This Library provides an integration between AxonFramework and CDI specification from Java EE API version 8
Note that this is not official implementation. An official implementation provided by Axon team can be found among official public Axon GitHub repositories. The main idea of this Library is to have a bit more different approach in configuration and to provide more convenient tools specific for Java EE world
The Library requires Java EE container
dependencies {
implementation("com.scalified:axonframework-cdi:$VERSION")
}Each $VERSION consists of AxonFramework version and the Library version itself. For example, version
4.1.1-RELEASE indicates the AxonFramework version 4.1.1 and the Library version RELEASE
The following Axon components are available for injection out-of-the-box:
- org.axonframework.config.Configuration
- org.axonframework.commandhandling.gateway.CommandGateway
- org.axonframework.queryhandling.QueryGateway
- org.axonframework.modelling.command.Repository (specific for concrete Aggregate type)
Example:
// imports omitted
import org.axonframework.config.Configuration;
import org.axonframework.commandhandling.gateway.CommandGateway;
import org.axonframework.modelling.command.Repository;
import org.axonframework.queryhandling.QueryGateway;
@ApplicationScoped
public class SomeBean {
@Inject
private Configuration configuration;
@Inject
private CommandGateway commandGateway;
@Inject
private QueryGateway queryGateway;
@Inject
private Repository<Account> accountRepository;
@Inject
private Repository<Creditor> creditorRepository;
}Library provides the following lifecycle events:
- com.scalified.axonframework.cdi.event.AxonEvent (supertype)
- com.scalified.axonframework.cdi.event.AxonConfiguredEvent (fired once Axon configured)
- com.scalified.axonframework.cdi.event.AxonStartedEvent (fired once Axon started)
- com.scalified.axonframework.cdi.event.AxonStoppedEvent (fired once Axon stopped)
Events can be subscribed as follows:
// imports omitted
import org.axonframework.config.Configuration;
import com.scalified.axonframework.cdi.event.AxonEvent;
import com.scalified.axonframework.cdi.event.AxonConfiguredEvent;
import com.scalified.axonframework.cdi.event.AxonStartedEvent;
import com.scalified.axonframework.cdi.event.AxonStoppedEvent;
@ApplicationScoped
public class AxonEventListener {
void on(@Observes AxonEvent event) {
// ...
}
void on(@Observes AxonConfiguredEvent event) {
Configuration configuration = event.getConfiguration();
// ...
}
void on(@Observes AxonStartedEvent event) {
// ...
}
void on(@Observes AxonStoppedEvent event) {
// ...
}
}Axon library-specific properties can be provided as follows:
// imports omitted
import com.scalified.axonframework.cdi.AxonProperties;
@ApplicationScoped
public class AxonConfiguration {
AxonProperties axonProperties() {
return AxonProperties.builder()
.autoStartEnabled(false)
.build();
}
}Any Axon component (except Aggregates and Sagas), which is expected to be processed, must be annotated with
@AxonComponent annotation. This annotation can be put on either a type (class) or producer method (annotated
with @Produces). During startup, all components annotated with @AxonComponent annotation are collected and
applied on Axon configuration. For the known Axon components the specific configuration method will be
invoked (e.g. configureTransactionManager). For any other component the registerComponent(..) method
will be invoked. For example:
// imports omitted
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
import org.axonframework.common.transaction.TransactionManager;
import com.scalified.axonframework.cdi.configuration.transaction.JtaTransactionManager;
@ApplicationScoped
public class CdiSetup {
@Produces
@AxonComponent
TransactionManager transactionManager() {
return new JtaTransactionManager(); // configureTransactionManager(conf -> transactionManager);
}
@Produces
@AxonComponent
SomeBean someService() {
return new SomeBean(); // registerComponent(SomeBean.class, conf -> someBean);
}
}Alternatively, components can be provided using Configurable function. This function accepts Axon Configuration
object and returns the Axon component. This is extremely helpful for cases, when there is a need in Axon
Configuration for configuring the component or when, for example, there is no way to annotate an existing component
with @AxonComponent annotation (dependency etc.). The Configurable component can be either produced or declared:
// imports omitted
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
import com.scalified.axonframework.cdi.api.Configurable;
@ApplicationScoped
public class CdiSetup {
@Produces
@AxonComponent
Configurable<TokenStore> tokenStore(EntityManagerProvider provider) {
return configuration -> JpaTokenStore.builder()
.entityManagerProvider(provider)
.serializer(configuration.serializer())
.build();
}
}// imports omitted
import com.scalified.axonframework.cdi.api.Configurable;
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
@AxonComponent
public class CommandBusConfigurable implements Configurable<CommandBus> {
@Override
public CommandBus apply(Configuration configuration) {
return SimpleCommandBus.builder().build();
}
}Aggregates and Sagas have special annotations, which must be put on Aggregate or Saga type (class)
instead of @AxonComponent annotation. These are @Aggregate and @Saga respectively.
