kediatR

Mediator implementation in kotlin with native coroutine support.

Supports synchronous and async (using kotlin coroutines ) command and query handling, native kotlin implementation and spring-boot configuration

kediatR has two implementations: kediatR-core and kediatR-spring

kediatR-core

<dependency>
  <groupId>com.trendyol</groupId>
  <artifactId>kediatr-core</artifactId>
  <version>1.0.7-SNAPSHOT</version>
</dependency>

kediatR-spring-starter

<dependency>
  <groupId>com.trendyol</groupId>
  <artifactId>kediatr-spring-starter</artifactId>
  <version>1.0.8</version>
</dependency>

Usage

add kediatr-core dependency to your POM

Command dispatching

fun main(){
    // pass any class in package which contains handlers to CommandBusBuilder. 
    // So, kediatR may scans your package and registers command and query handlers 
    val bus: CommandBus = CommandBusBuilder(HelloCommand::class.java).build()
    bus.executeCommand(HelloCommand("hello"))
}

class HelloCommand(val message: String) : Command

class HelloCommandHandler: CommandHandler<HelloCommand>{
    override fun handle(command: MyCommand) {
        println(command.message)
    }
}

Query dispatching

fun main(){
    val bus: CommandBus = CommandBusBuilder(GetSomeDataQuery::class.java).build()
    val result: String = bus.executeQuery(GetSomeDataQuery(1))
    println(result)
}

class GetSomeDataQuery(val id: Int) : Query<String>

class GetSomeDataQueryHandler: QueryHandler<String, GetSomeDataQuery> {
    override fun handle(query: GetSomeDataQuery): String {
        // you can use properties in the query object to retrieve data from somewhere
        // val result = getDataFromSomewhere(query.id)
        // return result

        return "hello"
    }
}

Usage with Spring

add kediatr-spring dependency to your POM and enjoy yourself

@Service
class UserService(private val commandBus: CommandBus){
    fun findUser(id: Long){
        return commandBus.executeQuery(GetUserByIdQuery(id))
    }
}

class GetUserByIdQuery(private val id: Long): Query<UserDto>

@Component
class GetUserByIdQueryHandler(private val userRepository: UserRepository) : QueryHandler<UserDto, GetUserByIdQuery> {
    fun handle(query: GetUserByIdQuery): UserDto { 
        val user = userRepository.findById(query.id)
        // do some operation on user
        return UserDto(user.id, user.name, user.surname)
    }
}

Async Usage with Kotlin Coroutine Support

 
class UserService(private val commandBus: CommandBus ){
    suspend fun findUser(id: Long){
        return commandBus.executeQueryAsync(GetUserByIdQuery(id))
    }
}

class GetUserByIdQuery(private val id: Long): Query<UserDto>

class GetUserByIdQueryHandler(private val userRepository: UserRepository) : AsyncQueryHandler<UserDto, GetUserByIdQuery> {
    suspend fun handleAsync(query: GetUserByIdQuery): UserDto { 
        val user = userRepository.findByIdAsync(query.id)
        // do some operation on user
        return UserDto(user.id, user.name, user.surname)
    }
}

CanerPatir / kediatR