SLO Advanced By Samson Tanimawo, PhD Published Nov 10, 2026 10 min read

Measuring SLOs on Mobile and Edge

If your users are on mobile, your server-side SLO is a partial view. The client-side measurement is the rest.

Why server SLOs miss mobile

Server SLO can show 100% success while every user sees a frozen UI. Network, device, app issues happen between server and user.

Client-side measurement closes the gap.

Four client-side patterns

1. Cold-start time on app launch.
2. Time-to-interactive on key screens.
3. Crash-free sessions.
4. API call success rate measured client-side.

RUM integration

Real-User Monitoring (Sentry, Datadog RUM, Honeycomb mobile SDK) collects from devices.

Sample (cost control) but never zero; long-tail issues live in the long-tail data.

Budget allocation

Customer SLO splits: 60% to server-side, 40% to client-side. The split is opinionated; document.

Each side has owners; debugging crosses the boundary deliberately.

Antipatterns

Server-only SLO for mobile-heavy products. Wrong picture.
Client SLOs without sampling control. Cost.
No correlation server-client failures. Cannot diagnose.

What to do this week

Three moves. (1) Apply the pattern to your most-impactful service. (2) Measure adherence for 30 days. (3) Rewrite the policy or the SLO if the gap is durable.