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I am trying to build a web app for iphone, and I don't understand

  • how to cache all the files under the "images" directory ?

  • and I modify one file on the server like "brandDB.txt", how to make the cache manifest update this file, and this file only to avoid downloading everything again ?

Thanks

CACHE MANIFEST
# 20131104-1430
index.html
brandDB.txt
icon.png
splashiphone.png
touch-icon-iphone.png
css/style.css
images/shareicon.png
images/bourez.png
images/john.png
...

NETWORK:
*

FALLBACK:
Louis
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3 Answers3

2

I did a program to easily generate the cache manifest file with the complete list directly from the Windows explorer, if you need it : http://matthieu.com/cmfg/

Matthieu Chavigny
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1

how to cache all the files under the "images" directory ?

List them all in the manifest file (easiest to use a script to generate the list if it's a lot of files).

how to make the cache manifest update this file, and this file only to avoid downloading everything again

  1. Ensure your HTTP headers are set correctly for the frequency of updates you expect
  2. Update the manifest file

The browser will populate the app cache from its own cache if you've set the headers on each file to allow caching. If you want to version control the files without using HTTP headers, add a query string to the end of the file, eg. brandDB.txt?v=1 - be sure to update the reference in the application if you do that, however.

robertc
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  • Thanks... I am gonna use a command line to generate the cache manifest : `echo "CACHE MANIFEST" > cache.manifest; find . -type f | sed "s#^\./##" | grep -vi "ds_store" | grep -vi "~" >> cache.manifest; printf "\nNETWORK:\n*\n\nFALLBACK:\n\n" >> cache.manifest && cat cache.manifest` – Louis Nov 04 '13 at 14:34
  • I am not sure I understand your answer to question #2, I only have one html file and the other files are js, images, css, etc. – Louis Nov 04 '13 at 14:43
  • @Louis Which bit do you not understand? – robertc Nov 04 '13 at 14:48
  • the first point : by http headers I guess you mean this type of thing ``, but I don't want to refresh `brandDB.txt` at a given frequency, I want to refresh it when there has been a change to it on the server (by me). 2. I understand if I modify the manifest file, the client will see it and reload the files, but I would like to reload only the modified files not all files. 3. "set the headers on each file to allow caching." I only have one html file : `index.html` the rest is images, css, js, etc. – Louis Nov 05 '13 at 11:16
  • @Louis 1. No, I mean headers on [HTTP](http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol) requests, `meta http-equiv` is basically meaningless for anything but files on your local disk drive; I know you don't want to refresh at a given frequency, but a browser will re-request after an amount of time determined by HTTP headers. 2. Then you're going to have to [set your headers carefully](https://developers.google.com/speed/docs/best-practices/caching), or use versioning as I described above; 3. They are all files, all are served with HTTP headers – robertc Nov 05 '13 at 11:42
  • thanks Robert, I have never used these. I don't understand where should I "set" the Http headers...it says here I can use meta http-equiv http://stackoverflow.com/questions/4480304/how-to-set-http-headers-for-cache-control . Moreover I thought the idea of a manifest file was to manage these sort of thing....for me it's easier to update the manifest file when I want to update the file if possible. If I understand correctly updating the manifest file will make the client redownload every files. – Louis Nov 06 '13 at 20:30
  • @Louis Please unaccept my answer, I don't really have the time to write you a tutorial on how caching works in comments – robertc Nov 07 '13 at 10:38
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Well, What I'm going to say, unfortunately is as Jake Archibald Said: "Application cache is a douchebag !" (Good Article on how it works (not actually a douchebag))

http://alistapart.com/article/application-cache-is-a-douchebag

Basically, you could create a script to list all your files in your image directory and paste it inside a generated AppCache File.

Application cache will only update when its file's content is changed , you'll also need ensure that the file itself is not cached.

I think you'll be needing your clients to reload the page twice for them to actually see the updates. (You could however using javascript tell the user that the page has updated and they'll need to refresh)

Abdoul Sy
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