to save a conversation for later reference. Instant messages are typically logged in a local message history which closes the gap to the persistent nature of e-mails and facilitates quick exchange of information like URLs or document snippets (which can be unwieldy when communicated via telephone).

History
Instant messaging actually predates the Internet, first appearing on multi-user operating systems like CTSS and Multics[1] in the mid-1960s. Initially, many of these systems, such as CTSS'.SAVED, were used as notification systems for services like printing, but quickly were used to facilitate communication with other users logged in to the same machine. As networks developed, the protocols spread with the networks. Some of these used a peer-to-peer protocol (eg talk, ntalk and ytalk), while others required peers to connect to a server (see talker and IRC). During the Bulletin board system (BBS) phenomenon that peaked during the 1980s, some systems incorporated chat features which were similar to instant messaging; Freelancin' Roundtable was one prime example.

In the last half of the 1980s and into the early 1990s, the Quantum Link online service for Commodore 64 computers offered user-to-user messages between currently connected customers which they called "On-Line Messages" (or OLM for short). Quantum Link's better known later incarnation, America Online, offers a similar product under the name "AOL Instant Messages" (AIM). While the Quantum Link service ran on a Commodore 64, using only the Commodore's PETSCII text-graphics, the screen was visually divided up into sections and OLMs would appear as a yellow bar saying "Message From:" and the name of the sender along with the message across the top of whatever the user was already doing, and presented a list of options for responding.[2] As such, it could be considered a sort of GUI, albeit much more primitive than the later Unix, Windows and Macintosh based GUI IM programs. OLMs were what Q-Link called "Plus Services" meaning they charged an extra per-minute fee on top of the monthly Q-Link access costs.

Modern, Internet-wide, GUI-based messaging clients, as they are known today, began to take off in the mid 1990s with ICQ (1996) being the first, followed by AOL Instant Messenger (AOL Instant Messenger, 1997). AOL later acquired Mirabilis, the creators of ICQ. A few years later ICQ (by now owned by AOL) was awarded two patents for instant messaging by the U.S. patent office. Meanwhile, other companies developed their own applications (Excite, MSN, Ubique, and Yahoo), each with its own proprietary protocol and client; users therefore had to run multiple client applications if they wished to use more than one of these networks. In 1998 IBM released IBM Lotus Sametime, a product based on technology acquired when IBM bought Haifa-based Ubique and Lexington-based Databeam.

In 2000, an open source application and open standards-based protocol called Jabber was launched. Jabber servers could act as gateways to other IM protocols, reducing the need to run multiple clients. Multi-protocol clients such as Digsby,Pidgin, Trillian, Adium and Miranda can use any of the popular IM protocols by using additional local libraries for each protocol. IBM Lotus Sametime's November 2007 release added IBM Lotus Sametime Gateway support for XMPP.

Recently, many instant messaging services have begun to offer video conferencing features, Voice Over IP (VoIP) and web conferencing services. Web conferencing services integrate both video conferencing and instant messaging capabilities. Some newer instant messaging companies are offering desktop sharing, IP radio, and IPTV to the voice and video features.

The term "instant messenger" is a service mark of Time Warner[3] and may not be used in software not affiliated with AOL in the United States. For this reason, the instant messaging client formerly known as Gaim or gaim announced in April 2007 that they would be renamed "Pidgin"

Cooperation
Standard free instant messaging applications offer functions like file transfer, contact lists, the ability to have simultaneous conversations etc. These may be all the functions that a small business needs but larger organisations will require more sophisticated applications that can work together. The solution to finding applications capable of this is to use enterprise versions of instant messaging applications. These include titles like Jabber, Lotus Sametime, Microsoft Office Communicator, etc., which are often integrated with other enterprise applications such as workflow systems. These enterprise applications, or Enterprise Application Integration (EAI), are built to certain constraints, namely storing data in a common format.

