I like to solve application problems using the Web (statelessness, hypermedia, self-descriptive representations, and uniform interfaces) to produce an asymptotically tight bound solution!

Friday, November 06, 2009

Use Cases for DataCache

I discussed a set of use cases not well supported by HTML5 ApplicationCache with the HTML WG during a breakout session at TPAC. These use cases were the basis for AtomDB are being solved by the DataCache API.

Found out that OMA and AT&T had similar ideas too. Also learnt that these techniques could be merged with HTTP caching.

Hixie agreed these use cases covered the ones the GMail team had asked for but he favored waiting until after AppCache had stabilized and browser implemented other HTML5 stuff.


Parashuram said...

IMHO, the data URLs that would have to be cached would usually be requested using AJAX. Hence, this functionality can be achieved with a combination of AppCache and WebDatabase specifications.
Since we really dont care about what type of data the server returns, I am not sure if there is a case of interoperability here.

Nikunj Mehta said...


How would you show a thumbnail of an image that you may have downloaded as the attachment for an email? That would require you to use an <img> tag. Not everything can be put through Ajax requests.

Parashuram said...

Dynamic thumbnails today are usually downloaded a image sprites to save the number of HTTP connections made to the server.
In our given context, to show (and cache)dynamic image data, AJAX requests are made, with responses returning data URIs of the images. The returned result can be stored and displayed with AJAX.

For really large images (and for IE that does not support data URIs), the base64 image data can be sent and drawn on canvas with Javascript. Improvements like JPEG decoders written in Javascript are also an option when encoding is required.

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I have been an avid student of the evolution of the Web and its application to business problems.

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