Using Apache Camel/Smallrye/reactive streams - how can I connect a "publisher" to a "subscriber" across JVMs?

Asked 4/12, 2019 at 22:14 Answered 6/1, 2020 at 14:6

Solved java apache-camel reactive-programming activemq-artemis smallrye

Below is my attempt at a Apache Camel reactive streams solution to connect a publisher to a subscriber (code for camel routes is shown below) across JVM's

To enable the communication to span JVMs, it seems a "broker" server is required. Therefore, I've implemented Artemis broker and modified application.properties files accordingly (as per my best understanding of how to do so).

Also, to narrow the focus, have chosen to use the smallrye-ampq connector.

Problem:

The subscriber should be receiving and logging the the String value (from the body):

-
-
-
:blahblahblah
:blahblahblah
:blahblahblah
-
-
-

--Instead, it is logging the values, like this:

-
-
-
:Exchange[ID-LAPTOP-4LR4PMVQ-1576639597494-0-289]
:Exchange[ID-LAPTOP-4LR4PMVQ-1576639597494-0-292]
:Exchange[ID-LAPTOP-4LR4PMVQ-1576639597494-0-295]
-
-
-

Question:

why is the payload send by the publisher not reaching the subscriber and what code/configuration can I modify to fix it?

thx in advance for any help!

---

The "Publisher" route

package aaa.bbb.ccc.jar;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import org.eclipse.microprofile.reactive.messaging.Outgoing;
import org.reactivestreams.Publisher;
import org.apache.camel.CamelContext;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.reactive.streams.api.CamelReactiveStreamsService;
import org.apache.camel.component.reactive.streams.api.CamelReactiveStreams;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;

@ApplicationScoped
public class CamelPub extends RouteBuilder {

    @Inject
    CamelContext ctx;

    CamelReactiveStreamsService crss;
    static int x = 0;

    @Outgoing("data")
    public Publisher<Exchange> source() {
        return crss.from("seda:thesource");
    }

    @Override
    public void configure() {

        crss = CamelReactiveStreams.get(ctx);
        from("timer://thetimer?period=1000")
                .process(new Processor() {
                    @Override
                    public void process(Exchange msg) throws Exception {
                        msg.getIn().setBody("blahblahblah"); //(Integer.toString(x++));
                    }
                })
                .log("....... PUB ....... camelpub - body: ${body}")
                .to("direct:thesource");
    }
}

microprofile-config.properties - publisher

injected.value=Injected value
value=lookup value
# Microprofile server properties
server.port=8084
server.host=0.0.0.0

mp.messaging.outgoing.data.connector=smallrye-amqp
mp.messaging.outgoing.data.host=localhost
mp.messaging.outgoing.data.port=5672
mp.messaging.outgoing.data.username=artuser
mp.messaging.outgoing.data.password=artpassword
mp.messaging.outgoing.data.endpoint-uri:seda:thesource
mp.messaging.outgoing.data.broadcast=true
mp.messaging.outgoing.data.durable=true

