Re: Draft of Second Screen Presentation Working Group Charter available (was: Heads-Up: Plan for Working Group on Second Screen Presentation)

Hi MarkF, All,

On 08 May 2014, at 02:53, mark a. foltz <mfoltz@google.com> wrote:

> Hi Anssi,
> 
> Thank you for drafting the Webscreens WG charter.  I have spoken with colleagues at Google and we have the following feedback:

Thanks for your review and feedback.

> (1) The scope of the charter does not specifically mention the following scenarios:  one page controlling the content on multiple displays, or multiple pages controlling content on a remote display (possibly across multiple user agents).  We also want to ensure that the presentation can be controlled across page navigations in the same UA given some scope (e.g., origin scope).  We feel these are necessary to have a usable and complete specification.

I feel this needs to be clarified too to make multiple primary devices, multiple secondary screens, interactions and relationships between them clear.

To break this down a bit I’m hearing good use cases for the following exists:

(1) one-to-one

This is the basic case that should be clear in the Charter, e.g. a single external display connected to a laptop.

(2) one-to-many 

E.g. multiple displays connected to a laptop.

(3) many-to-one

A remote device that is capable of rendering a page is being controlled with multiple primary devices. This leaves out display connections that support video only e.g. HDMI etc.

We should clarify what makes a reasonable scope that allows the group to produce a spec that can be implemented widely, supports a wide spectrum of different display devices while allowing more advanced use cases for devices that are able to render the page remotely.

Dong-Young suggested in his review [1] to add "multiple UA case to the second bullet of 2.4” [that is the Out of Scope section.] I feel we should not be this strict.

MarkF - feel free to work out some text for this section. I’m happy to help refine it.

> (2) In the two-UA case, the charter hints that the software controlling the remote screen is capable of displaying arbitrary Web content.  However, this is not always the case; there are a large number of devices (e.g., smart TVs, digital picture frames, set-top boxes) that can display a fixed set of "apps" or Web media types.  As there are millions of these devices deployed, we feel the charter should be written so as not leave these out.

I’m hearing we should clarify what is the definition of the User Agent, and make it clear that the primary device in the charter is an User Agent. Some specifications talk explicitly about an HTML User Agent to refer to web browsers explicitly. In the proposed charter we use the User Agent term, for which the established definitions reads as follows:

[[

A user agent is any software that retrieves, renders and facilitates end-user interaction with web content. User agents include web browsers, media players, plug-ins, extension and web applications that help in retrieving, rendering and interacting with web content.

http://www.w3.org/TR/UAAG20/#introduction

]]

Would the inclusion of this definition, and a clarification that the primary device is a User Agent, address your concern?

> (3) We want to ensure that the language does not restrict the method of screen discovery or control, which could be a variety of implementations, including the use of cloud services or the use of application specific screen discovery mechanisms.

This would mean we’d move the bullets from "2.2 Phase 2” to the “2.4 Out of Scope” section.

All - any objections for that? As Wayne noted [2], we can experiment with these aspects in the Second Screen Presentation Community Group and/or in other groups as per “4.3 External Groups”.

> (4) The phase 2 scope - the definition of open network protocols for discovery, control, media streaming - is really an *implementation* specification and would be better handled in a different forum such as the IETF.  Although the parties in the WG would likely have a direct interest, separating the two processes would result in a W3C spec that is focused on the API and requirements, and a network protocol suite that could interoperate across software platforms (including native desktop and mobile apps).  There are prior models for a similar spec process such as WebRTC and Push API.

Indeed, the work on spec suites that include an API and an associated protocol have been split across multiple forums so far. I think the first work item that took this approach was WebSockets: its API was defined in the W3C while the WebSocket protocol was defined by the IETF.

I included the Phase 2 to the Charter given some CG participants expressed interest to work on that. It looks like that work should happen outside the proposed Working Group, e.g. in the Community Group for the API(s), and in the IETF for the protocol(s).

> I plan to send a pull request with a set of suggested edits based on the above (after hearing any feedback you might have).

Thank you for help! A PR would be much appreciated.

Thanks,

-Anssi

[1] http://lists.w3.org/Archives/Public/public-webscreens/2014May/0005.html
[2] http://lists.w3.org/Archives/Public/public-webscreens/2014May/0004.html

Received on Thursday, 8 May 2014 07:52:59 UTC