Processor App in Spring Boot 2.2.4/Hoxton.SR1 not working in Spring Cloud Data Flow 2.4.1

问题

I am trying to develop a new application to work on SCDF 2.4.1 and Skipper 2.3.1

I took the samples from https://github.com/sabbyanandan/stream-programming-models

I built them locally. Downloaded the docker compose for SCDF kafka, set the Versions and mount my repo and start my docker compose.

When I deploy the "function" module and create a simple stream http | customUpper | log

I see the sample working fine and able to see log output as expected.

When I modify the function stream app, to use Spring Boot, 2.2.4 and Hoxton.SR1 for cloud stream dependencies. I do not see any output in the log.

BootApp

public class FunctionStreamSampleApplication {

    public static void main(String[] args) {
        SpringApplication.run(FunctionStreamSampleApplication.class, args);
    }

    @Bean
    public Function<String, String> uppercase() {

        return data -> {
            System.out.println("Input "+data);
            return data.toUpperCase();
        };
    }
}

application.yml
spring:
  cloud:
    stream:
      function:
        definition: uppercase

pom.xml
<?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 http://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>2.2.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <artifactId>function219</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>function219</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-function-context</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-stream-binder-kafka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-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>

</project>

I have removed the test classes just to strip it to bare minimum to avoid other dependency. The same app does work when deployed as is using the 2.1.4 version of spring boot it was originally built on. Do let know if there are changes needed to be done to make it work on SCDF

When i use kafkatools to check the topics created by the stream, I see messages only in the streamname.http, but processor doesnt seem to be reading messages as my sysout is not getting printed.

回答1:

I believe the problem is that the current published stream apps, http and log, use an earlier version of spring-cloud-stream, based on spring boot 2.1.x. The newer version of spring-cloud-stream that is compatible with boot 2.2.x is not backwards compatible. All apps in the stream must be on the same (or compatible) spring-cloud-stream versions. I expect if you look at the log for custom processor, you will see some conversion error.

回答2:

For function based stream modules to work with SCDF, you need to add the appropriate binding name properties to input and output to your application properties as described here: https://cloud.spring.io/spring-cloud-static/spring-cloud-stream/3.0.3.RELEASE/reference/html/spring-cloud-stream.html#_functional_binding_names

Essentially, this maps the functional binding endpoint names to the SCDF endpoint names, input and output. For example, if you have a Function `foo':

spring.cloud.stream.function.bindings.foo-in-0=input spring.cloud.stream.function.bindings.foo-out-0=output

.Future releases of the prepackaged stream modules will use the Functional paradigm and will provide these properties automatically.

来源：https://stackoverflow.com/questions/60856691/processor-app-in-spring-boot-2-2-4-hoxton-sr1-not-working-in-spring-cloud-data-f