Google: How do you do it?

So its not a big surprise that an oft-requested feature for Beagle is the ability to index a users Gmail messages (like Google Desktop Search). Today we (the Beagle developers) started to investigate just how this is done. While POP3 (and now IMAP) are available, downloading all of a users mail, indexing it, and then caching the text so we can display it. Now, my initial investigation into GDS for Linux revealed that it was calling home via POP3s and downloading lots of data. I have assumed that it was simply iterating over all messages (via POP3), downloading them, indexing them, and caching the compressed content somewhere in Google’s custom indexes.

Now, I had originally planned on this post being an open plea to any and everyone at Google asking them to open up the Gmail access API, but seeing as its just the plain old ugly POP3 (maybe a cool extension), were stuck biting the bullet and implementing a remote mail access layer.

Anyways, given how incredible Google has been in a million other situations, I thought I would throw out 2 wildly out-of-this-world questions, I wouldn’t expect to get a response, but before I spend the time figuring it all out, I felt like I should at least ask.

• Are there some special POP Extensions available in Gmail? Is there some helper web api? Or does GDS really just have a POP3 crawler?
• Is your compression/text storage library open source? (or documented in some research paper at all?) Beagle has always struggled with how to best handle storing copies of a documents text so that it might be made available in interfaces. While we do have a new hybrid text cache (text over 4k on the filesystem, under in a sqlite db, all compressed) we were still no where near as small as the GDS indexes. A cursory examination reveals that the GDS indexes are some form of b-tree on disk, but how are you compressing all that text so small? Is there some substitution/reconstruction algorithm? (It seems like that would be wildly expensive, but who knows).

Anyways, its a long shot, and its pretty far out there, but for the sake of not passing up answers that I can’t seem to find elsewhere on the net, I have asked.