Microserviços em Kotlin com Dropwizard Felipe Lima Kotlin Meetup São Paulo 25 de Junho de 2020 felipecsl.com @felipecsl 

Introdução 

Um pouco de história… 

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Dropwizard 

Dropwizard @ Airbnb 

Fonte: website oficial - dropwizard.io “Dropwizard is a Java framework for developing ops-friendly, high- performance, RESTful web services.” 

“Elefante na sala" 

“Tá, mas por que diabos eu deveria usar Dropwizard ao invés de ” 

Fonte: https://blog.overops.com/java-bootstrap-dropwizard-vs-spring-boot Dropwizard vs. Spring Boot 

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Meu favorito 

• Criado em 2011 no Yammer • Arquitetura modular • Foco em produtividade, “get things done” • Java centric • Utiliza Jersey e Jetty Características 

Modularidade https://modules.dropwizard.io/official/ 

Simplicidade companion object { @Throws(Exception::class) @JvmStatic fun main(args: Array) { BrokerApplication().run(*args) } } 

Simplicidade class BrokerApplication : Application() { override fun initialize(bootstrap: Bootstrap) { bootstrap.apply { addBundle(webSocketBundle) addBundle(SslReloadBundle()) addBundle(RedirectBundle(HttpsRedirect())) } } override fun run(configuration: BrokerConfiguration, environment: Environment) { userDao = DaoFactory(environment, configuration).newDao(UserDao::class.java) sessionManager = SessionManagerFactory.newInstance( userDao, objectMapper, configuration ) environment.jersey().register(StatusResource(sessionManager)) environment.healthChecks().register("template", BrokerHealthCheck()) environment.jersey().register(UsersResource(userDao, sessionManager)) } 

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REST "Eclipse Jersey is a REST framework that provides a JAX-RS (JSR-370) implementation” https://eclipse-ee4j.github.io/jersey/ 

REST https://github.com/jax-rs/spec/blob/master/spec.pdf 

REST @Path("/status") @Produces(MediaType.APPLICATION_JSON) class StatusResource(private val sessionManager: SessionManager) { @GET @Timed fun healthStatus(): HealthStatus { return HealthStatus(sessionManager.totalActiveSessions()) } } 

REST @Path("/users") @Produces(MediaType.APPLICATION_JSON) class UsersResource( private val userDao: UserDao, private val sessionManager: SessionManager ) { @POST @Timed @Consumes(MediaType.APPLICATION_JSON) fun create(user: User): Response { userDao.insert(user) return Response.ok().build() } @PUT @Timed @Consumes(MediaType.APPLICATION_JSON) fun update(user: User): Response { userDao.updateUserIdByFcmToken(user) return Response.ok().build() } } 

Configurações • Único arquivo YAML • Passado por parâmetro para o server via linha de comando • Pode ser utilizado para centralizar todas as configurações do servidor 

Configurações // build.gradle run { args 'server', 'src/dist/config/broker.dev.yml' } 

Configurações database: driverClass: org.postgresql.Driver user: felipecsl password: url: jdbc:postgresql://localhost/clairvoyance_dev properties: charSet: UTF-8 # the maximum amount of time to wait on an empty pool before throwing an exception maxWaitForConnection: 1s # the SQL query to run when validating a connection's liveness validationQuery: "/* MyService Health Check */ SELECT 1" # the minimum number of connections to keep open minSize: 8 logValidationErrors: true # the maximum number of connections to keep open maxSize: 32 # whether or not idle connections should be validated checkConnectionWhileIdle: false # the amount of time to sleep between runs of the idle connection validation, abandoned cleaner and idle pool resizing evictionInterval: 10s # the minimum amount of time an connection must sit idle in the pool before it is eligible for eviction minIdleTime: 1 minute server: applicationContextPath: / applicationConnectors: - type: http port: 8080 

Configurações class BrokerApplication : Application() { // ... } 

Configurações class BrokerConfiguration : Configuration() { @JsonProperty var fcmCredentialJsonPath: String? = null @JsonProperty var iceConfigFilePath: String? = null @JsonProperty var database: DataSourceFactory = DataSourceFactory() } 

Database implementation "io.dropwizard:dropwizard-jdbi3:$dropwizardVersion" 

Database @RegisterRowMapper(UserMapper::class) interface UserDao { @SqlQuery("SELECT * FROM users") fun all(): List @SqlQuery("SELECT * FROM users WHERE user_id = :user_id") fun findByUserId(@Bind("user_id") userId: String): User? @SqlUpdate("UPDATE users SET user_id = :user_id, fcm_token = :fcm_token WHERE ID = :id") fun updateById(@BindBean user: User): Int @SqlUpdate("INSERT INTO users (user_id, fcm_token) VALUES (:user_id, :fcm_token)") fun insert(@BindBean user: User): Int @SqlUpdate("DELETE FROM users") fun deleteAll(): Int } 

Database Migrations // build.gradle plugins { id "org.flywaydb.flyway" version "6.4.0" } flyway { url = 'jdbc:h2:file:./clairvoyance_test' user = ‘fulano_de_tal’ } 

Database Migrations private fun initFlyway(configuration: BrokerConfiguration) { val database = configuration.database Flyway.configure() .dataSource(database.url, database.user, database.password) .load() .migrate() } 

Database Migrations 

Frontend • Freemarker • Mustache 

Testing testImplementation "io.dropwizard:dropwizard-testing:$dropwizardVersion" 

Testing @ExtendWith(DropwizardExtensionsSupport::class) class BrokerApplicationTest { private val client = OkHttpClient.Builder().build() private val localPort = DROPWIZARD.localPort @Test fun status() { val client = JerseyClientBuilder().build() val result = client .target(“http://localhost:$localPort/status") .request() .get(String::class.java) assertThat(result).isEqualTo("""{"activeSessions":0}""") } companion object { private val DROPWIZARD = DropwizardAppExtension( BrokerApplication::class.java, ResourceHelpers.resourceFilePath("broker.yml") ) } } 

Perguntas? 

Obrigado!