A spatial event map system including server-side data processor that maintains a spatial event map which locates events in a workspace. The spatial event map includes a log of events, entries in the log having a location of a graphical target of the event in the workspace and a time. The system includes logic to send messages including an event, a location of a graphical target of the event in the workspace and a time, to client-side network nodes; and to receive messages identifying events that create or modify a graphical target, and to add corresponding entries to the log of events. The events can include history events that are sent to the other client-side network nodes, and added to the log for the corresponding history events, and ephemeral events that are sent to other client-side network nodes without adding corresponding entries in the log.