Artio is a high-performance FIX and FIXP Gateway.

1. Overview (best place to start!)
2. Codecs
3. Session Management
4. API Design
5. Replays
6. Performance and Fairness
7. Operational Concerns
8. Threading Model
9. FIX Implementation Choices
10. Frequently Asked Questions
11. Supporting Multiple FIX versions
12. Uploading to Internal Maven Repositories
13. Session MetaData
14. Cancel On Disconnect Notification

1. FIXP Support
2. iLink3 Support
3. BinaryEntryPoint Support

If you're interested in the overall Design Principles for development then take a look at the Aeron document on that topic

1. Architecture
2. Logging Module
3. Benchmarking
4. Reference Implementation