Turn alma marc-xml export files into nicer marc-in-json jsonl files
Alma exports marc-xml files as a bunch of <whatever>.tar.gz files, each of which has the single file <whatever>.xml in it.
This is code that creates a fat .jar (i.e., all dependencies included) that will take any number of <whatever>.tar.gz files and produce
<whatever>.jsonl.gz files in the directory you invoked the program from.
This is an executable .jar file that only takes filenames to convert as arguments.
java -jar /path/to/alma.tar.gz-to-marcinxml /path/to/alma/*.tar.gz
It's not ridiculously fast (e.g., it doesn't use Jackson custom serializers like it should and isn't even multi-threaded), but it'll convert the University of Michigan's full export of some 14.5M records on my laptop in about 15mn.