relevant console log excerpt(?) - publisher

...
--- exec-maven-plugin:1.5.0:exec (default-cli) @ camelpub ---
2019.12.17 22:26:34 INFO io.helidon.microprofile.server.Main Thread[main,5,main]: Logging configured using classpath: /logging.properties
2019.12.17 22:26:35 INFO org.jboss.weld.Version Thread[main,5,main]: WELD-000900: 3.1.1 (Final)
2019.12.17 22:26:35 INFO org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-ENV-000020: Using jandex for bean discovery
2019.12.17 22:26:35 WARN org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-001208: Error when validating null@6 against xsd. cvc-complex-type.4: Attribute 'bean-discovery-mode' must appear on element 'beans'.
2019.12.17 22:26:35 INFO org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-000101: Transactional services not available. Injection of @Inject UserTransaction not available. Transactional observers will be invoked synchronously.
2019.12.17 22:26:36 INFO org.jboss.weld.Event Thread[main,5,main]: WELD-000411: Observer method [BackedAnnotatedMethod] public org.glassfish.jersey.ext.cdi1x.internal.ProcessAllAnnotatedTypes.processAnnotatedType(@Observes ProcessAnnotatedType<?>, BeanManager) receives events for all annotated types. Consider restricting events using @WithAnnotations or a generic type with bounds.
2019.12.17 22:26:36 INFO org.jboss.weld.Event Thread[main,5,main]: WELD-000411: Observer method [BackedAnnotatedMethod] private io.helidon.microprofile.openapi.IndexBuilder.processAnnotatedType(@Observes ProcessAnnotatedType<X>) receives events for all annotated types. Consider restricting events using @WithAnnotations or a generic type with bounds.
2019.12.17 22:26:36 INFO org.jboss.weld.Event Thread[main,5,main]: WELD-000411: Observer method [BackedAnnotatedMethod] private org.apache.camel.cdi.CdiCamelExtension.processAnnotatedType(@Observes ProcessAnnotatedType<?>) receives events for all annotated types. Consider restricting events using @WithAnnotations or a generic type with bounds.
2019.12.17 22:26:36 WARN org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-001101: Member of array type or annotation type must be annotated @NonBinding:  [EnhancedAnnotatedMethodImpl] public abstract javax.enterprise.inject.Typed.value()
2019.12.17 22:26:36 INFO org.apache.camel.cdi.CdiCamelExtension Thread[main,5,main]: Camel CDI is starting Camel context [camel-1]
2019.12.17 22:26:36 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Apache Camel 3.0.0 (CamelContext: camel-1) is starting
2019.12.17 22:26:36 INFO org.apache.camel.impl.engine.DefaultManagementStrategy Thread[main,5,main]: JMX is disabled
2019.12.17 22:26:37 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: StreamCaching is not in use. If using streams then its recommended to enable stream caching. See more details at http://camel.apache.org/stream-caching.html
2019.12.17 22:26:37 INFO org.apache.camel.component.seda.SedaEndpoint Thread[main,5,main]: Endpoint seda://thesource is using shared queue: seda://thesource with size: 1000
2019.12.17 22:26:37 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Route: route1 started and consuming from: timer://thetimer?period=1000
2019.12.17 22:26:37 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Total 1 routes, of which 1 are started
2019.12.17 22:26:37 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Apache Camel 3.0.0 (CamelContext: camel-1) started in 0.191 seconds
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.extension.ReactiveMessagingExtension Thread[main,5,main]: Analyzing mediator bean: Managed Bean [class aaa.bbb.ccc.jar.CamelPub] with qualifiers [@Any @Default]
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Scanning Type: class aaa.bbb.ccc.jar.CamelPub
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Deployment done... start processing
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.impl.ConfiguredChannelFactory Thread[main,5,main]: Found incoming connectors: []
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.impl.ConfiguredChannelFactory Thread[main,5,main]: Found outgoing connectors: []
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.impl.ConfiguredChannelFactory Thread[main,5,main]: Stream manager initializing...
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Initializing mediators
2019.12.17 22:26:37 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Route: route2 started and consuming from: seda://thesource
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Connecting mediators
2019.12.17 22:26:37 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Connecting method aaa.bbb.ccc.jar.CamelPub#source to sink data
2019.12.17 22:26:37 INFO org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-ENV-002003: Weld SE container e71e38c0-91ec-4758-a310-55f1368c6a9c initialized
2019.12.17 22:26:37 WARNING io.helidon.microprofile.server.Server$Builder Thread[main,5,main]: Failed to find JAX-RS resource to use
2019.12.17 22:26:37 INFO io.helidon.microprofile.security.SecurityMpService Thread[main,5,main]: Security extension for microprofile is enabled, yet security configuration is missing from config (requires providers configuration at key security.providers). Security will not have any valid provider.
2019.12.17 22:26:37 INFO io.smallrye.openapi.api.OpenApiDocument Thread[main,5,main]: OpenAPI document initialized: io.smallrye.openapi.api.models.OpenAPIImpl@57fbc06f
2019.12.17 22:26:38 INFO route1 Thread[Camel (camel-1) thread #1 - timer://thetimer,5,main]: ....... PUB ....... camelpub - body: 0
2019.12.17 22:26:38 INFO io.helidon.webserver.NettyWebServer Thread[main,5,main]: Version: 1.4.0
2019.12.17 22:26:38 INFO io.helidon.webserver.NettyWebServer Thread[nioEventLoopGroup-2-1,10,main]: Channel '@default' started: [id: 0x52928b67, L:/0:0:0:0:0:0:0:0:8084]
2019.12.17 22:26:38 INFO io.helidon.microprofile.server.ServerImpl Thread[nioEventLoopGroup-2-1,10,main]: Server initialized on http://localhost:8084 (and all other host addresses) in 3668 milliseconds.
2019.12.17 22:26:39 INFO route1 Thread[Camel (camel-1) thread #1 - timer://thetimer,5,main]: ....... PUB ....... camelpub - body: 1
2019.12.17 22:26:40 INFO route1 Thread[Camel (camel-1) thread #1 - timer://thetimer,5,main]: ....... PUB ....... camelpub - body: 2
2019.12.17 22:26:41 INFO route1 Thread[Camel (camel-1) thread #1 - timer://thetimer,5,main]: ....... PUB ....... camelpub - body: 3
2019.12.17 22:26:42 INFO route1 Thread[Camel (camel-1) thread #1 - timer://thetimer,5,main]: ....... PUB ....... camelpub - body: 4
...

