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UNBREAKABLE REST APIs Desenhando e implementando APIs robustas e previsíveis com fail fast e idempotency Rafael Ponte | @rponte

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CACHE

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PROCESSAMENTO ASSINCRONO CACHE

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BALANCEAMENTO DE CARGA CACHE PROCESSAMENTO ASSINCRONO

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Se você não tem requisitos de desempenho ou throughput então você não tem problema de escala.

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Microservices não existem para escalar aplicações, mas sim para escalar times.

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https://www.youtube.com/watch?v=GBTdnfD6s5Q

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https://www.youtube.com/watch?v=GBTdnfD6s5Q “ Eu não escrevi um livro sobre microservices, mas sim sobre como você arquiteta para Entrega Contínua. ” — Sam Newman

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@duffleit Simple System

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@duffleit Complicated System

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@duffleit Complicated System

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@duffleit Complicated System

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@duffleit Complicated System 🔴

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@duffleit Complicated System 🔴

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Un·cer·tain·ty

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O que é um Sistema Tolerante a Falhas?

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https://deniseyu.io/art/

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https://deniseyu.io/art/

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https://deniseyu.io/art/

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Desenhando sistemas distribuídos…

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Spring Boot App

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Spring Boot App

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Spring Boot App Client Service

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Spring Boot App Client Service

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Spring Boot App Client Service Local Calls

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Spring Boot App Client Service Local Calls

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Spring Boot App Client Service Local Calls

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Spring Boot App Client Service Local Calls Mas não aqui!

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Spring Boot App Client Service Local Calls Mas não aqui!

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Spring Boot App Client Service Local Calls

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Em contrapartida…

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Spring Boot App Spring Boot App

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Spring Boot App Spring Boot App Client

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Spring Boot App Spring Boot App Client Service

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Spring Boot App Spring Boot App Client Service Internet

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Spring Boot App Spring Boot App Client Service Internet

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Spring Boot App Spring Boot App Client Service Internet Remote Calls

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Spring Boot App Spring Boot App Client Service Internet Remote Calls

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Spring Boot App Client Spring Boot App Service Internet Remote Calls

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Spring Boot App Client Spring Boot App Service Internet Remote Calls

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Spring Boot App Client Spring Boot App Service Internet Remote Calls

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Spring Boot App Client Spring Boot App Service Internet Remote Calls

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Spring Boot App Client Spring Boot App Service Internet Remote Calls

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Spring Boot App Spring Boot App Internet Client Service Remote Calls

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https://deniseyu.io/art/

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https://deniseyu.io/art/

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https://deniseyu.io/art/

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https://deniseyu.io/art/

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https://deniseyu.io/art/

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Por que isso importa?

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Spring Boot App Spring Boot App Spring Boot App Local Calls Remote Calls

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Spring Boot App Spring Boot App Spring Boot App Centralized System Distributed System

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Spring Boot App Spring Boot App Spring Boot App Centralized System Distributed System

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— Martin Fowler First Law of Distributed Object Design: "don’t distribute your objects"

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Mas se não tiver jeito…

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Spring Boot App Client Spring Boot App Service Internet Distributed System

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Spring Boot App Client Spring Boot App Service Internet Distributed System

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Distributed System Spring Boot App Client Service Internet Database

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Distributed System Spring Boot App Client Service Internet Database

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Distributed System Spring Boot App Client Service Internet Database

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } } Injetado pelo Spring!

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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Design for Failures

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@rponte Rafael Ponte Brazilian Software Engineer at aka Prince of the Ocean aka Maharaja of the Legacies 19+ years of experience working with Java and distributed systems Loves working with "boring techs"

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Fortaleza - Terra do Sol

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?

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?

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UNBREAKABLE REST APIs Desenhando e implementando APIs robustas e previsíveis com fail fast e idempotency Rafael Ponte | @rponte

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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O que acontece quando esperamos demais?

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Tudo isso porque esperamos demais…

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Fail Fast

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Fail Fast with timeouts

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Não con fi e no timeout default dos frameworks

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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@Repository public interface UserRepository extends JpaRepository { @QueryHints({ @QueryHint(name = "javax.persistence.query.timeout", value = "2000") }) @Override public Optional findById(Long id); }

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@Repository public interface UserRepository extends JpaRepository { @QueryHints({ @QueryHint(name = "javax.persistence.query.timeout", value = "2000") }) @Override public Optional findById(Long id); }

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@Repository public interface UserRepository extends JpaRepository { @QueryHints({ @QueryHint(name = "javax.persistence.query.timeout", value = "2000") }) @Override public Optional findById(Long id); }

