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Here's my scenario:

A web site has an index page and a number of content pages (for the sake of argument these are called page1 through page100) all pointing to the same cache manifest URL.

The index page lists all the content pages and lets the user choose which ones he wants to view offline (For the sake of agrgument let's say he selects page 1, 2, and 3). He then clicks the "download" button which in turn posts back the same index page but this time the cache manifest is dynamically generated and includes the selected pages as explicit so they all get downloaded into the offline cache. He can then go offline and view all the pages, so far so good!

Now let's say before he goes offline he goes into page2 and hits the browser refresh button. This will cause the cache manifest to be re-fetched. At this point the cache manifest has no context so there's no way it can include any explicit entries for page 1 or 3. Hence he now has page2 as a master entry (and possibly explicit as well) but 1 and 3 have been removed from the offline cache.

Can anyone think of a sensible way round this? I've wondered about having a separate cache manifest URL for each page but that just feels wrong.

Andy
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  • hmm I've done some more testing and having a separate cache manifest URL for each page looks like a non-starter. When loading the cache-manifest for the index page, if that refers to page1 then the browser will load page1 but won't load the cache manifest for page1 (presumably because it's only loading a single application cache group) – Andy Feb 07 '13 at 15:51

1 Answers1

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Don't include the manifest attribute on the other pages? Maybe don't even include it on the first page unless the user just submitted it so you know what it must contain?

Store the user's selection in a session variable so you always generate the correct manifest?

grr
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  • I don't think the session variable thing will work because when the user comes back online he might have to log back in. I could store it in the database alongside his user ID but that would cause problems if the same user logs in from different places. The problem with not including the manifest on other pages is if the user refreshes page2 and the new version of page2 includes an image that wasn't in the original version of page2 - that image will be a master entry but not an explicit one. – Andy Feb 14 '13 at 15:26
  • At the moment I'm working on the idea of having the index page redirect to index?guid=xxxxxxx and then store the list of documents in the database indexed by guid. It's complex but I still can't think of a simpler solution that works in this scenario – Andy Feb 14 '13 at 15:28