The chain asked three registers and returned whichever answered first
with a title and an author, discarding the rest. The registers are
complementary rather than redundant: OpenLibrary's edition record
carries the publisher, the pagination and the language and names its
authors by key, while its search index carries the authors and not the
publisher. One book, two half-answers, and the whole of it only if they
are put together.
They are merged now, first answer winning each field, so the order of
the chain is the order of trust. The record says which registers spoke.
It also carries what was being thrown away: subjects, language and a
page count, from whichever register has them. The index will not return
those unless asked for by name, which is how a language it held went
unread. Subjects are capped at twelve — the index lists every heading
every edition of a work has ever been given, which on a well-known book
is hundreds.
An edition record keeps its subtitle in a separate field, so a title
came back without it.
book-pipeline reaches for colophon and bibfetch on every book it repairs.
Shelling out would mean a process per book per tool across five thousand
books, and parsing back the JSON it is about to parse anyway.
bibfetch's fetch loop lived in main.rs, so binding it meant either
lifting it or writing a second one. A second implementation of 'which
register answers about this kind of identifier, and in what order' would
drift from the first, and the copy nobody runs from a terminal would
drift silently. It is now bibfetch::ask, and the command line calls it
too — verified by running the CLI before and after and diffing.
fetch_identifier releases the GIL around the request. It is the only
function here that opens a socket, and holding the interpreter for the
length of an HTTP call would stop every other thread in it.
bibfetch is optional and only the python feature turns it on: its HTTP
client does not build for wasm32, and an unconditional dependency would
have taken the JavaScript package down with it.
funkpower