Specify behavior when multiple controlling pages are connected to the session

[markafoltz]

An implication of reconnection is that multiple pages may connect to the same presentation. The behavior of the API should be defined for this scenario. Specifically,

• Firing of onstatechange = "connected"/"disconnected" on both sides
• Semantics of close() on both sides

[anssiko]

Noted as an issue in the "Usage on Remote Screen" section in the spec: http://w3c.github.io/presentation-api/#usage-on-remote-screen

[markafoltz]

Adding to this issue from #36 discussion of how messaging should be done between the presentation and multiple connected sessions.

In some scenarios the presented page may have active connections to multiple PresentationSessions on other pages. In a gaming scenario, each connected session would represent a game player. Some information (like dealing a card into the hand) should be sent to one player, while other information (playing a card face up) should be sent to all players.

We need to specify:

1. How the presented page may communicate to a specific connected page
2. How the presented page may broadcast - communicate to all specific connected pages

Note this thread discussing some concrete spec changes to facilitate this case.

[jakearchibald]

The SharedWorker model of a connect event that provides access to the connecting client may help here.

[anssiko]

Agreed with @jakearchibald on that. Would you @mfoltzgoogle with help from @drott like to investigate this further?

[tidoust]

PROPOSED RESOLUTION: starting point for #19 is Promise NP.getSession(), PresentationSession[] NP.getSessions(), NP.onsessionavailable event when set of sessions changes (with possible naming changes)

See related discussion at F2F in Berlin:
http://www.w3.org/2015/05/19-webscreens-minutes.html#item12

[anssiko]

ACTION: @mfoltzgoogle to look at renaming "sessions" for controlling and presenting sides. [recorded in http://www.w3.org/2015/05/19-webscreens-minutes.html#action12]

ACTION: @mfoltzgoogle to fix spec to refer to updated Presentation idiom [recorded in http://www.w3.org/2015/05/19-webscreens-minutes.html#action13]