Events in Spring Boot - events

Is it possible to use events in Spring Boot? I need to execute one method but without waiting for return. I'm trying to use this:
public class GerarSeloEvent extends ApplicationEvent {
private TbPedido pedido;
private Integer cdCartorio;
public GerarSeloEvent(Object source, TbPedido pedido, Integer cdCartorio) {
super(source);
this.pedido = pedido;
this.cdCartorio = cdCartorio;
}
public TbPedido getPedido() {
return pedido;
}
public Integer getCdCartorio() {
return cdCartorio;
}
}
#Component
public class GerarSeloListener implements ApplicationListener<GerarSeloEvent> {
#Autowired
SeloService seloService;
#Override
public void onApplicationEvent(GerarSeloEvent event) {
seloService.gerarSelos(event.getPedido(), event.getCdCartorio());
}
}
and my call
GerarSeloEvent gerarSelos = new GerarSeloEvent(this, pedido, cdCartorio);
EnviarEmailPedidoEvent enviarEmail = new EnviarEmailPedidoEvent(this, pedido);
publisher.publishEvent(gerarSelos);
But my code waits to return anything to my front-end. I need one async event.

This should work:
#Component
public class GerarSeloListener {
private final SeloService seloService;
#Autowired
public GerarSeloListener(SeloService seloService) { ... }
#EventListener
#Async
public void handleGerarSeloEvent(GerarSeloEvent event event) {
....
}
You need to add #EnableAsync on one of your configuration (the best place is your #SpringBootApplication annotated class). But as Martin already said you don't need event if you want to process a method asynchronously: only add #Async and invoke it the usual way.
You may want to read the documentation

Related

Spring Boot with javax Event

I try to get spring boot working with cdi events.
I have the following class which fires the event.
#Component
#UIScope
public class Login extends LoginOverlay
{
#Autowired
private UserInfo userInfo;
#Inject
private Event<UpdateCWViewEvent> cwevent;
#PostConstruct
public void init()
{
addLoginListener(new ComponentEventListener<LoginEvent>()
{
#Override
public void onComponentEvent(LoginEvent event)
{
userInfo.login(event.getUsername(), event.getPassword());
if (userInfo.isLoggedIn())
{
setButtonLabel();
close();
cwevent.fire(new UpdateCWViewEvent());
}
}
});
}
}
And in another class the following method
public void update(#Observes(notifyObserver=Reception.IF_EXISTS) UpdateCWViewEvent event)
{
//do something
}
Now I have the following problem. I need an Implementation of javax.enterprise.event.Event. I tried to take weld and use the standard Eventimpl. Now, I tried to configure a Spring Configuration class to tell my application, there is an implementation of my event.
#Configuration
public class Config
{
#Bean
public Event<UpdateCWViewEvent> cwEvent()
{
//return EventImpl.of(injectionPoint, beanManagerImpl);
}
}
I dont know what to do with the injectionPoint and beanManagerImpl. Does anybody of you had the same problem and solved it? Or does anybody have an alternative to fire easy cdi events in a spring boot application?
Thank you very much and stay healthy!

Pipeline design pattern implementation using Spring Boot

Can someone guide me as how to implement the Pipeline design pattern using Spring Boot?
I understand that each Pipe step has to be implemented as a #Service. I would like to know if #Ordered can be added to have the steps executed without explicitly wiring the individual #Service classes as the number of pipes in my case could exceed 10.
You can have something like that:
public interface Pipe{
void chain(Message input, Pipeline pipeline);
}
public class abstract AbstractPipe implements Pipe {
public void chain(Message input, Pipeline pipeline){
try {
//Business process of pipe1 (i.e. process the message and return response (Result of processing))
Response response = processMessage(input);
//Sucessful while processing
Message output = onSuccess(response, input);
pipeline.next(output);
}catch(Exception exception){
//Failure while processing
onError(exception, input);
//Maybe, we can continue
//with an alternative message
}
}
public abstract Message onSuccess(Response response, Message originalMessage);
public abstract void onError(Throwable error, Message input);
public abstract Response processMessage(Message input);
}
#Service
public class Pipe1 extends AbstractPipe {
// Implementation of abstract methods
}
#Service
public class Pipe2 extends AbstractPipe {
// Implementation of abstract methods
}
#Service
public class Pipe3 extends AbstractPipe {
// Implementation of abstract methods
}
public interface Message {
public Object get(String key);
}
public class MessageImpl implements Message {
private final Map<String, Object> index;
public MessageImpl(){...}
public void set(String key, Objetc value){...}
public Object get(String key){...}
}
The Pipeline is a chain of Pipes. Each pipe executes a command and tell the pipeline to continue with a new message.
I'm not sure that Spring has an annotation called #Ordered. Maybe you mean #Order which :
defines the sort order for an annotated component.
I'm not sure that it can add something to the Pipeline implementation.
Hope that helps.

Wny am I getting "java.lang.IllegalStateException: No TransactionalEventListener annotation"?

