all pieces are stored in a db and the user can change the connection btn the datapoints between different metrics such as date or popularity.

Juliette Melton and I were also talking about this at the tools of change conference in NYC.

We also wanted to take it up a notch and allow people to vote on and tag threads as well so that really good ones could migrate easily into FAQs and knowledge bases.

GNU Mailman: http://www.list.org
Mailman wiki: http://wiki.list.org

I usually use quoting to indicate precisely what part of a message I’m responding too — actually, one of my gripes about a lot of web-based forum software is that it usually doesn’t paste in the original message (with “>” or other reply markers) automatically, thus making quoting more work than it needs to be. (For example, my blog’s comment software doesn’t give me quote marks for the comment I’m following up to; if it had, I would have done so here.)

Gmane’s forums get it right, though: if you choose the ‘followup’ action, it’ll provide you with the quoted message, email-style.

I couldn’t find a forum at Gmane but I found some very interesting things. First, they have a threading diagram just like the one CompuServe used to use. I’m very comfortable with that and it effectively turns the mailing list into a forum format confirming what you said:

Conversational threads on the Internet should be independent of the medium they’re displayed in. That is, mailing lists, newsgroups, and web forums are all the same thing. They’re just different interfaces to the same data structure, and that data structure is the thread: a series of messages with directional reply relationships to one another.

The one difference that stood out is that in a forum you don’t need to quote as much as when replying to email since you are already following the thread and, when in doubt, you can always bring up the original instantly.

Second, I chanced on a discussion about mailing lists vs. forums

http://thread.gmane.org/gmane.comp.emulators.wine.devel/57000/focus=57072

CompuServe forums had beautiful threading and you could keep the data on your own machine, a necessity back then because connections were slow and expensive. When I first tried a web forum it was ten steps back from CompuServe and my first web project was to reproduce the CompuServe threading on the web. Unfortunately, my web programing skills back then were not up to the task and I had to abandon it.

A thread is really just a tree with links back and forth between parent and child. Siblings are ordered by age (ascending Id will do).

I have yet to see a web forum implement proper threading, the closest I have seen is The Motley Fool discussion boards and that is proprietary code and the messages are practically unsearchable.

One thing to keep in mind is potential multi-parent situations. Email headers got this all worked out years ago: they’ve got the ‘Message-ID’ header to give every message object in the universe a unique identifier (but see below about ‘Supersedes’); the ‘References’ header to indicate all the messages (or at least the first and last-so-far) in the thread preceding this one; the ‘In-reply-to’ header to indicate which message this one is replying to; and the (I think rarely used) ‘Supersedes’ header (sometimes apparently called ‘Replaces’) for when you need to have a new version of an already-posted message.

I don’t think ‘In-reply-to’ is supposed to ever list multiple IDs, but you could have a situation in which there is only a ‘References’ header and no ‘In-reply-to’. Also, nothing prohibits cycles, as far as I know: message A can be in-reply-to message B which is in-reply-to message C which is in-reply-to A.

None of these things are showstoppers, though. I do think it’s important to separate message body storage from the thread structure. All the relationships here are represented in the metadata: the message bodies could be absent entirely, yet the relationships would still be the same.

The idea of a “one true thread” may be dangerous. Email and news headers are arranged so that newly-encountered messages can be incorporated into a given thread store. It may be that no single archive has all the messages in a particular thread — in fact, incompleteness could be the common case. For example, if I reply privately to a public mailing list post by you, only you and I have the reply, but it’s still part of that thread.

So although the thread is the fundamental unit, it’s also a very amorphous one…

I found these pages useful:

Message Threading in E-mail Software

List of mail & news headers

Wikipedia section on email headers