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.

1. ERRORS ERRORS
EVERYWHERE!
@dpokusa

2. Microservices
CQRS
Queues
Hexagonal
SOA
Serverless
Event Sourcing
Integrations
Pipe-Filter
Event BUS
EDA

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

19. ISSUES TAGS
RETRY!

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;
}

25. TAGSISSUES
F D
A
G E
H

26. TAGSISSUES
F D
A
G E
H

27. TAGSISSUES
F D
A
G E
H

28. TAGSISSUES
F D
A
G E
H

29. TAGSISSUES
F D
A
G E
H

30. TAGSISSUES
F D
A
G E
H

31. TAGSISSUES
F D
A
G E
H
CIRCUIT
BREAKER

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

36. System.exit(500);

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
}
}

42. TAGSISSUES
F
D
A
G
E
H
QUEUE

43. ISSUES TAGS

44. ISSUES TAGS
4XX

45. ISSUES TAGS
5XX

46. TAGSISSUES
F
D
A
G
E
H
QUEUE

47. Hospital
QUEUE

48. TAGSISSUES
F
D
A
G
E
H
QUEUE
QUEUE

49. ROLLBACK
&
LEAVE

50. TAGSISSUES
F
D
A
G
E
H
QUEUE

51. TAGSISSUES
F
D
A
G
E
H
QUEUE

53. TAGS
ISSUES PROJECTS D
E
D

54. TAGS
ISSUES PROJECTS D
E
D
H

55. TAGS
ISSUES PROJECTS D
E
D
H

56. BULKHEAD

59. DOMAIN ERRORS

60. CBA E
QUEUE

61. CBA E
QUEUE
CBA E

62. Compensating
TRANSACTION

64. CBA E
QUEUE

65. CBA E
QUEUE
SASSTORE
SCHEDULER

66. CBA EQUEUE
SASSTORE
SCHEDULER

67. CBA E
SASSTORE
SCHEDULER

68. Scheduler
Agent
Supervisor

70. ABOUT
software-empathy.pl
@dpokusa

71. @dpokusa
ABOUT
08.09.2018
SPREADIT.PL

72. Q&A