Things I Learned From Working A 2 Year 50,000 Line Project

This is mostly to serve as a brain dump for a piece of software I've been writing for around two and a half years, it was comprised of a large database (read: ~five hundred million rows), a cross platform Java application, a large Python web-server/API, a phone app, lots of small scripts that fetched and transformed data, and globs of glue. (I wrote all of them in the two year period!)

Architecture

• It pays to fully think through your APIs first
• All web APIs should have a version in the URL e.g. /application/api/2.0/...
• Profile early and often
• A few good caches are worth many bad ones
• Make everything a plugin that extends one class; you may think it's a big hairy mess, but it's better than multiple plugin systems.
• Use libraries wherever possible
• Ditch libraries when you only use one function from them

Debugging

• Users write awful bug reports
• You can help them write better ones by giving them a short form to fill out.
• Automatically attach debugging info to all bug reports
• Make version numbers easily available (not just in the executable's name)
• Auto-update your apps so you don't have users lagging behind

Upgrades

• Your requirements will constantly change, make sure you have an easy upgrade path in your database that won't force hacky solutions.
• Make sure your ORM supports incremental changes.

User Experience

• Start fast, even if you're not done processing yet
• Never trust an engineer to do design (including software engineers)
• If the user doesn't see it, it doesn't exist
• Make it very hard for the user to do stupid things
• Do automatic backups/saves

Sanity

• Clients like saying "I did say that, didn't I? What I meant was..."
  • all features should be plugins so you can enable/disable when they do this
• SVN and Eclipse are a nightmare to get playing nice
• Java 7 is really awesome!
  • auto-closing streams
  • multiple catches in a try block
  • string in switch statements
• JNLP sucks, but so does embedding apps in-browser; just make it easy for the user to download it, and provide auto upgrading