There have been several attempts to create a unified standard for instant messaging: IETF's SIP (Session Initiation Protocol) and SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions), APEX (Application Exchange), Prim (Presence and Instant Messaging Protocol), the open XML-based XMPP (Extensible Messaging and Presence Protocol), more commonly known as Jabber and OMA's (Open Mobile Alliance) IMPS (Instant Messaging and Presence Service) created specifically for mobile devices.

Most attempts at creating 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 head of collaboration services, David Gurle (the founder of Microsoft's Real Time Communication and Collaboration business), signed the first inter-service provider connectivity agreement on September 2003. This agreement enabled AIM, ICQ and MSN Messenger users to talk with Reuters Messaging counterparts and vice-versa against an access fee. Following this, Microsoft, Yahoo! and AOL came to a deal where Microsoft's Live Communication 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 clouds. Separately, on October 13, 2005 Microsoft and Yahoo! announced that by (the Northern Hemisphere) summer of 2006 they would interoperate using SIP/SIMPLE which is followed on December 2005 by the AOL and Google strategic partnership deal where Google Talk users would be able to talk with AIM and ICQ users provided they have an identity at AOL.

There are two ways to combine the many disparate protocols:

One way is to combine the many disparate protocols inside the IM client application.
The other way is to combine the many disparate protocols inside the IM server application. This approach moves the task of communicating to 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 Jabber/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, such as that adopted by the Sonork enterprise IM software or the Jabber/XMPP network or Winpopup LAN Messenger, allow organizations to create their own private instant messaging network by enabling them to limit 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 a secure firewall-friendly HTTPS based protocol. Typically, a dedicated corporate IM server has several advantages such as pre-populated contact lists, integrated authentication, and better security and privacy.

Some networks have made changes to prevent them from being utilized 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 typically cite the need for formal agreements as well as security concerns as reasons for making these changes.

[edit] Mobile Instant Messaging
Mobile Instant Messaging (MIM) is a presence enabled messaging service that aims to transpose the desktop messaging experience to the usage scenario of being on the move. While several of the core ideas of the desktop experience on one hand apply to a connected mobile device, others do not: Users usually only look at their phone's screen — presence status changes might occur under different circumstances as happens at the desktop, and several functional limits exist based on the fact that the vast majority of mobile communication devices are chosen by their users to fit into the palm of their hand. Some of the form factor and mobility related differences need to be taken into account in order to create a really adequate, powerful and yet convenient mobile experience: radio bandwidth, memory size, availability of media formats, keypad based input, screen output, CPU performance and battery power are core issues that desktop device users and even nomadic users with connected network.

[edit] Friend-to-friend networks
Instant Messaging may be done in a Friend-to-friend network, in which each node connects to the friends on the friendslist. This allows for communication with friends of friends and for the building of chatrooms for instant messages with all friends on that network.

Emotions are often expressed in shorthand. For example; lol. But a movement is currently underway to be more accurate with the emotional expression. Real time reactions such as (chortle) (snort) (guffaw) or (eye-roll) are rapidly taking the place of acronyms.[citation needed]

[edit] Business application
Instant messaging has proven to be similar to personal computers, e-mail, and the WWW, in that its adoption for use as a business communications medium was driven primarily by individual employees using consumer software at work, rather than by formal mandate or provisioning by corporate information technology departments. Tens of millions of the consumer IM accounts in use are being used for business purposes by employees of companies and other organizations.

In response to the demand for business-grade IM and the need to ensure security and legal compliance, a new type of instant messaging, called "Enterprise Instant Messaging" ("EIM") was created when Lotus Software launched IBM Lotus Sametime in 1998. Microsoft followed suit shortly thereafter with Microsoft Exchange Instant Messaging, later created a new platform called Microsoft Office Live Communications Server, and released Office Communications Server 2007 in October 2007. Both IBM Lotus and Microsoft have introduced federation between their EIM systems and some of the public IM networks so that employees may use a single interface to both their internal EIM system and their contacts on AOL, MSN, and Yahoo!. Current leading EIM platforms include IBM Lotus Sametime, Microsoft Office Communications Server, and Jabber XCP. In addition, industry-focused EIM platforms such as IMtrader from Pivot Incorporated, Reuters Messaging, and Bloomberg Messaging provide enhanced IM capabilities to financial services companies.

