INSTANT MESSAGING

July 25, 2006

Prepared by

Michael Hunter, IT Technical Writer

WHAT IS INSTANT MESSAGING?

     Instant messaging (IM) is real-time communication between two users via computers. To be more succinct, IM is a type of communications service that enables users to create a kind of virtual private chat room with another individual to communicate in real time over the Internet. Typically, the instant messaging system alerts the user whenever someone on their private list is online. The user can then initiate a chat session with that particular individual.

     There are two types of instant messaging services available: consumer instant messaging services and enterprise instant messaging services. Examples of consumer IM services are AOL’s AIM and Microsoft’s MSN Messenger. These services do not offer security, monitoring, or logging of connections and can create problems for corporate networks. Enterprise instant messaging services are standalone instant messaging systems designed with security features to provide secure IM capabilities to businesses.

 HOW DOES INSTANT MESSAGING WORK?

     The following description varies from service to service but the basic steps described below apply to most consumer instant messaging services.

     When a user downloads the software on his or her computer, they are installing an application client that connects with the service’s server whenever they are online and the client is running. A client is an application that resides on a computer and relies on information provided by a server to perform its operations. A server is a computer on a network that manages resources used by its clients, e.g., a network server manages network traffic.

     When a user downloads the application software for an instant messaging service, a copy of the software client is installed onto the computer. When the user opens the client, a connection is made with the server using a proprietary communication protocol. Once the connection is made, the user can log on using a logon name and password that is stored in the server’s database. If the logon and password are correct the client will send the server the IP address and port of the computer the client is using. An IP address is the addressing system used by most networks to identify your computer on the network. A port is an endpoint to a logical connection in a network, e.g., port 80 is HTTP traffic.

     When the client has connected to the server and provided the IP address and port number, the server will send the client the user’s buddy list and the activity status of each person on that list. A buddy list is a list of the user’s friends, family, or co-workers that are using the same IM service. If a person on the buddy list is online and active, the server will notify the user of that person’s status and send the IP address and port number of that person to the user’s client. To communicate with a person on the buddy list, the user simply opens a chat room and initiates a conversation. At this point the messages are sent and received between the computers and bypasses the server. When the conversation is finished, the user closes the window and exits the client or goes offline, the client sends a terminate session message to the server. The server then notifies the client’s on the buddy list that the user if offline. The server then deletes the temporary file that contained the client’s connection information.

 

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