What happens when you upload a binary to Apple's iTunesConnect?

EDIT: ...and I'm asking because: it might point to thi开发者_如何转开发ngs we can do to speed-up the process.

About a year ago, this process went from being "slow because Apple's servers were under-powered" to being "very slow because Apple used 3 times the bandwidth required to send the binary".

e.g. I submitted a 90Mb app recently, and Xcode4 uploaded over 350Mb of data to Apple.

e.g. just now I submitted an 8Mb binary, and Xcode4 uploaded over 40Mb of data to Apple.

There have been big improvements in the uploader recently (e.g. during one of those uploads above, I lost DSL connection partway. It took Apple about 30 seconds to recover and resume the upload - but previous versions would just crash in that scenario).

But I'm wondering: what is Apple actually doing during upload? The process runs on our local machines - has anyone tried peeking at the net traffic? or at the processes?

I saw a couple of different phases, just by monitoriing 'ps':

1. unzip (for re-doing the code signing)
2. codesign (ditto)
3. Java (for the uploader interface, I believe)
4. then ascp (Apple SCP, I'm guessing?)

Speculation: it uses the same WebDAV implementation as Finder, which is very slow.