Aggregate configurations can be provided via AggregateConfigurator function, which accepts the Aggregate
type (class) and returns AggregateConfigurer instance. For providing specific Aggregate configurations, the
Aggregate type must be specified via @AxonComponent annotation's ref() method:
// imports omitted
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
import com.scalified.axonframework.cdi.api.AggregateConfigurator;
@ApplicationScoped
public class CdiSetup {
// Default AggregateConfigurator
@Produces
@AxonComponent
AggregateConfigurator defaultAggregateConfigurator() {
return type -> AggregateConfigurer.defaultConfiguration(type);
}
// AggregateConfigurator specific for Account Aggregate
@Produces
@AxonComponent(ref = Account.class)
AggregateConfigurator accountAggregateConfigurator() {
return type -> AggregateConfigurer.defaultConfiguration(type)
.configureRepository(conf -> EventSourcingRepository.builder(type)
.eventStore(conf.eventStore())
.build());
}
}The Aggregate itself must be annotated with @Aggregate annotation:
// imports omitted
import com.scalified.axonframework.cdi.api.annotation.Aggregate;
@Aggregate
public class Account {
@AggregateIdentifier
private String id;
private double balance;
public Account(OpenAccountCommand command) {
AccountOpenedEvent event = AccountOpenedEvent.builder()
.id(command.getId())
.balance(command.getBalance())
.build();
apply(event);
}
@EventSourcingHandler
public void on(AccountOpenedEvent event) {
this.id = event.getId();
this.balance = event.getBalance();
}
}Saga configurations can be provided via SagaConfigurator consumer, which accepts the SagaConfigurer instance
For providing specific Saga configurations, the Saga type must be specified via @AxonComponent
annotation's ref() method:
// imports omitted
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
import com.scalified.axonframework.cdi.api.SagaConfigurator;
@ApplicationScoped
public class CdiSetup {
// Default SagaConfigurator
@Produces
@AxonComponent
SagaConfigurator defaultSagaConfigurator(EntityManagerProvider provider) {
return configurer -> configurer.configureSagaStore(conf -> JpaSagaStore.builder()
.entityManagerProvider(provider)
.serializer(conf.serializer())
.build());
}
// SagaConfigurator specific for Account Saga
@Produces
@AxonComponent(ref = AccountSaga.class)
SagaConfigurator accountSagaConfigurator() {
return configurer -> configurer.configureSagaStore(conf -> JpaSagaStore.builder()
.entityManagerProvider(provider)
.serializer(XStreamSerializer.defaultSerializer())
.build());
}
}The Saga itself must be annotated with @Saga annotation:
// imports omitted
import com.scalified.axonframework.cdi.api.annotation.Saga;
@Saga
public class AccountSaga {
@StartSaga
@SagaEventHandler(associationProperty = "id")
private void on(AccountOpenedEvent event) {
// ...
}
}// imports omitted
@AxonComponent
public class AccountCommandHandler {
@Inject
private Repository<Account> repository;
@CommandHandler
public void handle(OpenAccountCommand command) throws Exception {
repository.newInstance(() -> new Account(command));
}
}// imports omitted
@AxonComponent
public class AccountEventHandler {
@EventHandler
public void on(AccountOpenedEvent event) {
// ...
}
}// imports omitted
@AxonComponent
public class AccountQueryHandler {
@QueryHandler
public void on(GetAccountBalanceQuery query) {
// ...
}
}Axon distinguishes default, message and event serializers. To provide different serializers, its type
must be specified via @AxonComponent annotation's value() method:
// imports omitted
import com.scalified.axonframework.cdi.api.SerializerType;
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
@ApplicationScoped
public class CdiSetup {
@Produces
@AxonComponent(SerializerType.DEFAULT)
Serializer serializer() {
return JacksonSerializer.defaultSerializer();
}
@Produces
@AxonComponent(SerializerType.MESSAGE)
Serializer messageSerializer() {
return JacksonSerializer.defaultSerializer();
}
@Produces
@AxonComponent(SerializerType.EVENT)
Serializer eventSerializer() {
return JacksonSerializer.defaultSerializer();
}
}Event processing can be further customized via EventProcessingConfigurator consumer, which accepts
EventProcessingConfigurer instance:
// imports omitted
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
import com.scalified.axonframework.cdi.api.EventProcessingConfigurator;
@ApplicationScoped
public class CdiSetup {
@Produces
@AxonComponent
EventProcessingConfigurator eventProcessingConfigurator(EntityManagerProvider provider) {
return configurer -> configurer.registerSagaStore(conf -> JpaSagaStore.builder()
.serializer(conf.serializer())
.entityManagerProvider(provider)
.build());
}
}MessageDispatchInterceptor for commands, which implements CommandDispatchInterceptor interface are registered
automatically:
// imports omitted
import com.scalified.axonframework.cdi.api.CommandDispatchInterceptor;
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
@AxonComponent
public class NoOpCommandDispatchInterceptor implements CommandDispatchInterceptor {
@Override
public BiFunction<Integer, CommandMessage<?>, CommandMessage<?>> handle(List<? extends CommandMessage<?>> messages) {
return (idx, message) -> message;
}
}MessageDispatchInterceptor for events, which implements EventDispatchInterceptor interface are registered
automatically:
// imports omitted
import com.scalified.axonframework.cdi.api.EventDispatchInterceptor;
import com.scalified.axonframework.cdi.api.annotation.AxonComponent;
@AxonComponent
public class NoOpEventDispatchInterceptor implements EventDispatchInterceptor {
@Override
public BiFunction<Integer, EventMessage<?>, EventMessage<?>> handle(List<? extends EventMessage<?>> messages) {
return (idx, message) -> message;
}
}Copyright 2019 Scalified
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.