dependency cycle on spring WebSocket interceptor and spring cloud stream - spring-websocket

Question

i am trying to create a websocket interceptor that do send a message using MessageChannel from spring cloud stream . i am facing a dependency cycle
┌─────┐
| myChannelInterceptor defined in file [/Users/shahbour/IdeaProjects/proxy/target/classes/com/xxxxx/proxy/broker/MyChannelInterceptor.class]
↑ ↓
| com.xxxx.proxy.service.XxxxxBinding (field private java.util.Map org.springframework.cloud.stream.binding.BindableProxyFactory.bindingTargetFactories)
↑ ↓
| org.springframework.cloud.stream.config.BindingServiceConfiguration (field private java.util.List org.springframework.cloud.stream.config.BindingServiceConfiguration.customMessageConverters)
↑ ↓
| org.springframework.web.socket.config.annotation.DelegatingWebSocketMessageBrokerConfiguration
↑ ↓
| webSocketConfig defined in file [/Users/shahbour/IdeaProjects/proxy/target/classes/com/xxxx/proxy/config/WebSocketConfig.class]
└─────┘
My problem is that i need to inject a MessageChannel into the websocket interceptor
I am receiving the below error if i use #Autowire
org.springframework.context.ApplicationContextException: Failed to start bean 'subProtocolWebSocketHandler'; nested exception is java.lang.IllegalArgumentException: No handlers
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:167) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:50) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:348) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:151) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:114) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:879) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.finishRefresh(EmbeddedWebApplicationContext.java:144) ~[spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:545) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE]
at com.xxxx.proxy.xxxxxxProxyApplication.main(XxxxxProxyApplication.java:29) [classes/:na]
Caused by: java.lang.IllegalArgumentException: No handlers
at org.springframework.util.Assert.isTrue(Assert.java:92) ~[spring-core-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.web.socket.messaging.SubProtocolWebSocketHandler.start(SubProtocolWebSocketHandler.java:244) ~[spring-websocket-4.3.7.RELEASE.jar:4.3.7.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:175) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE]
... 15 common frames omitted

Answer 1

OK. Thank you! No I see the problem.
Look:
Your MyChannelInterceptor depends on the auto-created channel by the BinderService.
That one tries to infer MessageConverters from the application context.
The AbstractMessageBrokerConfiguration provides one in face of CompositeMessageConverter brokerMessageConverter
That class is instantiated by the #EnableWebSocketMessageBroker
which, in turn, scans your WebSocketConfig because of the AbstractWebSocketMessageBrokerConfigurer
And this last one wants your MyChannelInterceptor to be injected.
Not sure how to fix that as an out-of-the-box feature, but here is some kind of workaround:
public class MyChannelInterceptor extends ChannelInterceptorAdapter {
#Autowired
private MessageChannel output;
#Configuration
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
#Bean
public MyChannelInterceptor myChannelInterceptor() {
return new MyChannelInterceptor();
}
...
#Override
public void configureClientInboundChannel(ChannelRegistration registration) {
registration.setInterceptors(myChannelInterceptor());
}