Use case: listing available content

[rektide]

As a developer, it would be useful to be able to read what resources are in my own bundle.

Use case example: I am writing a offline capable Zine webapp. I typically have a directory for each issue, and a number of html files in each directory corresponding to pages in my Zine. There is also a "zine browser" main interface that let's me pick which zine I want to read, or skip to pages, and the main interface knows what I was last reading. To let people share my zine, I create a webpackage of the client software, and a number of zine issues.

Dilemma: how does my main interface know what zines are available in the bundle?

Ideally, as a developer, I could have the main-client reader able to ask- what resources do I already know about? Any zines in a webpackage ought to be able to present themselves to my main client, let it know: hey, there's content here.

This issue gets more pointed if users start collecting multiple webpackages, like if I release a new webpackage with new zines. Before- considering the case of only a single webpackage of main-client+zines- it would perhaps not be pleasant but it could be possible to build an index file into my webpackage that enumerates all the content. However when there are multiple webpackages available, it becomes outright impossible to work with this situation. The main-client will not have a way to figure out what is in other bundles.

An implementation of #107 would resolve this use case. If webpackage content were available via the page's Cache APIs then we could use Cache.keys() to discover the content.

There is a related problem in HTTP/2 PUSH, with not being able to detect content: whatwg/fetch#65. As a page, there's no way to detect resources that HTTP/2 PUSH has sent: once again the developer needs to create an out-of-band mechanism to ever be able to access the resource.

I would like to see listing of at least same-origin content added to the use-cases. I hope this example of a Zine illustrates the need and how this capability would help. Thanks.

[jyasskin]

Probably a duplicate of #107.