Instant Messaging

IM consists of two main features. The first is collaboration through instant messages, whiteboarding, voice communication, or application sharing. Instant messages differ from e-mail in that they pop up on the receiving user 's screen immediately after the message is sent ”there is no delay. They also differ from e-mail in that a user can block another user from sending an instant message. The only way you can "block" people from sending you e-mail is by automatically deleting the message or marking the user as an unsolicited e-mailer.

The second and perhaps the more interesting feature is the ability to track and display "presence" information about specified contacts. For example, a user can track her team ”she can track whether team members are online, away from their computers, and so on. A user can also track the availability and status of virtual teams across the Internet. This is where the real power of presence technology lies.

As I mentioned, IM is now included with the new Live Communications Server from Microsoft. This server relies on Windows Server 2003 for its core components . The Live Communications Server IM infrastructure uses Active Directory and allows the user to extend the services she can offer and develop in the Microsoft environment. Furthermore, the Windows Messenger Service client can be installed on workstations so users in an organization can leverage IM technology.

You might wonder how MSN Messenger and Windows Messenger differ. Windows Messenger is a superset of MSN Messenger and supports technologies such as Live Communications Server and the older Exchange Server IM server. MSN Messenger supports only the .NET Messenger Service, which is hosted by Microsoft. For corporate environments, you should use Windows Messenger.

You can take advantage of IM features in your collaborative Exchange applications by integrating IM, presence technology, or both. A number of APIs from Microsoft make the process of integrating IM in your applications easy. In this chapter, we will look at these APIs, which include the Windows Messenger APIs and the Live Communications Client API.

Before we look at the details of these APIs, take a look at the updated main page of the Training application, shown in Figure 19-1, which has IM functionality added. In the sample, students can see which instructors are on line.

Figure 19-1: The updated Training application main page with IM technology added