A user who opens Windows Media Player or Windows Media Center (from the PC or from an Extender for Windows Media Center) can browse, interact with, and play content from any device that implements the DMS role in the home network. A DMS is a DLNA-defined networked device role. A DMS exposes content to the network and, when content is requested, it transfers that content to the requesting device. Exposing and transferring content are the two fundamental functions that this device performs. A DMS exposes content to the network by using a UPnP service called a content directory service. The content directory service defines a protocol to query the DMS database and to describe the media in the database. A DMS transfers content to the network by using the HTTP protocol with extensions to support trick modes such as fast forward and fast rewind, transfer modes such as stream or download, and so on.
In Windows 7, discovery of media servers on the network is automatic and requires no configuration. In Windows Media Player, media servers are known as Other Libraries and are prominently displayed in the navigation pane. Figure 2 shows the automatic discovery of a digital media server named Karen (desktop) under Other Libraries in the navigation pane of Windows Media Player.