kcqrs

class Invoice private constructor(@JvmField var customerName: String, @JvmField val amount: BigDecimal) : AggregateRootBase() {

  // Required for the serialization 
  constructor() : this("", BigDecimal.ZERO)

  constructor(id: UUID, customerName: String, amount: BigDecimal) : this(customerName, amount) {
    applyChange(InvoiceCreatedEvent(id, customerName))
  }

  fun changeCustomerName(customerName: String) {
    applyChange(InvoiceCustomerNameChangedEvent(getId()!!, customerName))
  }

  fun apply(event: InvoiceCreatedEvent) {
    uuid = event.invoiceId
    customerName = event.customerName    
  }

  fun apply(event: InvoiceCustomerNameChangedEvent) {
    customerName = event.newCustomerName
  }
}
    
data class InvoiceCreatedEvent(@JvmField val invoiceId: UUID, @JvmField val customerName: String) : Event
    
data class InvoiceCustomerNameChangedEvent(@JvmField val invoiceId: UUID, @JvmField val newCustomerName: String) : Event

// ...
// Usage 
val invoice = Invoice(UUID.randomUUID(), "John", BigDecimal(30))        
eventRepository.save(invoice)

invoice.changeCustomerName("Peter")
eventRepository.save(invoice)

// Load Invoice document from events
val updateInvoice = eventRepository.getById(invoice.getId()!!, Invoice::class.java)

val messageBus = cqrs.messageBus()

// On App Initialization 
messageBus.registerCommandHandler(ChangeCustomerName::class.java, ChangeCustomerNameHandler())

// Dispatch User Action in Servlet or REST Api Call 
fun registerNewCustomer(req: HttpServletRequest, HttpServletResponse) {     
  msgBus.send(RegisterNewCustomer(req.getParameter("name")))      
} 

val messageBus = cqrs.messageBus()

// On App Initialization 
msgBus.registerEventHandler(CustomerRegisteredEvent::class.java, CustomerRegisteredEventHandler(InMemoryCustomerRepository()))

// Handle registration event      
msgBus.handle(CustomerRegisteredEvent("Any Customer Name"))       

val msgBus = cqrs.messageBus()
val pubSubPublisher = object : Interceptor {
   override fun intercept(chain: Interceptor.Chain) {     
     // make sure that event is processed by other handlers                                 
     chain.proceed(chain.event())
     
     val pubSubEvent = adapt(chain.event())     
     pubSubPublisher.publish(pubSubEvent)
  }
}
msgBus.registerInterceptor(pubSubPublisher)

// ....
msgBus.handle(event)                

class KCqrsEventHandler : AbstractEventHandlerServlet() {
    private val gson = Gson()

    override fun decode(inputStream: InputStream, type: Class<*>): Event {
        val event = gson.fromJson(InputStreamReader(inputStream, "UTF-8"), type)
        return event as Event
    }

    override fun messageBus(): MessageBus {
        return CQRSContext.messageBus()
    }
    
}

  <servlet>
    <servlet-name>kcqrsEventHandler</servlet-name>
    <servlet-class>com.clouway.kcqrs.example.KCqrsEventHandler</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>kcqrsEventHandler</servlet-name>
    <url-pattern>/worker/kcqrs</url-pattern>
  </servlet-mapping>

  <security-constraint>
    <web-resource-collection>
      <web-resource-name>worker</web-resource-name>
      <url-pattern>/worker/*</url-pattern>
    </web-resource-collection>
    <auth-constraint>
      <role-name>admin</role-name>
    </auth-constraint>
  </security-constraint>

// Initialize KCQRS for GAE
private var cqrs = AppEngineKcqrs.Builder(configuration, messageFormatFactory).build {
    kind = "Event"
    kcqrsHandlerEndpoint = "/worker/kcqrs"
    identityProvider = IdentityProvider.Default()
    requestInitializer = HttpRequestInitializer { 
        it.headers.setAuthorization("Bearer ${securityProvider.getAuthorizationToken()}")
    }
} 

// Accessing message bus
cqrs.messageBus()
// Accessing repository 
cqrs.repository()

    <dependency>
      <groupId>com.clouway.kcqrs</groupId>
      <artifactId>kcqrs-core</artifactId>
      <version>0.0.1</version>
    </dependency>
    
   <dependency>
      <groupId>com.clouway.kcqrs.adapters</groupId>
      <artifactId>kcqrs-appengine</artifactId>
      <version>0.0.1</version>
    </dependency>