the "Subscriber" route

package aaa.bbb.ccc.jar;

import javax.inject.Inject;
import org.apache.camel.CamelContext;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.reactive.streams.api.CamelReactiveStreamsService;
import javax.enterprise.context.ApplicationScoped;
import org.apache.camel.component.reactive.streams.api.CamelReactiveStreams;
import org.eclipse.microprofile.reactive.messaging.Incoming;
import org.reactivestreams.Subscriber;

@ApplicationScoped
public class CamelSub extends RouteBuilder {

    public CamelSub() throws Exception {
    }

    @Inject
    CamelContext ctx;

    CamelReactiveStreamsService crss;

    @Incoming("data")
    public Subscriber<String> sink() {
    return crss.subscriber("seda:thesink", String.class);
    }    

    @Override
    public void configure() {

    crss = CamelReactiveStreams.get(ctx);

    from("seda:thesink")
        .convertBodyTo(String.class)
        .log("ooooooo SUB ooooooo camelsub - body: ${body}");
    }
}

microprofile-config.properties - subscriber

injected.value=Injected value
value=lookup value
# Microprofile server properties
server.port=8082
server.host=0.0.0.0

mp.messaging.incoming.data.connector=smallrye-amqp
mp.messaging.incoming.data.host=localhost
mp.messaging.incoming.data.port=5672
mp.messaging.incoming.data.username=artuser
mp.messaging.incoming.data.password=artpassword
mp.messaging.incoming.data.endpoint-uri:seda:thesink
mp.messaging.incoming.data.broadcast=true
mp.messaging.incoming.data.durable=true

