Active Directory

A hierarchical directory structure used by Microsoft servers to store data about objects available on the network.

Basic instant messaging and presence

Includes the basic functionality exposed by Web Service Provider. This includes functionality such as the ability to start and receive IM conversations from one or more users, set the local users presence status, view a local user’s contact list, and view the presence status of remote users.

Client Access Server

The Client Access server, for example, Exchange 2010 Client Access server, is responsible for accepting connections from multiple clients such as browser-based clients, phones, and mobile devices. The external clients gain access to the internal Exchange Server infrastructure through the Client Access server.

Office Communicator

Office Communicator 2007 R2 is a desktop client application featuring real-time communications options such as IM, voice, and video, packaged within a single user experience.

Outlook Live

Browser-based client application featuring e-mail access to Microsoft Exchange 2010 users.

Service Provider

Implementation that exposes key functionality derived from a specific source. In Web Service Provider, the functionality is basic IM and presence. The source is the Office Communications Server front-end server.