[tech] Questions about cache

[Luke Emmet]

On 22-Dec-2020 22:40, Stephen wrote:
>
> Is there some guarantee that a capsule writer has on what may _not_ be 
> cached, or is it entirely up to the client's discretion? If the 
> latter, is this something which could be clarified in the spec? My 
> impression from this ML was that caching is frowned upon (except for 
> perhaps navigating back and forth through your history), but this has 
> not been my experience (at least with amfora).

As a user facing client author, the semantics that makes most sense to 
me, whilst recognising the Gemini does not have any mechanism to 
indicate staleness is as follows:

1. Any overt action by the user to activate or refresh a link retrieves 
a fresh copy

2. Navigation backwards and forwards through history may use a local 
cached version

This is largely the equivalent of web pages having expires=0

Other clients (like crawlers, indexers and the like) preserve their own 
copies on the understanding that the data will be out of date - but 
still their cache may be useful for their own purposes.

I think a client caching a resource when the user has overtly requested 
it is probably overstepping its authority to provide what the user 
expected/intended.

  - Luke