I'm using Spring 4.3.8.RELEASE with Hibernate 5.1.5.Final. I want to have a method executed after another another transaction completes. That transaction is defined below
#Service("organizationService")
#Transactional
public class OrganizationServiceImpl implements OrganizationService, ApplicationEventPublisherAware
{
private ApplicationEventPublisher publisher;
#Override
public void setApplicationEventPublisher(ApplicationEventPublisher publisher)
{
this.publisher = publisher;
}
#Override
public void save(Organization organization)
{
...
// sync data with ThirdParty but only if something has definitelychanged on the SB
// side, in which case we want to send ThirdParty an update.
if (!hasSameAttributes)
{
publisher.publishEvent(new ThirdPartyOrganizationEvent(organization.getId()));
} // if
} // save
So here is the method that I want executed after the above transaction completes ...
#Service
public class ThirdPartyAPIServiceImpl implements ThirdPartyAPIService
{
#Override
#TransactionalEventListener
public boolean updateOrg(final ThirdPartyOrganizationEvent thirdPartyOrgEvent)
{
...
}
But when I load my application context I get this error
Caused by: java.lang.IllegalStateException: No TransactionalEventListener annotation found on method: public abstract boolean org.mainco.subco.myproject.service.ThirdPartyAPIService.updateOrg(org.mainco.subco.myproject.domain.ThirdPartyOrganizationEvent)
at org.springframework.transaction.event.ApplicationListenerMethodTransactionalAdapter.<init>(ApplicationListenerMethodTransactionalAdapter.java:55)
at org.springframework.transaction.event.TransactionalEventListenerFactory.createApplicationListener(TransactionalEventListenerFactory.java:55)
at org.springframework.context.event.EventListenerMethodProcessor.processBean(EventListenerMethodProcessor.java:159)
at org.springframework.context.event.EventListenerMethodProcessor.afterSingletonsInstantiated(EventListenerMethodProcessor.java:104)
... 34 more
Wbat do I need to do to get this configured properly?
Defining #TransactionalEventListener on interface method rather then on method implementing interface worked for me.

Accessing Beans outside of the Step Scope in Spring Batch

Is it possible to access beans defined outside of the step scope? For example, if I define a strategy "strategyA" and pass it in the job parameters I would like the #Value to resolve to the strategyA bean. Is this possible? I am currently working round the problem by getting the bean manually from the applicationContext.
#Bean
#StepScope
public Tasklet myTasklet(
#Value("#{jobParameters['strategy']}") MyCustomClass myCustomStrategy)
MyTasklet myTasklet= new yTasklet();
myTasklet.setStrategy(myCustomStrategy);
return myTasklet;
}
I would like to have the ability to add more strategies without having to modify the code.
The sort answer is yes. This is more general spring/design pattern issue rater then Spring Batch.
The Spring Batch tricky parts are the configuration and understanding scope of bean creation.
Let’s assume all your Strategies implement Strategy interface that looks like:
interface Strategy {
int execute(int a, int b);
};
Every strategy should implements Strategy and use #Component annotation to allow automatic discovery of new Strategy. Make sure all new strategy will placed under the correct package so component scan will find them.
For example:
#Component
public class StrategyA implements Strategy {
#Override
public int execute(int a, int b) {
return a+b;
}
}
The above are singletons and will be created on the application context initialization.
This stage is too early to use #Value("#{jobParameters['strategy']}") as JobParameter wasn't created yet.
So I suggest a locator bean that will be used later when myTasklet is created (Step Scope).
StrategyLocator class:
public class StrategyLocator {
private Map<String, ? extends Strategy> strategyMap;
public Strategy lookup(String strategy) {
return strategyMap.get(strategy);
}
public void setStrategyMap(Map<String, ? extends Strategy> strategyMap) {
this.strategyMap = strategyMap;
}
}
Configuration will look like:
#Bean
#StepScope
public MyTaskelt myTasklet () {
MyTaskelt myTasklet = new MyTaskelt();
//set the strategyLocator
myTasklet.setStrategyLocator(strategyLocator());
return myTasklet;
}
#Bean
protected StrategyLocator strategyLocator(){
return = new StrategyLocator();
}
To initialize StrategyLocator we need to make sure all strategy were already created. So the best approach would be to use ApplicationListener on ContextRefreshedEvent event (warning in this example strategy names start with lower case letter, changing this is easy...).
#Component
public class PlugableStrategyMapper implements ApplicationListener<ContextRefreshedEvent> {
#Autowired
private StrategyLocator strategyLocator;
#Override
public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
ApplicationContext applicationContext = contextRefreshedEvent.getApplicationContext();
Map<String, Strategy> beansOfTypeStrategy = applicationContext.getBeansOfType(Strategy.class);
strategyLocator.setStrategyMap(beansOfTypeStrategy);
}
}
The tasklet will hold a field of type String that will be injected with Strategy enum String using #Value and will be resolved using the locator using a "before step" Listener.
public class MyTaskelt implements Tasklet,StepExecutionListener {
#Value("#{jobParameters['strategy']}")
private String strategyName;
private Strategy strategy;
private StrategyLocator strategyLocator;
#BeforeStep
public void beforeStep(StepExecution stepExecution) {
strategy = strategyLocator.lookup(strategyName);
}
#Override
public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception {
int executeStrategyResult = strategy.execute(1, 2);
}
public void setStrategyLocator(StrategyLocator strategyLocator) {
this.strategyLocator = strategyLocator;
}
}
To attach the listener to the taskelt you need to set it in your step configuration:
#Bean
protected Step myTaskletstep() throws MalformedURLException {
return steps.get("myTaskletstep")
.transactionManager(transactionManager())
.tasklet(deleteFileTaskelt())
.listener(deleteFileTaskelt())
.build();
}
jobParameters is holding just a String object and not the real object (and I think is not a good pratice store a bean definition into parameters).
I'll move in this way:
#Bean
#StepScope
class MyStategyHolder {
private MyCustomClass myStrategy;
// Add get/set
#BeforeJob
void beforeJob(JobExecution jobExecution) {
myStrategy = (Bind the right strategy using job parameter value);
}
}
and register MyStategyHolder as listener.
In your tasklet use #Value("#{MyStategyHolder.myStrategy}") or access MyStategyHolder instance and perform a getMyStrategy().

