How to Customize ServerRSocketFactory with Leases - spring

Question

I have written a simple RSocket server and client using Spring 5.2, Spring Boot 2.2.0M6 and Spring Cloud Hoxton.M2.
I am trying to customize the RSocket server's ServerRSocketFactory by adding the handling of leases according to the official RSocket sample.
I am using ServerRSocketFactoryCustomizer to add lease handling.
But when I declare the customizer bean and start the server, I receive exceptions from Spring-Cloud-Stream's FunctionConfiguration (version 3.0.0.M3) saying "Found more then one function in BeanFactory".
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'standAloneSupplierFlow' defined in class path resource [org/springframework/cloud/stream/function/FunctionConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.integration.dsl.IntegrationFlow]: Factory method 'standAloneSupplierFlow' threw exception; nested exception is java.lang.IllegalArgumentException: Found more then one function in BeanFactory
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:645) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:625) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1339) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1178) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:878) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-2.2.0.M6.jar:2.2.0.M6]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.0.M6.jar:2.2.0.M6]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.0.M6.jar:2.2.0.M6]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.0.M6.jar:2.2.0.M6]
at com.equalities.cloud.rsocket.server.RsocketServerApplication.main(RsocketServerApplication.java:19) ~[classes/:na]
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.integration.dsl.IntegrationFlow]: Factory method 'standAloneSupplierFlow' threw exception; nested exception is java.lang.IllegalArgumentException: Found more then one function in BeanFactory
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:640) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
... 17 common frames omitted
Caused by: java.lang.IllegalArgumentException: Found more then one function in BeanFactory
at org.springframework.util.Assert.isTrue(Assert.java:118) ~[spring-core-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.cloud.function.context.catalog.BeanFactoryAwareFunctionRegistry.discoverDefaultDefinitionIfNecessary(BeanFactoryAwareFunctionRegistry.java:194) ~[spring-cloud-function-context-3.0.0.M2.jar:3.0.0.M2]
at org.springframework.cloud.function.context.catalog.BeanFactoryAwareFunctionRegistry.compose(BeanFactoryAwareFunctionRegistry.java:212) ~[spring-cloud-function-context-3.0.0.M2.jar:3.0.0.M2]
at org.springframework.cloud.function.context.catalog.BeanFactoryAwareFunctionRegistry.lookup(BeanFactoryAwareFunctionRegistry.java:104) ~[spring-cloud-function-context-3.0.0.M2.jar:3.0.0.M2]
at org.springframework.cloud.function.context.FunctionCatalog.lookup(FunctionCatalog.java:72) ~[spring-cloud-function-context-3.0.0.M2.jar:3.0.0.M2]
at org.springframework.cloud.stream.function.FunctionConfiguration.standAloneSupplierFlow(FunctionConfiguration.java:90) ~[spring-cloud-stream-3.0.0.M3.jar:3.0.0.M3]
at org.springframework.cloud.stream.function.FunctionConfiguration$$EnhancerBySpringCGLIB$$f29b466d.CGLIB$standAloneSupplierFlow$1(<generated>) ~[spring-cloud-stream-3.0.0.M3.jar:3.0.0.M3]
at org.springframework.cloud.stream.function.FunctionConfiguration$$EnhancerBySpringCGLIB$$f29b466d$$FastClassBySpringCGLIB$$d3c910a8.invoke(<generated>) ~[spring-cloud-stream-3.0.0.M3.jar:3.0.0.M3]
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) ~[spring-context-5.2.0.RC2.jar:5.2.0.RC2]
at org.springframework.cloud.stream.function.FunctionConfiguration$$EnhancerBySpringCGLIB$$f29b466d.standAloneSupplierFlow(<generated>) ~[spring-cloud-stream-3.0.0.M3.jar:3.0.0.M3]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.0.RC2.jar:5.2.0.RC2]
... 18 common frames omitted
I am using the following code to declare the customizer:
#Bean
public ServerRSocketFactoryCustomizer leaseCustomizer() {
// Here, we return a ServerRSocketFactoryCustomizer bean to influence
// how the RSocket server is configured.
//
// A ServerRSocketFactory is defined by rsocket-java as an API that
// is used to create a server-side RSocket, using RSocketFactory.receive().
// Among other things, it is used to configure leases to clients as shown in this sample:
// https://github.com/rsocket/rsocket-java/blob/master/rsocket-examples/src/main/java/io/rsocket/examples/transport/tcp/lease/LeaseExample.java
//
// On the client side, a similar class, ClientRSocketFactory, exists.
// This can be customized using the RSocketRequester.Builder's .rsocketFactory() method.