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@Repository public interface UserRepository extends JpaRepository { @QueryHints({ @QueryHint(name = "javax.persistence.query.timeout", value = "2000") }) @Override public Optional findById(Long id); }

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@Repository public interface UserRepository extends JpaRepository { @QueryHints({ @QueryHint(name = "javax.persistence.query.timeout", value = "2000") }) @Override public Optional findById(Long id); }

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@Repository public interface UserRepository extends JpaRepository { @QueryHints({ @QueryHint(name = "javax.persistence.query.timeout", value = "2000") }) @Override public Optional findById(Long id); }

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@Repository public interface UserRepository extends JpaRepository { @QueryHints({ @QueryHint(name = "javax.persistence.query.timeout", value = "2000") }) @Override public Optional findById(Long id); }

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Quando a query demorar mais do que 2 seg…

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SELECT u.* FROM user u WHERE u.id = 42 -- SQL Error: 0, SQLState: 57014 -- ERROR: canceling statement due to user request

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Service Network Database Client Spring Boot App

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O que acontece quando o cliente recebe um erro de timeout?

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Un·cer·tain·ty

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Client Service Network Database Spring Boot App

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Como seu sistema se comporta quando o cliente re-tenta uma chamada?

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@RestController public class FindUserController { @Autowired private UserRepository repository; @GetMapping("/api/users/{id}") public ResponseEntity> findById(@PathVariable Long id) { User user = repository.findById(id).orElseThrow(() -> { return new ResponseStatusException(NOT_FOUND, "User not found"); }); return ResponseEntity .ok(new UserResponse(user)); } }

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Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados GET /api/users/42

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Aplicação Usuário Banco de dados GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 SELECT u.* FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 HTTP 503 (SERVICE UNAVAILABLE) SELECT u.* FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 HTTP 503 (SERVICE UNAVAILABLE) SELECT u.* FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 HTTP 503 (SERVICE UNAVAILABLE) GET /api/users/42 SELECT u.* FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 HTTP 503 (SERVICE UNAVAILABLE) GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 SELECT u.* FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 HTTP 503 (SERVICE UNAVAILABLE) GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 SELECT u.* FROM user u WHERE ud.id = 42

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Aplicação Usuário Banco de dados GET /api/users/42 HTTP 503 (SERVICE UNAVAILABLE) GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 HTTP 200 (OK) SELECT u.* FROM user u WHERE ud.id = 42

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Mais do que isso…

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Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados GET /api/users/42

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Aplicação Usuário Banco de dados GET /api/users/42 SELECT u.* FROM user u WHERE ud.id = 42 5xx

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Aplicação Usuário Banco de dados GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 SELECT u.* FROM user u WHERE ud.id = 42 GET /api/users/42 GET /api/users/42 5xx

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Aplicação Usuário Banco de dados GET /api/users/42 GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 SELECT u.* FROM user u WHERE ud.id = 42 GET /api/users/42 GET /api/users/42 GET /api/users/42 5xx

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Aplicação Usuário Banco de dados GET /api/users/42 GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 SELECT u.* FROM user u WHERE ud.id = 42 GET /api/users/42 GET /api/users/42 GET /api/users/42 GET /api/users/42 . . . 5xx

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Aplicação Usuário Banco de dados GET /api/users/42 5xx GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 2xx SELECT u.* FROM user u WHERE ud.id = 42 GET /api/users/42 GET /api/users/42 GET /api/users/42 GET /api/users/42 . . .

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Aplicação Usuário Banco de dados GET /api/users/42 5xx GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 2xx SELECT u.* FROM user u WHERE ud.id = 42 GET /api/users/42 GET /api/users/42 GET /api/users/42 GET /api/users/42 . . . Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados GET /api/users/42 5xx GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 2xx SELECT u.* FROM user u WHERE ud.id = 42 GET /api/users/42 GET /api/users/42 GET /api/users/42 GET /api/users/42 . . . 2xx GET /api/users/42 Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados GET /api/users/42 5xx GET /api/users/42 SELECT 1 FROM user u WHERE ud.id = 42 2xx SELECT u.* FROM user u WHERE ud.id = 42 GET /api/users/42 GET /api/users/42 GET /api/users/42 GET /api/users/42 . . . ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com ... ... ... user Aplicação Usuário Banco de dados

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IDEMPOTENCY

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FUNCIONA MUITO BEM PARA ENDPOINTS DE LEITURA

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FUNCIONA MUITO BEM PARA ENDPOINTS DE LEITURA …mas não tão bem para endpoints de escrita

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IDEMPOTENCY O que acontece quando o cliente re-tenta uma requisição?

