RE: Media Queries and optimizing what data gets transferred

> With that said, I don't think a "Media Queries vs. Client hints" debate is productive. 

I think standards should not be adopted without at least a technical discussion and input from all stake holders.


> IMO both client-side & server-side solutions have a place, each with its slightly different use-cases and slightly different trade-offs.

Could you please elaborate on why you think the client-hints proposal in particular has a place?

There appear to be two distinct proposals:

1. Client-side adaptation: the server informs the client of the available resources and the client uses the client-side state to make a choice.  Pros: the user can choose the selection algorithm; browser vendors can innovate; the user can keep their state secure at the UA; the server does not have to deal with data collection issues; only a small set of distinct available resources need to be keyed in the cache; new resources only need to be download when one of these distinct choices changes; the UA can reuse a resource already available (such as resizing an image on hand); no changes are required on the server or the CDN; developer tools can help insert and optimized images and resource options into the HTML and then the content can be delivered statically or with less server/CDN complexity.

2. Client-hints based server-side adaptation: the client sends the server a range of client-side state and the server uses a secret algorithm to make a choice. Cons: The input parameter space is large and each combination requires a separate cache key which is more demanding on the cache; any change to the input parameters requires a re-validation request to confirm if a resource choice has changed; the client is not able to make informed decisions to reuse resources on hand if the client-side state changes (for example it can not resize an image on hand); users are required to share potentially private state which creates data collection problems for the server; users who choose not to share their private state are excluded; requires adoption of the client-hints standard; requires sending the resource choices to the client anyway to handle UAs that do not implement or have disabled the client-hints header and this leads to yet more cache duplication.

It is clear that client-side adaptation solves all the technical problems that client-hints based server-side adaptation offers and that client-side adaptation offers no advantages and significant disadvantages.  The proponents have failed to address the issues and some replies are rather arrogant and insulting which leads me to believe they have no answers.

cheers
Fred