How do you share configuration information or business rules between languages

Question

I'm looking for best practices for using the same data in different places without repeating yourself - this could include configuration or business rules.

Example 1. Data validation rules where you want to validate on the client using javascript, but you want to make sure by validating on the server.

Example 2. Database access where your web server and your cronjobs use the same password, username.

Ease of processing and a human-readable solution would be a plus.

Teodora

This isn't "configuration" in the usual sense. This is code. Please drop "configuration" and put "code" or "business rules" or something else in the question. – Nosography

I've added business rules to title and tags, but I think configuration applies to the second example. MySQL, for example, refers to its .my.cnf files (with user, password, host, etc) as configuration files. – Teodora

Answer 1

Encode your data in JSON. There's a JSON library for pretty much any language you'd care to think of, or if not, it's pretty easy to code one up. If JSON is not enough, perhaps look at YAML.

Glendon

I think this works well only for Example 2 (data), not for Example 1 (logic). – Rob

If you want to be totally language-agnostic, you will have to encode the logic in some sort of data anyway. Of course you could go all the way and use Lisp S-expressions, so your code is data. :-) – Jame

Thanks Jouni - sorry for the late acceptance. I was holding out for something that would handle example 2 as well, but yours is a good fit for now. – Teodora

Answer 2

XML is pretty globally used. Easy to read, easy to write, and human readable. If you're concerned about the space overhead (which you actually aren't if you want human readable) then just compress it before you send it out, XML compresses quite well.

Careen

Text files all generally compress well. – File

Answer 3

See answers to this question. I think they are applicable here, especially the one with a DSL.

Chapbook

Answer 4

As much hate as they get, for sharing data validation rules, I'm going to have to say Regular Expressions.

I know, I know, everyone hates them, but they are (generally) language-agnostic.

Bamako

They're language-agnostic, only if you use a small subset of features. – File

Answer 5

1. Use O/S Environment Variables (envvars) to store application configuration info (such as db passwords)

2. Validation rules often require logic. You could write your rules in JavaScript, and then run them in the browser, server (using Nashorn), and database (PLV8 with Postgres).

Photoelectric