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IDEMPOTENCY O que acontece quando o cliente re-tenta uma requisição? …de ESCRITA

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action);

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Aplicação Usuário Banco de dados Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Banco de dados

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Aplicação Usuário Banco de dados Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Banco de dados 👀

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Aplicação Usuário Banco de dados INSERT INTO user (name , email) VALUES (:name, :email); POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } INSERT INTO user (name , email) VALUES (:name, :email); INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Network INSERT INTO user_audit (used_id, action) VALUES (:user_id, :action); Aplicação Usuário ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com 43 Gleice Elen gleice@gmail.com ... ... ... user 😱 Banco de dados

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TEMOS UM DUPLICIDADE BUG

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } } Nosso endpoint NÃO é idempotente! 😰

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https://opensource.zalando.com/restful-api-guidelines/#229 Zalando API Guidelines

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https://opensource.zalando.com/restful-api-guidelines/#229 Idempotency Key Zalando API Guidelines

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https://opensource.zalando.com/restful-api-guidelines/#229 Conditional Key Zalando API Guidelines

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https://opensource.zalando.com/restful-api-guidelines/#229 Secondary Key Zalando API Guidelines

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https://opensource.zalando.com/restful-api-guidelines/#229 Secondary Key Zalando API Guidelines

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@Entity public class User { @Id @GeneratedValue private Long id; private String name; private String email; private LocalDateTime createdAt; // construtor, getters etc }

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@Entity public class User { @Id @GeneratedValue private Long id; private String name; private String email; private LocalDateTime createdAt; // construtor, getters etc }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { throw new ResponseStatusException(BAD_REQUEST, "User exists”); // http 400 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { throw new ResponseStatusException(BAD_REQUEST, "User exists”); // http 400 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { throw new ResponseStatusException(BAD_REQUEST, "User exists”); // http 400 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } } 🥳 Email como chave natural de idempotência!

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SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email );

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { throw new ResponseStatusException(BAD_REQUEST, "User exists”); // http 400 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { throw new ResponseStatusException(BAD_REQUEST, "User exists”); // http 400 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } } 😵💫 Not cool!

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { throw new ResponseStatusException(BAD_REQUEST, "User exists”); // http 400 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } } 😍 Oh yeah!

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Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… Network

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… Network

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… Network POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… Network POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email );

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… Network POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email );

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); Network INSERT user_audit_… SELECT exists…

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); Network INSERT user_audit_… SELECT exists… Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); Network INSERT user_audit_… SELECT exists… Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); Network INSERT user_audit_… SELECT exists… Aplicação Usuário Banco de dados INSERT user… INSERT user_audit_… SELECT exists…

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); Network INSERT user_audit_… SELECT exists… Aplicação Usuário Banco de dados INSERT user… INSERT user_audit_… SELECT exists… SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); 💪

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); Network INSERT user_audit_… SELECT exists… Aplicação Usuário Banco de dados ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com ... ... ... user 🥳

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E se…

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Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email );

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email );

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx Aplicação Usuário Banco de dados SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx Aplicação Usuário Banco de dados SELECT exists… INSERT user… INSERT user_audit_… SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email );

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx Aplicação Usuário Banco de dados ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com ... ... ... user

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx Aplicação Usuário Banco de dados ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com ... ... ... user ID ACTION USER_ID ... ... ... ?? ?? ?? ... ... ... user_audit

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Aplicação Usuário Banco de dados INSERT user… POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists ( SELECT 1 FROM user u WHERE u.email = :email ); INSERT user_audit_… SELECT exists… 5xx Aplicação Usuário Banco de dados ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com ... ... ... user ID ACTION USER_ID ... ... ... ?? ?? ?? ... ... ... user_audit 😱

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TEMOS UM INCONSISTÊNCIA BUG

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); // inicia e comita uma transação UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); // inicia e comita uma transação return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); // inicia e comita uma transação UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); // inicia e comita uma transação return ResponseEntity .status(CREATED).build(); // http 201 } } Semelhante a auto_commit = true 😱

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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Para resolver…

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @Transactional @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @Transactional @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @Transactional @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 2xx Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 2xx Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } 2xx

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 2xx Aplicação Usuário Banco de dados SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 5xx POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } SELECT exists… INSERT user… INSERT user_audit_… 2xx Aplicação Usuário Banco de dados ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com ... ... ... user ID ACTION USER_ID ... ... ... 1024 created 42 ... ... ... user_audit 💪

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E se…

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Aplicação Usuário 1 Usuário 2

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Aplicação Usuário 1 Usuário 2 POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 HTTP 201 (CREATED) POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 HTTP 201 (CREATED) HTTP 201 (CREATED) POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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SELECT u.* FROM user u

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ID NAME EMAIL ... ... ... 42 Gleice Elen gleice@gmail.com 43 Gleice Elen gleice@gmail.com ... ... ... user 😱

