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Module 16 Cheat Sheet

OBSERVABILITY
=============

Logs
  what happened

Metrics
  how often/how much

Traces
  where request spent time


CORE SIGNALS
============

traffic
errors
latency
saturation


LATENCY
=======

measure:
p50
p95
p99

break down:
Mule
Salesforce
HTTP APIs
DB
queue wait


CORRELATION
===========

correlationId
= transaction

customerId
= business entity


TIMEOUTS
========

derive from
overall latency budget


RETRIES
=======

bounded
backoff
idempotent

watch for:
retry storms

monitor retry rate


SALESFORCE
==========

watch:
latency
timeouts
limits
locking
API usage


ASYNC
=====

queue depth
oldest message age
DLQ
processing lag


BATCH
=====

processed
failed
records/sec
duration
Bulk job status


ALERTING
========

alert on meaningful thresholds
not every individual error


TROUBLESHOOTING
===============

“Mule is slow”
↓
find exact latency segment
↓
check downstream
↓
check retries
↓
check saturation
↓
check traffic
↓
check deployment changes

One interview sentence worth memorizing:

“I don't troubleshoot ‘Mule is slow’ as one black box. I decompose the request into Mule processing, downstream latency, retries, queueing and resource saturation, use correlation IDs to trace individual requests, and monitor p95/p99 plus dependency-specific metrics so I can identify the actual bottleneck rather than tuning blindly.”

And one current detail you can casually mention if observability comes up: Mule Runtime 4.12 added OpenTelemetry metrics support to Direct Telemetry Stream, so Mule telemetry can increasingly fit into enterprise-wide OpenTelemetry observability strategies.

Next is Module 17 — Interview System-Design Scenarios. Instead of introducing many new concepts, we'll put everything together and practice 5–6 realistic prompts like “build Mule → Salesforce customer sync,” “500k nightly records,” “Salesforce outage,” “Account + Contacts + Billing orchestration,” and “event-driven Salesforce updates.” This is where I'd focus heavily because it's likely closest to what they'll actually ask you.