Comment 5 for bug 340203

Hi Book Processing,

We plan to scan some books right-to-left.

Hank wrote up what i think is a good plan for doing this;
i copied it into the bug report for this project:
    https://bugs.launchpad.net/scribe2/+bug/340203

The big picture is:
   (a) loader determines whether book is left-to-right
       (English) or right-to-left (Arabic, Hebrew, Korean, etc)
   (b) loader indicates this to biblio tool
   (c) scanner scans book either left-to-right or right-to-left
       as indicated by the biblio tool.

This means that the piece of info (one bit, indicating whether
it is a right-to-left book or not) has to make its way from
(b) [the loader station] to (c) [the scanner station].

There are two commonly used ways this could happen, as far as i know:
   (i) through the metadata table directly
  (ii) via the archive (as in, loader writes to the item, scanner
       reads it out).

As far as i know, all communication of this sort currently
goes through path (i).

However, to send this new information through path (i) would
take a new column in the metadata table (or a take-over of an
existing one).

Path (ii) has the problem of making a call on the item in the
archive, which adds a point of failure (although we'll do it
only once), and this point of failure affects all books
whether right-to-left or left-to-right.

However, i'm planning on doing that anyway, because adding columns
to the metadata table is so problematic.

To reduce the probable failure rate, i intend to add a configuration
flag so that this code will only execute at scancenters or on scribes
where we know right-to-left scanning will be done.

If anybody objects, or has other possibilities in mind, please
reply before about 2:00 Wednesday, 3/18/2009. (I have to be gone
Wednesday morning, but in the afternoon i plan to be here and
pursuing path (ii). The first half of Hank's plan is done, i.e.,
the pipeline is already laid from biblio to the metadata, and
getting it back out starts tomorrow afternoon i hope.)

dan