[Standards] Re: Inband Images

Richard Dobson richard at dobson-i.net
Wed Mar 28 21:29:38 UTC 2007

> Larger images would use an approach similar to the one used in HTML 
> mails, the message packet would also include a  hash to avoid doing the 
> same file transfer multiple times.

> Keep in mind that file transfers take 1-2sec to set up best case, so it 
> should be avoided at all cost.

MSN seems to manage ok, the way MSN works is that it uses a method 
similar to the cid method documented on the wiki, where it just 
transmits the file hash of the image, and if the receiver does not 
already have the image it uses an IBB file transfer mechanism to 
download it from the sender, this has the massive benefit of only 
transferring the image data if the receiver does not already have it, 
potentially saving a lot of bandwidth that would otherwise be wasted if 
the image data was transferred even if the receiver already had it (as 
the data: method would work).


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