On 27/05/2012 12:36, SULLIVAN, BRYAN L wrote:
Re "At install time or when I am browsing apps, how does a server know my screen 
resolution? Or is this restriction imposed on by the user agent?": When browsing 
apps, the server can easily access the screen and window DOM attributes.
Right, but that requires some communication that is implicit in the spec. I'm trying to figure out what data is leaving my device and going to the server, and why (i.e., what is the expected life cycle model). There is all sorts of things that are implied going on behind the scenes that this spec eludes to (e.g., installation management/sync across devices), and it's good to get a sense of how it all comes together. If it's not clear in the spec, then I have a hard time seeing how multiple user agents will be able behave in an interoperable manner.
  When installing apps, the installer (browser, app manager, etc) can provide a 
warning to the user that the app is designed for use on larger screens, and may 
not work properly on this device.
Sure, but doesn't that lead to the original complaint that certain developers don't want their application to install at all for PR reasons?

Ps: Bryan, can I kindly ask that you please stop top-posting on W3C mailing lists. It makes it hard to keep threads together. Please see:
http://wiki.whatwg.org/wiki/FAQ#Should_I_top-post_or_reply_inline.3F

Thanks,
Bryan Sullivan

-----Original Message-----
From: Marcos Caceres [mailto:w...@marcosc.com]
Sent: Sunday, May 27, 2012 1:35 AM
To: Anant Narayanan
Cc: SULLIVAN, BRYAN L; public-webapps@w3.org
Subject: Re: [manifest] screen sizes, Re: Review of Web Application Manifest 
Format and Management APIs



On 26 May 2012, at 18:32, Anant Narayanan <an...@mozilla.com> wrote:

On 05/25/2012 09:25 AM, Marcos Caceres wrote:

On Friday, May 25, 2012 at 4:34 PM, SULLIVAN, BRYAN L wrote:

Marcos,

Re "I thought we had stopped the whole designing for particular screen sizes, etc. a 
long time ago.", that may be the still-closely-held goal, but the reality is that 
designing for multiple screen sizes (and pixel densities) is still far from simple. Even 
with all the tools that have been developed in CSS and Media Queries.

So if developers want to claim that they have focused their design on specific 
form factors (and presumably tested it thoroughly on them), this seems like a 
good thing as it allows them to be more certain that their apps won't be 
distributed to users of devices on which they won't work well (which will 
negatively impact the developer's reputation, use of the app, appstore etc), or 
if distributed to such users, will be clearly identified as not being designed 
for those devices.

Like many of the things we wanted to do in widget manifest structures in BONDI 
and WAC, if these get pulled from the plan the only fallback is developer 
ecosystem-specific app metadata, which in the end evaporates with the developer 
ecosystems, or never achieves widespread use or interoperability. So the 
problem is not solved for developers by leaving these things out of standards, 
where there is a strong use case.

Still sounds to me like "Made for<insert everyone's favorite 90's browser here>, and 
best viewed at 800x600" … and look how well that turned out. Even if we don't focus on 
mobile devices, it seems like a silly requirement as I can just adjust my browser window to 
whatever size I want (there is no reason to believe I won't be able to do that on future mobile 
devices). I.e., screen size and application display area are not the same thing and this 
metadata attribute seems to assume so.
The intent for the screen_size parameters is not to let the developer enforce a 
particular screen size or resolution, but rather specify the *minimum* width 
and height required by the app. This means that on a screen below the specified 
size, the app will not function at all.
To make this more clear, maybe call this min_screen_size.

I will also note that it is upto the app store to interpret this field however 
they'd like. If they do not want to disallow installs on devices that don't 
meet the developer-specified criteria, that's fine. However, we should still 
convey this information from the developer to the store via the manifest.
At install time or when I am browsing apps, how does a server know my screen 
resolution? Or is this restriction imposed on by the user agent?

It is unrealistic to assume that all app developers will make a responsive 
design for all possible screen sizes. The tools aren't great and it costs time 
and money. We added this field after we received a request from the developer 
of a popular game that only worked on desktops, but not mobile phones (due to 
size). They wanted to make sure users weren't able to install them in places 
the app wasn't designed for and get a bad impression of the company. I think 
this is really important.
I think that's fine, but as Scott pointed pointed out, user agents have a 
history of allowing users to bypass these kinds of restrictions (or users hack 
around them). I think this field can only really serve as a warning that the 
app might not work as expected.




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