Spring Boot Microservices Meetup

ACCENTURE
TECHNOLOGY
MEETUP
SPRING BOOT
BASED
MICROSERVICES

• Application as a suit of small services
• Services are split around business capability
• Lightweight
• smaller the better
• Services are independent
• Better testability
• Better deployability
• Improved fault isolation and tolerance
• Great agility and scalability
MICROSERVICES
Copyright © 2018 Accenture. All rights reserved. 2

• CRUD operations
• get, post, put, delete
• Should get all data needed
• Header
• URL (path, request parameters)
• Body (content type?)
MICROSERVICE BASICS

• Naming is consequent with function
• GET /meetup/team
• POST /meetup/team
– -> Location: /meetup/team/{id}
• GET /meetup/team/{id}
• PUT /meetup/team/{id}
• DELETE /meetup/team/{id}
SERVICE URLS

• Headers
• Accept
• Content-Type
• Authentication
• Accept-Language
• Location
• Allow-Origin
HEADERS

• 200 - OK
• 201 - Created
• 204 - No content
• 401 - Unauthorized
• 403 - Forbidden
• 404 - Not found
• 406 - Not acceptable
• 409 - Conflict
• 415 - Unsupported media type
• 422 - Unprocessable entity
RESPONSE CODES

• REST vs SOAP
• Data is provided as input, no state stored
• JSON vs html
• Calling external services
• Dependencies should be avoided
• Shared data between services
• Keep as low as possible
TO DO, OR NOT TO DO?

• data
• mvc
• web
• aop
• annotations
• boot
• cloud
SPRING FUNCTIONS

• Swiss army knife toolkit
• Stand-alone Spring application
• Runnable JAR file
• Tested for stability
• No dependency issues
• Runnable jar
• Embedded application server
• Gradle or Maven support
• Low overhead
SPRING BOOT - BASICS
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>

• @SpringBootApplication
• main()
APPLICATION
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}

• @RestController
• @RequestMapping
CONTROLLER ANNOTATION
@RestController
public class MeetupController {
@Autowired
private MeetupService meetupService;
@RequestMapping(value = "/person/{id}", method = RequestMethod.GET)
public Optional<Person> getPerson(HttpServletRequest httpServletRequest, @PathVariable("id") String id) {
return meetupService.getPerson(id);
}

• To handle HTTP OPTIONS call
• Implemented as filter
• Headers returned
• Access-Control-Allow-Methods
• Access-Control-Allow-Headers
• Access-Control-Allow-Origin
• Access-Control-Max-Age
• Access-Control-Allow-Credentials
CORS FILTER

• LoggingFilter
• HTTP Request and response
– Headers, URL and params
– doFilter
• ControllerLoggerAspect
• @Component
• @Aspect
• @Before({pointcut})
LOGGING ASPECTS
@Aspect
@Component
public class ControllerLoggerAspect {
@Before("execution(* com.accenture.meetup.controller.MeetupController.*(..))")
public void logBefore(JoinPoint joinPoint) {
}
}
}
@Component
public class LoggingFilter implements Filter {
@Override
public void doFilter(ServletRequest servletRequest,
ServletResponse servletResponse, FilterChain filterChain) {
}
}

• @ControllerAdvice
• implements RequestBodyAdvice
– boolean supports(...)
– beforeBodyRead(...)
– afterBodyRead(...)
– handleEmptyBody(...)
• implements ResponseBodyAdvice
– boolean supports(...)
– beforeBodyWrite(...)
REQUEST AND RESPONSE BODY
@ControllerAdvice
public class RequestBodyLogger implements RequestBodyAdvice {
@Override
public boolean supports(MethodParameter methodParameter,
Type targetType,
Class<? extends HttpMessageConverter<?>> converterType) {
}
@Override
public Object handleEmptyBody(Object body,
HttpInputMessage inputMessage, MethodParameter parameter,
Type targetType,
}
@Override
public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage,
MethodParameter parameter, Type targetType,
}
@Override
public Object afterBodyRead(Object body,
HttpInputMessage inputMessage, MethodParameter parameter,
Type targetType,
}
}

• Implemented as ControllerAdvice
• @ControllerAdvice
• Based on exception type
• @ExceptionHandler
• Sets HTTP error codes
• @ResponseStatus
ERROR HANDLER
@ControllerAdvice
public class GlobalExceptionHandler extends
ResponseEntityExceptionHandler {
@ExceptionHandler(NotFoundException.class)
@ResponseStatus(value = HttpStatus.NOT_FOUND)
public void handleNotFoundException(NotFoundException e) {
logger.error(e.getMessage());
}
}

• spring-data
• One for each entity
• @Repository
• extends CrudRepository(<T, ID>)
– save
– findById
– deleteById
DATABASE ACCESS
@Repository
public interface TeamRepository extends CrudRepository<Team, String> {
}

• Unit tests
• In memory database (h2)
• Mockito and mock mvc for controller - TDD
• Cucumber – BDD
• Sonar – quality gates
• PACT – contract
QUALITY CONTROL

• Uses real service
• Includes filters, aspects and error handlers
• @AutoConfigureMockMvc
• @SpringBootTest
• @RunWith(Springrunner.class)
• mvc.perform()
MOCK MVC
@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureMockMvc
public class MeetupControllerTest {
@Autowired
private MockMvc mvc;
@Test
public void getHealthcheck() throws Exception {
mvc.perform(MockMvcRequestBuilders.get("/healthcheck")
.accept(MediaType.APPLICATION_JSON))
.andExpect(status().isOk());
}
}

• Contract based interface verification
• Mock services and interactions
• DSM format
• pact-mock-server
• Can be generated
PACT
Contract
Partner A
e.g. CLIENT
Contract
Partner B
e.g. BACK
END
PACT

• Root interaction
• Options request
• Acceptance vs Compatibility
• Header and body matching
• Samples by value generators
• Json objects
PACT – BEST PRACTICES

• Describes Behaviour – BDD
• Human readable
• POs and BAs can also understand
– Given...
– When...
– Then...
• Scenarios and Scenariooutlines with examples
CUCUMBER

• Physical hardware
• chroot jail, selinux
• VMware, Hyper-V
• shared libs?
• docker (expendables)
• docker builder
• swarm (there's more)
DOCKER EVOLUTION

• perfect match
• easy to...
• integrate (jenkins, maven)
• deploy
• scale
• Can be automatically built
• maven, gradle etc.
• Can be automatically deployed
• CI, CD, jenkins, bamboo etc.
SPRINGBOOT AND DOCKER

• Health check
• spring-actuator
• Logging
• Monitoring
• Sizing (jvm, cpu)
CONSIDERATIONS

• microservice basics
• springboot
• cucumber
• pact
• docker
SUMMARY

THANK YOU
accenture.hu

Spring Boot Microservices Meetup

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