Resilience Design Patterns

How does your system react if a key resource fails? The database becomes unavailable or the message broker fails? What if you get a current surge of load that you have to keep up? Real life and other engineering disciplines can teach us a thing or two on software design and what it means to be reliable.

Learn useful techniques and patterns that you can borrow from other areas of engineering and see how to apply them in your systems to make it more reliable.

Transcript

1. RESILIENCE DESIGN PATTERNS @indu_alagarsamy
2. Photo Credit: Roger Taylor
3. Source: https://www.climbing.com/places/itraitor-horn-i5-8-four-pitches-tahquitz-rock-idyllwild-california/
4. Source: https://www.climbing.com/places/itraitor-horn-i5-8-four-pitches-tahquitz-rock-idyllwild-california/
5. DESIGNING FOR SAFETY @indu_alagarsamy LESSONS FROM ROCK CLIMBING
6. SOLID REDUNDANT EQUALIZED NO EXTENSION @indu_alagarsamy
7. SOLID @indu_alagarsamy
8. REDUNDANT @indu_alagarsamy
9. EQUALIZED @indu_alagarsamy
10. NO EXTENSION @indu_alagarsamy
11. DESIGNING FOR RESILIENCE @indu_alagarsamy LESSONS FROM ELECTRICAL ENGINEERING
12. Source: https://www.kayserelectricals.com
13. CIRCUIT BREAKER PATTERN
14. class CircuitBreaker Properties: - string: name of the operation - int: MaxTimesToRetry - TimeSpan: DelayBetweenRetries - Action<Exception>: Action to invoke when the circuit breaker is tripped Methods: - Reset() - Trip (Exception Ex) @indu_alagarsamy
15. var circuitBreaker = new CircuitBreaker( "CheckServiceConnection", 3, Timespan.FromSeconds(1), action => { WriteLine("Circuit breaker tripped - failfast"); FailFast(connectionException.Message); }); @indu_alagarsamy
16. public void When_the_circuit_breaker_is_tripped_the_trip_action_ is_called_after_reaching_max_threshold() { var connectionException = new Exception("Something bad happened."); circuitBreaker.Trip(connectionException); System.Threading.Thread.Sleep(5000); Assert.IsTrue(circuitBreakerTripActionCalled); } @indu_alagarsamy
17. public void When_the_circuit_breaker_is_reset_the_trip_action_is _not_called() { var connectionException = new Exception("Something bad happened."); circuitBreaker.Trip(connectionException); System.Threading.Thread.Sleep(1000); circuitBreaker.Reset(); Assert.False(circuitBreakerTripActionCalled); } @indu_alagarsamy
18. DESIGNING FOR RESILIENCE @indu_alagarsamy LESSONS FROM THE REAL WORLD
19. Cashier Barista MakeTheDrink(drinkSpecs); drink object ProcessCharge(); return drink; OrderDrink(); Temporal Coupling
20. DrinkOrdered CustomerDrinkPrepared Cashier Barista OrderDrink Publish - Subscribe
21. DESIGNING FOR RESILIENCE @indu_alagarsamy LESSONS FROM CONTROL SYSTEMS ENGINEERING
22. Source: Gareth James, https://flickr.com/photos/ gareth_james_fi/ https://creativecommons.org/licenses/by-nc/2.0/
23. Source:corgi-homeplan-how-safe-is-your-home.org/
24. PROCESS VARIABLE SET POINT @indu_alagarsamy Desired value for the variable, eg. 25 Celsius Current measured value of a process that is being monitored or controlled. E.g. 23 Celsius ERROR VALUE Difference between the Set Point and the Process Variable
25. REFACTORING TOWARD DEEPER INSIGHT @indu_alagarsamy
26. Source: https://www.apnews.com/73404d09773740f699d4b92933abec50
27. https://www.nytimes.com/interactive/2019/07/16/world/europe/notre-dame.html FEU ATTIC NAVE SACRISTY ZDA-110-3-15-1 ASPIRATING FRAMEWORK @indu_alagarsamy
28. NO FIREWALLS NO SPRINKLERS STONE CEILING WINDING STAIRS Source: https://www.nytimes.com/interactive/2019/04/17/world/ europe/notre-dame-cathedral-fire-spread.html RISKS @indu_alagarsamy
29. WHEN YOU EXPECT MIRACLES FROM THE SYSTEM, YOU’RE IN FOR A BROKEN HEART - JOHN LONG Picture Source: https://www.piquenewsmagazine.com/whistler/the-life- advice-john-long-gave-me-before-he-forgot-my-name/Content? oid=7931226 @indu_alagarsamy
30. https://indu.dev RESOURCES https://particular.net/blog/protect-your-software-with- the-circuit-breaker-design-pattern https://www.infoq.com/presentations/controllers-observing-systems/ @indu_alagarsamy THANK YOU Domain-Driven Design - Tackling Complexity in the Heart of Software by Eric Evans https://www.infoq.com/presentations/pid-loops/