[haiku-development] Re: [GSoC proposal] IMAP FS - A few queries
- From: "Ingo Weinhold" <ingo_weinhold@xxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Thu, 14 Apr 2011 20:27:42 +0200
On Thu, 14 Apr 2011 10:23:29 -0700 (PDT) Donn Cave <donn@xxxxxxxxxxx> wrote:
> In a more interesting case, if I know that the message has a MIME
> multipart structure, I may "seek" to a certain spot in the file
> to read a certain part, and then the filesystem would download
> that whole part. You have to publish the data for that structure -
> offset, size, MIME type of each part - in file attributes or
> something (note that structure is recursive, by the way!), so
> I would know where to seek. (And we need to test the assumptions
> vs. server implementations and make sure that data is reliable
> and not compromized by differences in the way part sizes are
> reported, separator sizes, etc.)
>
> If it isn't feasible to support random access as described
> above, it still makes sense to support incremental download
> for sequential access. You don't need to download a part until
> I have asked to read it. If I read "off the end" of the cached
> data, but still inside the extent of the file as reported by
> RFC822.SIZE, then it's time to fetch more parts. I don't have
> to know the MIME structure of the file to do this, and of course
> I don't have to communicate it to the filesystem as such, I just
> ask for N bytes of data at file offset T.
>
> I think it will still be desirable to publish MIME structure,
> though, since applications need to know this, and I think you
> really have to support seek anyway, so maybe it boils down to
> the same implementation either way. If the difference is
> whether parts could be incrementally cached out of order, maybe
> that isn't such a good idea anyway, since the part boundaries
> won't line up with the block structure of the cache device.
> Just guessing on that.
From a brief look at a few example multipart mails in my inbox, there isn't any
kind of table of contents referring to the parts; they are simply separated by
a boundary string. So to be able to publish the internal structure of the mail
one would have to parse it completely, which means downloading it completely.
I don't think this kind of pre-parsing of mail content belongs in the file
system, anyway.
CU, Ingo
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