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TEMOS UM RACE CONDITION BUG

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @Transactional @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @Transactional @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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@RestController public class CreateNewUserController { private UserRepository repository; private UserAuditRepository auditRepository; @Transactional @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { if (repository.existsByEmail(request.email())) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user); UserAudit audit = new UserAudit(user, "created"); auditRepository.save(audit); return ResponseEntity .status(CREATED).build(); // http 201 } }

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boolean exists = repository.existsByEmail(request.email()); if (exists) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user);

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boolean exists = repository.existsByEmail(request.email()); if (exists) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user);

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boolean exists = repository.existsByEmail(request.email()); if (exists) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user);

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boolean exists = repository.existsByEmail(request.email()); if (exists) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user);

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boolean exists = repository.existsByEmail(request.email()); if (exists) { return ResponseEntity.ok("User exists”); // http 200 }; User user = request.toModel(); repository.save(user);

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READ-MODIFY-WRITE

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READ-MODIFY-WRITE

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READ-MODIFY-WRITE

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READ-MODIFY-WRITE

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READ-MODIFY-WRITE ANTI-PATTERN

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@Entity public class User { @Id @GeneratedValue private Long id; private String name; private String email; private LocalDateTime createdAt; // construtor, getters etc }

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@Entity public class User { @Id @GeneratedValue private Long id; private String name; private String email; private LocalDateTime createdAt; // construtor, getters etc }

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@Entity public class User { @Id @GeneratedValue private Long id; private String name; @Column(unique = true) private String email; private LocalDateTime createdAt; // construtor, getters etc }

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ALTER TABLE user ADD CONSTRAINT uk_email UNIQUE (email);

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Ou podemos aumentar o nível de isolamento da transação…

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@Transactional( )

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@Transactional( isolation = Isolation.SERIALIZABLE )

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Aplicação Usuário 1 Usuário 2

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Aplicação Usuário 1 Usuário 2 POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 HTTP 201 (CREATED) POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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Aplicação Usuário 1 Usuário 2 HTTP 201 (CREATED) HTTP 409 (CONFLICT) POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” } POST /api/users { name: “Gleice Elen”, email: “gleice@gmail.com” }

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No content

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Você percebeu?

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Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados POST /api/users

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK

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Aplicação Usuário Banco de dados POST /api/users 2xx OK SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_…

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… ERROR

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… 5xx ERROR

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TUDO NADA ou

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TUDO ou NADA

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TUDO NADA ou

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Espera… onde já vimos isso? 🤔

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK 2xx Aplicação Usuário Banco de dados

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK 2xx Aplicação Usuário Banco de dados OK SELECT exists… INSERT user… INSERT user_audit_… Unit of Work

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK 2xx Aplicação Usuário Banco de dados POST /api/users 2xx

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK 2xx Aplicação Usuário Banco de dados 2xx POST /api/users Unit of Work

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK 2xx Aplicação Usuário Banco de dados OK SELECT exists… INSERT user… INSERT user_audit_… 2xx POST /api/users Unit of Work Unit of Work

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK 2xx Aplicação Usuário Banco de dados OK SELECT exists… INSERT user… INSERT user_audit_… 2xx POST /api/users Unit of Work Unit of Work

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Aplicação Usuário Banco de dados POST /api/users SELECT exists… INSERT user… INSERT user_audit_… OK 2xx Usuário Banco de dados OK SELECT exists… INSERT user… INSERT user_audit_… POST /api/users 2xx Unit of Work

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THE 1:1 MODEL Mapear uma transação para um HTTP request

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THE 1:1 MODEL Brandur | @brandur Mapear uma transação para um HTTP request

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https://brandur.org/http-transactions

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@RestController public class CreateNewUserController { private UserRepository repository; @Transactional @PostMapping(“/api/users") public ResponseEntity> create(@Valid @RequestBody NewUserRequest request) { // lógica de negócio return ResponseEntity .status(OK).build(); // http 200 } }

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CONCLUINDO

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Sistemas distribuídos podem ser difíceis… 😬

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No content

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“Use o banco apenas como repositório de dados.”

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“Use o banco apenas como repositório de dados.” Não!

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Recapitulando…

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Agora temos uma API REST que…

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No content

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…falha rapidamente

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…permite re-tentativas do cliente …falha rapidamente

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…abraça o tudo ou nada …permite re-tentativas do cliente …falha rapidamente

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…abraça o tudo ou nada …permite re-tentativas do cliente …falha rapidamente …previne falhas de races conditions

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No content

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Mas que serve para outras plataformas

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@rponte Rafael Ponte Obrigado!!