Re: nnir, gnus-goto-article and such

[Andrew Cohen <cohen@andy.bu.edu>]

>>>>> "John" == John Wiegley <jwiegley@gmail.com> writes:


[...]


    John> What doesn't work is that 'A T' doesn't do everything it can
    John> to recursively find all referenced articles from all
    John> refer-article sources.  

The logic used in 'A T' is different from that of 'A R' and friends
because its doing something different. That's not to say that it doesn't
have bugs, and I'm sure that it can be improved. 

    John> In contrast, if you hand-select each article that 'A R' finds,
    John> and then press 'A R' on that, and so on recursively, you will
    John> ultimately end up with the entire thread.  

I don't think this gives the entire thread. It only gives the articles
that precede the article you start with along the current branch. If
there are subsequent articles along the current branch, or articles on
another branch, this recursive procedure won't find them. That's why the
'A T' function tries to do a /search/ for articles rather than just
recursive retrieval. This is complicated by the limitations of the
different kinds of servers. 


Here is the complete `A T' logic for nntp and nnimap groups:

1. nntp: The nntp protocol has no searching capabilities at all, so
   there is no way to search by message-id. Gmane has a Xapian-powered
   search engine written by Olly Betts that works very well, but doesn't
   allow searching by message-id. What gnus does in this case is very
   primitive: it retrieves the headers for a (configurable) number of
   articles before and after the current article (250 before and 250 after
   by default) in the current group, and then gnus itself searches within
   these headers for articles belonging to the thread. But there is no way
   to know if there are other articles in the thread in other groups or on
   other servers.

2. nnimap: The imap protocol allows searching by headers, but only
   within a single group. So by default if you `A T' on an article in an
   nnimap group a search will be performed for all the articles that
   might be in the thread in the current group only. 

   Recently I added the ability to replace this search with an nnir
   search which will look for articles in the thread on the whole server
   rather than just in the current group. But it won't look outside the
   server. 

   I have also recently re-written much of nnir, but I won't push it
   until after the freeze is over. As part of this re-write, when
   searching for a thread on the whole server the registry is consulted
   to see what group the article on which you invoke `A T' came from,
   and consult /both/ that server and the server containing the current
   group. This is a very minor improvement, since most of the time these
   two servers will be the same. 

I guess we can consult the registry for all the articles mentioned in
the references header and see if any of those articles came from
different servers and search those servers as well. But if they are nntp
servers we can't really search them effectively (since nntp doesn't have
search facilities). We could also configure this to /always/ search a
particular set of servers independently of where the proximate article
came from.

Best,
Andy