APNs and FCM allow content-available or high-priority flags to wake apps sparingly for quick syncs. Keep payloads tiny, encrypt sensitive fields end-to-end, and prefer fetching deltas after receipt. Respect platform quotas, coalesce bursts, and avoid notification spam by routing low-importance events into discreet badges or inboxes. Silent pushes shine for state refreshes without user disturbance.
When push is unavailable, smart polling works surprisingly well. Negotiate freshness with ETags or If-Modified-Since, and request only what changed. Increase intervals during idle periods, apply exponential backoff after errors, then shorten briefly upon user activity. Combine pagination cursors with lightweight checksums to confirm integrity. The result is reliable, understandable behavior that gracefully respects bandwidth and compute.
SSE excels for one-way streams with minimal overhead and graceful reconnection, while WebSockets handle bi-directional chatter and high-frequency updates. Beware corporate proxies, mobile radio churn, and tab throttling. Use heartbeat frames, ping-pong liveness probes, and message framing that supports resumption via last-event-id or sequence numbers. Instrument reconnect reasons to learn which environments actually need tuned fallbacks.
Every network request can trigger expensive radio transitions and tail times. Group calls, piggyback on existing connectivity, and reuse persistent channels where appropriate. Align background work with platform-maintained maintenance windows. Prefer fewer, larger transfers over many tiny bursts. Instrument per-session energy impact, not just server metrics, so you see the real cost paid by your users’ devices.
Send only what changed, version your schemas, and compress payloads with formats suited to your data shape. Use strong validation with ETags, short circuit 304 responses, and cache immutable assets aggressively. Keep server-driven expirations consistent so clients avoid jittery refetch patterns. Carefully model worst-case paths to ensure bandwidth savings hold during outages, retries, and rapid reconnects.
Respect Doze, App Standby, and iOS background task limits. Use WorkManager, JobScheduler, and BGTaskScheduler to defer non-urgent work. Silent push is not a guarantee; always handle absence gracefully. Declare precise capabilities, minimize foreground services, and build health checks that detect throttling. Design fallbacks that maintain correctness first, then recover speed when the system grants opportunities.
Pair a responsiveness target with an attention-protection target. For example, P95 message-to-visibility under three seconds, while weekly interrupt minutes per user remain below a strict threshold. If one improves while the other worsens, you are mortgaging goodwill. Publish both to dashboards and on-call runbooks so teams optimize holistically rather than chasing lopsided wins.
Event streams should capture timing, channel, and outcome without exposing content. Hash identifiers, aggregate early, and sample where detail is unnecessary. Store raw data briefly, then roll into cohorts for long-term analysis. Provide a data export path for users who ask. Insight grows when everyone trusts how measurement happens and why it exists.