1.3.2 Channels

A channel is a subdivision of a connection through which the server can send messages targeting composition engine resources. The messages can be grouped in batches. This allows clients to be built in a way that prevents visual artifacts, such as flashing and tearing in a predictable manner.

For each channel used to send messages from the server to the client, there is a corresponding back-channel used to send messages from the client back to the server. The server receives only a small set of messages from the client. These messages fall into three categories: response messages, informational notifications, and critical notifications.