Using HTML5 web database to store files for offline access

Question

I am attempting to create a simple web app for iPad which needs to be used in places with no internet connectivity. The app is essential a simple \"slideshow\" but also includes

Answer 1

The database has a limit of 5 mb after which the user is prompted to allow for around 20 more mb. The hard limit is 20-25 mb after which you cannot insert any more records into your localstorage.

Answer 2

Just wanted to share my experience as it might be relevant. We have (tried) to develop an iPad based web app that needs to store 1000's of images and files (such as presentations and word documents)

A mock up on Windows (Safari 4 & 5) can import images encoded as base64 into a Web SQL database (blob field) and displaying them using a db callback to set the source of image tags like src="data:image/jpeg;base64,...base65encimagedata..."

Other files (doc, ppt, pdf) had to be uploaded using the offline cache / manifest. Even though we can get them into a database as base64, there was no way to view them.

Now the problem... Desktop Safari lets you create a large SQL database (I did 1 Gig imported 3000 images.) and has not imposed a known limit on the offline cache.

However on the iPad things are less useful because I cannot create a database more then 50Mb, plus the 5Mb cache limit.

Some alternatives (I have not tried them yet) have been:

1. Try Opera Mini (or other available browsers) on the iPad
2. I know Google Chrome (which uses webkit) has a limit on its SQL database size, but you can 'patch it' ( https://groups.google.com/a/chromium.org/group/chromium-html5/browse_thread/thread/8672b2e0cd69a9f7/ebf17070d32c1168?lnk=gst&q=database+size#ebf17070d32c1168) with some SQL to increase its size. Maybe this can be done on the iPad somehow.