// See: https://docs.spring.io/spring/docs/5.2.0.RELEASE/spring-framework-reference/web-reactive.html#rsocket-requester-client-advanced
// See: org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration
return new LeaseCustomizer();
}
where LeaseCustomizer looks as follows:
public class LeaseCustomizer implements ServerRSocketFactoryCustomizer {
#Override
public ServerRSocketFactory apply(ServerRSocketFactory factory) {
factory.lease(() -> Leases.<NoopStats>create()
.sender(new LeaseSender("Server", 7_000, 5))
.receiver(new LeaseReceiver("Server")));
return factory;
}
private static class NoopStats implements LeaseStats {
#Override
public void onEvent(EventType eventType) {}
}
#Slf4j
private static class LeaseSender implements Function<Optional<NoopStats>, Flux<Lease>> {
private final String tag;
private final int ttlMillis;
private final int allowedRequests;
public LeaseSender(String tag, int ttlMillis, int allowedRequests) {
this.tag = tag;
this.ttlMillis = ttlMillis;
this.allowedRequests = allowedRequests;
}
#Override
public Flux<Lease> apply(Optional<NoopStats> leaseStats) {
log.info("{} stats are {}", tag, leaseStats.isPresent() ? "present" : "absent");
return Flux.interval(ofSeconds(1), ofSeconds(10))
.onBackpressureLatest()
.map( tick -> {
log.info("{} responder sends new leases: ttl: {}, requests: {}", tag, ttlMillis, allowedRequests);
return Lease.create(ttlMillis, allowedRequests);
});
}
}
#Slf4j
private static class LeaseReceiver implements Consumer<Flux<Lease>> {
private final String tag;
public LeaseReceiver(String tag) {
this.tag = tag;
}
#Override
public void accept(Flux<Lease> receivedLeases) {
receivedLeases.subscribe(lease -> log.info("{} received leases - ttl: {}, requests: {}", tag, lease.getTimeToLiveMillis(), lease.getAllowedRequests()));
}
}
}
My bootstrap.yml looks as follows:
debug: true
server:
port: ${PORT:3333}
spring:
application:
name: rsocket-server
cloud:
config:
discovery:
enabled: true
service-id: config-server # should come from environment
rsocket:
server:
port: 9999
transport: tcp
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka
My pom.xml looks as follows:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.0.M6</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<groupId>com.equalities.cloud</groupId>
<artifactId>rsocket-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>rsocket-server</name>
<description>An RSocket server application</description>
<properties>
<java.version>11</java.version>
<spring-cloud.version>Hoxton.M2</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-amqp</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-rsocket</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-bus</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-zipkin</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-rabbit</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<scope>provided</scope> <!-- See: https://projectlombok.org/setup/maven -->
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>io.projectreactor</groupId>
<artifactId>reactor-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.amqp</groupId>
<artifactId>spring-rabbit-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</pluginRepository>
</pluginRepositories>
</project>
As you can see, I am using Spring-Cloud-Config (server) in combination with Spring–Boot-Starter-AMQP and Spring–Cloud-Stream-Binder-RabbitMQ.
I have debugged, where the problem comes from, and it seems to me it is either a problem of the Spring Boot RSocket support or of Spring-Cloud-Stream.
The problem is that ServerRSocketFactoryCustomizer is a #FunctionalInterface, i.e. behaves like a function and is picked up by the org.springframework.cloud.stream.function.FunctionConfiguration class, which internally calls functionCatalog.lookup(functionProperties.getDefinition()) that tries to perform a lookup for exactly one function from a registry.
As a result of me declaring the ServerRSocketFactoryCustomizer that registry contains two functions, and hence the exception is thrown.
Generally, I would expect that I can declare as many ServerRSocketFactoryCustomizer beans as I am happy to, and #Order them accordingly to influence the way the RSocket server behaves.
Today, this seems not possible, and also the Spring support for RSocket based on 'Annotated Responders' pretty much hides away the RSocket server socket, which is a bit of a shame.
Is there any way one can customize the RSocket server provided by Spring/Spring-Boot to add leases, etc., like I am trying to do?
Thanks!

Answer 1

So this is an issue where a feature of spring-cloud-function kind of get's in a way.
We are discussing it and will fix it shortly, but for now here is a quick workaround.
Simply add a property --spring.cloud.function.definition=blah where blah is something that does not exist and you should be fine.