Multipoint publishing allows clients to publish to servers with only one client-to-server connection. This feature enables you to build large-scale live broadcasting applications, even with servers or subscribers in different geographic locations.

The application flow that corresponds to this illustration works like this:

1. A client connects to an application on Server 1 in New York City and starts publishing a live stream.
2. The application on Server 1 receives an application.onPublish event, which it handles in its main.asc file.
3. The application creates two NetStream objects in its onPublish event handler to stream to Server 2 (Chicago) and Server 3 (Los Angeles).
4. Server 1 rebroadcasts the live stream to Server 2 and Server 3 with a NetStream.publish() method.
5. Subscribers connecting to Server 2 and Server 3 receive the same live stream.
6. The application receives an application.onUnpublish event when the client stops publishing.

To use multipoint publishing, you need to write server-side code in a main.asc file.