The adoption of IM across corporate networks outside of the control of IT organizations creates risks and liabilities for companies who do not effectively manage and support IM use. Companies implement specialized IM archiving and security products and services like those from Secure Computing, Akonix, SurfControl, and ScanSafe to mitigate these risks and provide safe, secure, productive instant messaging capabilities to their employees.

[edit] Practical Use in Enterprise
The popular embrace of IM technology for sharing information has quickly led to organizations adopting IM solutions for the perceived advantages that can be brought by it. As organizations are becoming more information based (McNurlin & Sprague, 2006, p.499) the need for effective knowledge sharing, team working and collaborative environments amongst employees has become vital, especially within more geographically dispersed teams.

Typically IM conversations tend to have a certain "character", they are often short and only cover one topic. Media-switching and multitasking are common throughout, however IM might also be used between established coworkers and friends for longer, more intermittent conversation. In their report of IM use at the workplace Nardi et al. (2000) identifies the four primary functions of IM which are often cited in other reports, These primary functions are:

Quick Questions and Clarifications
Coordinating and scheduling tasks
Coordinating impromptu social meetings
Keeping in touch with friends and family
IM is perhaps best suited to "Quick Questions and Clarifications" as this is the most often mentioned attribute in other reports. A user can "respond rapidly without the overhead of telephone or FTF interaction. For example, IDC reports, "Users see IM as a medium for quick, semi-permanent ‘flashes’ that beg a near-immediate response" (Isaacs et al., 2002). Nardi's second and third observations are enabled in part due to the "Presence Awareness" feature of IM clients in which the user knows who is "available". This is the most relevant for colleagues who share the same physical space as each other and even paves the way for other mediums to take up the task of communication e.g. F2F or Phone. The implication is that viable communication of any sort can in someway be encouraged through IM's "Presence Awareness" feature. (Issacs et al, 2002) supports this view, "IM in business might not be the main tool for of communication, it could just be the meeting point for another type of media e.g. conference calls.

Nardi's third and fourth observations focus on the social use of IM, which have also been widely publicized in other report. That IM is used for keeping in touch with friends and arranging social events has led some employers to believe that it is used primarily for this purpose. According to (Issacs et al, 2002) a market study found that "'Fear of losing employee productivity’ was the greatest concern of businesses in regards to instant messaging".

The study by (Issacs et al, 2002) goes on to suggest this fear is unfounded as it was found that on average "only 13% of conversations contained personal topics", and "only 6.4% were exclusively personal".

A study published in 2007, in the Journal of Computer Mediated Communication, found that workers who used instant messaging on the job reported less interruption than colleagues who did not.[5] Research showed that instant messaging was often used as a substitute for other, more disruptive forms of communication such as the telephone, e-mail, and face-to-face conversations. They found that the conversations were briefer between co-workers when using instant messaging than with the other forms of communications. Because of its unique setup, instant messaging allows users to control how and when they communicate with their coworkers. This technology gives people the ability to flag their availability or postpone responses to a more convenient time, according to one of the researchers.[6]

[edit] Review of Products
"IM solutions can typically be catagorised into two types: Enterprise Instant Messaging (EIM) and Consumer Instant Messaging (CIM). Enterprise solutions use an internal IM server, however this isn't always feasible, particularly for smaller businesses with limited budgets. The second option, using a (CIM) provides the advantage of being inexpensive to implement and has little need for investing in new hardware or server software. However, in recent years open source IM clients such as Jabber have emerged that provide free EIM grade solutions. (Wikipedia,. 2008)