After downloading charts
, I noticed that the NOAA website offers two XML files (ENC
) that they describe as being useful to fetch only the changed charts
That sounded like a nifty idea: write a script that checks for updates to the charts that I have downloaded. But what of newly added charts? Should I care? This would be more of an intellectual exercise, as I just sail around the NYC
area, but still it would be nice to always have fresh charts. I would release this under a GPLv2 license
I started to look at these NOAA XML files, and honestly I think they offer more data than I need. I see scads of metadata about the charts, such as bounding polygons, "nm update agency", etc. What I would like to do is simply refresh the charts I already have, perhaps broken down by some sort of convenient grouping like coast guard district. Ideally I guess bounding longitude / latitude would be best but I'll bet that a tough nut.
I may simply skip all XML parsing and crawl the directory and save timestamps for the charts I have. I googled a bit, but I found no data dictionary for these XML files explaining each field. Does such a document exist?
It reads like this:
Product Catalog</gco:CharacterString> *Finally*
I see some related data definitions here
, but I think I am headed in the wrong direction.
Honestly with disk space so cheap
it would seem simpler just to grab everything that is newer than the files I already have.