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Resilience Pattern Interaction Simulator

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About This MicroSim

This MicroSim simulates Service A calling Service B with three resilience patterns you can toggle — circuit breaker, retry, and bulkhead. Request dots flow across the channel and turn green (success), red (failure), orange (retried), or gray (rejected by the circuit breaker or a full bulkhead pool). You inject failure into Service B and watch the success rate, average latency, circuit-breaker state, and a 60-sample success-rate timeline respond in real time — so the availability/latency interactions of the patterns are observed, not just described.

How to Use

  1. Toggle patterns (Circuit Breaker, Retry, Bulkhead) and adjust their sliders (failure threshold, max retries, pool size).
  2. Inject a failure into Service B: Healthy, Slow (5s responses), Complete Fail, or Intermittent (30% random failures).
  3. Watch the circuit-breaker badge trip from CLOSED → OPEN and later probe in HALF-OPEN; note the countdown to the half-open probe.
  4. Compare the success-rate timeline with the circuit breaker on versus off under Complete Fail, and observe how Retry helps with Intermittent failure but can worsen a Slow downstream.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

<iframe src="https://dmccreary.github.io/atam/sims/resilience-pattern-simulator/main.html"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

Undergraduate / Professional

Duration

20-25 minutes

Prerequisites

Familiarity with circuit breaker, retry/backoff, and bulkhead resilience patterns.

Bloom's Taxonomy Level

Analyze (L4)

Learning Objective

Students will be able to analyze the combined effect of circuit breaker, retry, and bulkhead patterns on availability and latency under a specified failure scenario, and identify which combination best achieves a given availability response measure.

Activities

  1. Circuit breaker value (7 min): Under Complete Fail, students compare success rate and latency with the circuit breaker on vs off and explain the difference.
  2. Retry double-edge (8 min): Under Intermittent failure, students show retry helps; under Slow, they show retry can compound latency (a retry storm).
  3. Combine (6 min): Students find the toggle/slider combination that best holds success rate up under Intermittent failure and justify it.

Assessment

Give students an availability response measure ("≥ 95% success under 30% intermittent failure") and ask them to find and justify a pattern configuration that meets it.

References

  1. Bass, L., Clements, P., & Kazman, R. (2021). Software Architecture in Practice (4th ed.). Addison-Wesley.
  2. Nygard, M. (2018). Release It! (2nd ed.). Pragmatic Bookshelf. (Circuit breaker, bulkhead, timeouts.)