Errors errors, everywhere! - JSession
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The document discusses various distributed system patterns and concepts including microservices, CQRS, event sourcing, queues, circuit breakers, and retries. It also mentions fallacies of distributed computing and the CAP theorem. There are code examples for implementing retries and circuit breakers in Java as well as health checks. Distributed system issues like errors, timeouts, and failure recovery are also addressed.
Errors errors, everywhere! - JSession
- 3. A B C
- 4. A B QUEUE C
- 6. The fallacies of distributed computing L. Peter Deutsch and other “Sun Microsystems Fellows”
- 7. 1)The network is reliable.
- 8. 1)The network is reliable. 2)Latency is zero.
- 9. 1)The network is reliable. 2)Latency is zero. 3)Bandwidth is infnite.
- 10. 1)The network is reliable. 2)Latency is zero. 3)Bandwidth is infnite. 4)The network is secure.
- 11. 1)The network is reliable. 2)Latency is zero. 3)Bandwidth is infnite. 4)The network is secure. 5)Topology doesn't change.
- 12. 1)The network is reliable. 2)Latency is zero. 3)Bandwidth is infnite. 4)The network is secure. 5)Topology doesn't change. 6)There is one administrator.
- 13. 1)The network is reliable. 2)Latency is zero. 3)Bandwidth is infnite. 4)The network is secure. 5)Topology doesn't change. 6)There is one administrator. 7)Transport cost is zero.
- 14. 1)The network is reliable. 2)Latency is zero. 3)Bandwidth is infnite. 4)The network is secure. 5)Topology doesn't change. 6)There is one administrator. 7)Transport cost is zero. 8)The network is homogeneous.
- 15. CAP THEOREM Eric Brewer, 1998
- 16. PACELC theorem Daniel Abadi, 2010
- 17. SAFE TO FAIL
- 18. ISSUES TAGS
- 20. C B F D A G E
- 21. C B F D A G E RETRY! MAX ATTEMPTS Backoff POLICY RECOVER
- 22. RETRY! @Service public interface MyService { @Retryable( value = { SomeException.class }, maxAttempts = 2, backoff = @Backoff(delay = 5000)) void retry(String message) throws SomeException; @Recover void recover(SomeException e, String message); }
- 23. RETRY! @Bean public RetryTemplate retryTemplate() { RetryTemplate retryTemplate = new RetryTemplate(); FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy(); fixedBackOffPolicy.setBackOffPeriod(1000l); retryTemplate.setBackOffPolicy(fixedBackOffPolicy); SimpleRetryPolicy retryPolicy = new SimpleRetryPolicy(); retryPolicy.setMaxAttempts(15); retryTemplate.setRetryPolicy(retryPolicy); return retryTemplate; }
- 32. CIRCUITBREAKER @Service public class JSessionService { private final RestTemplate restTemplate; public JSessionService(RestTemplate rest) { this.restTemplate = rest; } @HystrixCommand(fallbackMethod = "fallback") public String jsessionRecommendations() { URI uri = URI.create("http://localhost:8092/recommended"); return this.restTemplate.getForObject(uri, String.class); } public String fallback() { return "Errors, errors everywhere!"; } }
- 34. ISSUES DB TAGS
- 35. DIE
- 37. @Component public class HealthCheck implements HealthIndicator { @Override public Health health() { int errorCode = check(); if (errorCode != 0) { return Health.down() .withDetail("Error Code", errorCode).build(); } return Health.up().build(); } public int check() { return 0; } }
- 38. @Component public class HealthCheck implements HealthIndicator { @Override public Health health() { int errorCode = check(); if (errorCode != 0) { return Health.down() .withDetail("Error Code", errorCode).build(); } return Health.up().build(); } public int check() { return 0; } }
- 39. { "status" : "DOWN", "myHealthCheck" : { "status" : "DOWN", "Error Code" : 1 }, "diskSpace" : { "status" : "UP", "free" : 209047318528, "threshold" : 10485760 } }
- 43. ISSUES TAGS
- 44. ISSUES TAGS 4XX
- 45. ISSUES TAGS 5XX
- 47. Hospital QUEUE
- 49. ROLLBACK & LEAVE
- 56. BULKHEAD
- 59. DOMAIN ERRORS
- 60. CBA E QUEUE
- 64. CBA E QUEUE
- 72. Q&A