Understanding ASX Metafiles

An ASX file provides information that Microsoft® Media Player uses, such as the Uniform Resource Locator (URL), to receive either unicast or multicast streams from an intranet or the Internet. You also can use ASX files to deliver the path to a stored media file on a network drive, but this can be accomplished through other means as well, and is not covered here. Both Microsoft® NetShow™ and RealNetworks® RealAudio® metafiles can be opened by Media Player. These files are loaded quickly by the client, and contain information for the following purposes:

• To transfer control from the Hypertext Transfer Protocol (HTTP) browser to the player control, so that streams can be directed to the player. If you do not have Microsoft® Internet Explorer, you cannot define hyperlinks in a Web page using the MMS (Microsoft Media Server) protocol because the MMS protocol is not recognized. You can link to an ASX file on a Web server that then points the client to the NetShow server via the MMS protocol.
• To represent an announcement of information necessary to access a program on a NetShow station.
• To provide references to multiple pieces of content and rules for protocol rollover that the client uses to process them.
• To provide a playlist that defines the order in which pieces of content are streamed to the player.