AOP Spring Before Advice not working

The method DefaultProduitGeneriqueService.valider is not catched by the method traceWhenReturnedValueDoesntExistOrNotNecessary and I don't understand why?
package fr.generali.nova.atp.service.metier.impl;
public class DefaultProduitGeneriqueService extends DefaultService implements IProduitGeneriqueService, IBacAware {
...
#Override
#Traceable(value = ETraceableMessages.VALIDATION_PRODUIT_GENERIQUE, hasReturnedValue=Traceable.HAS_NOT_RETURNS_VALUE)
public void valider(ElementNiveauUn element) {
...
}
...
}
package fr.generali.nova.atp.logging.advisor;
#Aspect
public class TraceableAdvisor {
#Before(value = "execution(* fr.generali.nova.atp.service.metier.impl.*.*(..)) && #annotation(traceable) && args(element)", argNames = "element,traceable")
public void traceWhenReturnedValueDoesntExistOrNotNecessary(ElementNiveauUn element, Traceable traceable) {
...
}
}
Assuming that the service interfaces are in package fr.generali.nova.atp.service.metier.api:
package fr.generali.nova.atp.service.metier.api;
public interface IProduitGeneriqueService {
void valider(ElementNiveauUn element);
}
And the service implementations are in package fr.generali.nova.atp.service.metier.impl:
package fr.generali.nova.atp.service.metier.impl;
public class DefaultProduitGeneriqueServiceImpl implements IProduitGeneriqueService {
#Override
#Traceable(value = ETraceableMessages.VALIDATION_PRODUIT_GENERIQUE, hasReturnedValue=Traceable.HAS_NOT_RETURNS_VALUE)
public void valider(ElementNiveauUn element) {
// TODO: implement
}
}
Your aspect should look like this:
package fr.generali.nova.atp.logging.advisor;
#Aspect
public class TraceableAdvisor {
#Before(value = "execution(* fr.generali.nova.atp.service.metier.api.*.*(..)) && #annotation(traceable) && args(element)", argNames = "element,traceable")
public void traceWhenReturnedValueDoesntExistOrNotNecessary(ElementNiveauUn element, Traceable traceable) {
// TODO: implement
System.err.println("traced...");
}
}
The default proxy strategy for Spring AOP is JDK interface-based proxies, so Your pointcut expression should match the interface method execution, not the implementation method execution, and Your poincut expression may match either interface mothod execution or implementation method execution.
And remember to include an AspectJAutoProxyCreator in your configuration using for example <aspectj-autoproxy /> tag.
And here is a simple test to prove everyting is working:
public class TraceableAdvisorTest {
#Configuration
public static class TestConfiguration {
#Bean
public IProduitGeneriqueService produitGeneriqueService() {
return new DefaultProduitGeneriqueServiceImpl();
}
#Bean
public TraceableAdvisor traceableAdvisor() {
return new TraceableAdvisor();
}
#Bean
public AnnotationAwareAspectJAutoProxyCreator autoProxyCreator() {
return new AnnotationAwareAspectJAutoProxyCreator();
}
}
private AnnotationConfigApplicationContext testApplicationContext;
#Test
public void testTraceWhenReturnedValueDoesntExistOrNotNecessary() {
this.testApplicationContext = new AnnotationConfigApplicationContext();
this.testApplicationContext.register(TestConfiguration.class);
this.testApplicationContext.refresh();
IProduitGeneriqueService service = BeanFactoryUtils.beanOfType(this.testApplicationContext, IProduitGeneriqueService.class);
System.err.println("BEFORE");
service.valider(null);
System.err.println("AFTER");
}
}
The err output is:
BEFORE
traced...
AFTER
For all combinations:
fr.generali.nova.atp.service.metier.api.*.*(..)
fr.generali.nova.atp.service.metier.impl.*.*(..)
fr.generali.nova.atp.service.metier..*.*(..)
Make sure both beans are properly configured, either through annotations or in your appCtx.
It looks like your Aspect is definitely right, but how about the other class? Is it Spring enabled?
Also, if both classes are indeed configured correctly, are you sure that the instance being passed is a Spring bean and not a "new" instance from a constructor?

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