How to parse a GDB (Geodatabase) file in Ocaml?

[abhsrivastava]

I am thinking of developing a hobby project where I downloaded all the trails in Washington state in the form of a GDB file (Geodatabase) and I want to query the weather API on those trails to see which trails can be hiked when.

But for this I need to parse a Geodatabase file. I can see the specification is here https://github.com/rouault/dump_gdbtable/wiki/FGDB-Spec but is there an easy way to parse this in ocaml?

[patricoferris]

Hi @abhsrivastava,

Thanks for opening this discussion! This sounds really cool.

I did a little bit of looking around and it looks like parsing Geodatabase files is going to be tricky because they're proprietary. However, as you point out, people have reverse-engineered it. The format looks very "packet-like" so I think you can manage everything with either Cstruct or if you want to use the bleeding-edge, Eio. For example, here are the big-endian combinators https://ocaml-multicore.github.io/eio/eio/Eio/Buf_read/BE/index.html and here's some docs on using the Buf_read API https://github.com/ocaml-multicore/eio#buffered-reading-and-parsing.

I do wonder if you can get the same trails data in a different, open format? Something like GeoJSON, Shapefile, GML or KML? (Or maybe even export it into that format)

[abhsrivastava]

Let me look if there are alternate formats available somewhere. I did a google search and landed on the Washington state government website https://geo.wa.gov/search?q=%20trails everything there seems to be tied to ArcGIS formats.