Avoid round trips to internal servers
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Centralizing experiment assignment on an internal server can lead to performance issues and poor user experience. Eppo's client-side SDKs work best when they can evaluate assignments locally without additional network calls.
What Happens With Internal Server Round Trips
When implementing centralized experiment assignment on internal servers, you'll face two main challenges:
Performance Impact:
- Each call to the server adds latency for each flag evaluation
- Additional server load and maintenance
- More complex application architecture
Implementation Compromises:
- Pressure to implement "fetch all flags at initialization"
- Potential conflicts with other best practices
- Reduced quality of analytic data
Best Practice
Use Eppo's client-side SDKs for most use cases. They:
- Pre-fetch obfuscated flag configurations
- Perform assignment logic locally
- Evaluate flags only when features are rendered
- Typically complete round trips in under 20ms
Exception Cases
Server-side assignment can be useful in the following cases:
- Experiences originate from the backend
- A/B testing machine learning models with server-side predictions
- Other scenarios requiring server-side logic
If you need to remove the CDN dependency entirely, you can fetch Eppo's configuration file independently and pass it to the client during app initialization. See our deployment modes documentation for details.