My current project that I don't understand anywhere near well enough is how to use the Crest API, for pulling market information.
What I used to do.
I had previously used google docs and eve central's API, but google docs are flaky on something as small as my PI spreadsheet, and is unworkable for a full market listing.
What I am currently doing.
I use Steve's python based crest downloader to pull down all buy and sell orders for a region ( https://github.com/fuzzysteve/CREST-Market-Downloader ). I have some success, but what works reliably for him in pulling down an entire region of market orders in 15 minutes, takes 4 hours for me and only works 1/3 or the time.
I also pull down my current asset list and market orders using jeveassets, peeking into both corp and personal assets. Despite having my own division in the corps that I am currently in, I have to filter out 'others' assets from my own. (using sql per below)
While I am no wizard at either Perl or Java, I am very good at SQL. So I upload these 2 data sets and put them into a MariaDB instance (MySQL fork/clone - but much less hassle to download)
Knowing how to map item ids to names, groups, categories and meta levels is useful. For that I use Steve's SDE dump, and as MariaDB/MySQL is my preferred database, https://www.fuzzwork.co.uk/dump/mysql-latest.tar.bz2 works well (other databases and versions in the same folder).
With all of this, a final SQL script can show me, by whatever market group I want to filter on, what my current stock counts are, and what is currently on market, the local price (if any), the jita price, my markup.
When this comes together, it works well. When it doesn't it is a pain.
AlternativesEvernus is a reasonable alternative for some of this functionality and I have looked at it. It is not enough.
I cant work out how to make it show me all the skillbooks missing off the local market, then swap to look at either T1 or T2 ammo, then flit to the next part of the market I am interested in. I have 2 tycoon and 1 wholesale level pilots, but there are 400 different skillbooks alone, and I have less than 700 market slots. If I was better at working out what was needed, I could probably make sure that was there, but have little chance of stocking everything wanted.
I got mildly excited by seeing Evernus Alliance Market ( https://bitbucket.org/krojew/evernus-alliance-market ). It looks to be a good group logistics tool, and despite being written for a Linux environment, with a bit of fiddling, got it installed on a windows instance (there are a couple of evernus 'bug reports' with tips that I found useful ). But .. it too didnt have the functionality I needed, much of which is in Evernus (including a quick crest sales/buy orders download).