[Jmap] Hacker News Discussion - getMailboxes single data set vs tree primitives or paging

[Bron Gondwana <[e-mail]>]

https://news.ycombinator.com/item?id=14284526

It's a rather silly discussion that went off onto a tangent, that's HN for you.  The key interesting point is this:

A quick look at the protocol looks like in order to get a list of mailboxes, you have to ask for them all. In IMAP, you can say, show me top level mailboxes, show me direct child mailboxes of mailbox x, etc. In a previous role, I was responsible for working on a mail archiving solution which had a large hierarchy of folders (into the thousands IIRC) in a single account. Access to the archive was via IMAP. Looks to me that JMAP here would require the client to potentially fetch megabytes of data just to start showing a list of folders, where the solution we had with IMAP probably took a couple of kilobytes at most to get started.

...

and the followup:

> Of course nothing stops you storing thousands of mailboxes in a non-heirarchical layout and making IMAP have large LIST fetches too.

Yes. I would issue the LIST command, and as the IMAP server started streaming the results to the client, I would immediately process each mailbox as soon as it was down, rather than waiting for them all to be retrieved. I fear that with a JSON based protocol, most server and client implementations wouldn't deal with streaming (although they technically could), and would just deal with completed blobs.

...

I think it is worth discussing the tradeoffs in terms of additional complexity to offer paging, tree filtering (parentIds: [...]) or both in the standard.  The pro side, you can access potentially millions of mailboxes without needing to know all the folder ids up front.  On the con side, it's more complexity for the server (client can always just fetch everything anyway if it doesn't care) - and most clients seem to fetch the entire tree anyway, so it just means more round trips for them.

Bron.

-- 
  Bron Gondwana
  [e-mail]