relevant console log excerpt(?) - subscriber

...
--- exec-maven-plugin:1.5.0:exec (default-cli) @ camelsub ---
2019.12.17 22:28:09 INFO io.helidon.microprofile.server.Main Thread[main,5,main]: Logging configured using classpath: /logging.properties
2019.12.17 22:28:10 INFO org.jboss.weld.Version Thread[main,5,main]: WELD-000900: 3.1.1 (Final)
2019.12.17 22:28:10 INFO org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-ENV-000020: Using jandex for bean discovery
2019.12.17 22:28:10 WARN org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-001208: Error when validating null@6 against xsd. cvc-complex-type.4: Attribute 'bean-discovery-mode' must appear on element 'beans'.
2019.12.17 22:28:10 INFO org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-000101: Transactional services not available. Injection of @Inject UserTransaction not available. Transactional observers will be invoked synchronously.
2019.12.17 22:28:10 INFO org.jboss.weld.Event Thread[main,5,main]: WELD-000411: Observer method [BackedAnnotatedMethod] public org.glassfish.jersey.ext.cdi1x.internal.ProcessAllAnnotatedTypes.processAnnotatedType(@Observes ProcessAnnotatedType<?>, BeanManager) receives events for all annotated types. Consider restricting events using @WithAnnotations or a generic type with bounds.
2019.12.17 22:28:10 INFO org.jboss.weld.Event Thread[main,5,main]: WELD-000411: Observer method [BackedAnnotatedMethod] private io.helidon.microprofile.openapi.IndexBuilder.processAnnotatedType(@Observes ProcessAnnotatedType<X>) receives events for all annotated types. Consider restricting events using @WithAnnotations or a generic type with bounds.
2019.12.17 22:28:10 INFO org.jboss.weld.Event Thread[main,5,main]: WELD-000411: Observer method [BackedAnnotatedMethod] private org.apache.camel.cdi.CdiCamelExtension.processAnnotatedType(@Observes ProcessAnnotatedType<?>) receives events for all annotated types. Consider restricting events using @WithAnnotations or a generic type with bounds.
2019.12.17 22:28:10 WARN org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-001101: Member of array type or annotation type must be annotated @NonBinding:  [EnhancedAnnotatedMethodImpl] public abstract javax.enterprise.inject.Typed.value()
2019.12.17 22:28:11 INFO org.apache.camel.cdi.CdiCamelExtension Thread[main,5,main]: Camel CDI is starting Camel context [camel-1]
2019.12.17 22:28:11 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Apache Camel 3.0.0 (CamelContext: camel-1) is starting
2019.12.17 22:28:11 INFO org.apache.camel.impl.engine.DefaultManagementStrategy Thread[main,5,main]: JMX is disabled
2019.12.17 22:28:11 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: StreamCaching is not in use. If using streams then its recommended to enable stream caching. See more details at http://camel.apache.org/stream-caching.html
2019.12.17 22:28:11 INFO org.apache.camel.component.seda.SedaEndpoint Thread[main,5,main]: Endpoint seda://thesink is using shared queue: seda://thesink with size: 1000
2019.12.17 22:28:11 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Route: route1 started and consuming from: seda://thesink
2019.12.17 22:28:11 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Total 1 routes, of which 1 are started
2019.12.17 22:28:11 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Apache Camel 3.0.0 (CamelContext: camel-1) started in 0.173 seconds
2019.12.17 22:28:11 INFO io.smallrye.reactive.messaging.extension.ReactiveMessagingExtension Thread[main,5,main]: Analyzing mediator bean: Managed Bean [class aaa.bbb.ccc.jar.CamelSub] with qualifiers [@Any @Default]
2019.12.17 22:28:11 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Scanning Type: class aaa.bbb.ccc.jar.CamelSub
2019.12.17 22:28:11 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Deployment done... start processing
2019.12.17 22:28:11 INFO io.smallrye.reactive.messaging.impl.ConfiguredChannelFactory Thread[main,5,main]: Found incoming connectors: []
2019.12.17 22:28:11 INFO io.smallrye.reactive.messaging.impl.ConfiguredChannelFactory Thread[main,5,main]: Found outgoing connectors: []
2019.12.17 22:28:11 INFO io.smallrye.reactive.messaging.impl.ConfiguredChannelFactory Thread[main,5,main]: Stream manager initializing...
2019.12.17 22:28:12 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Initializing mediators
2019.12.17 22:28:12 INFO org.apache.camel.impl.DefaultCamelContext Thread[main,5,main]: Route: route2 started and consuming from: reactive-streams://ID-LAPTOP-4LR4PMVQ-1576639692145-0-1
2019.12.17 22:28:12 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Connecting mediators
2019.12.17 22:28:12 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Attempt to resolve aaa.bbb.ccc.jar.CamelSub#sink
2019.12.17 22:28:12 INFO io.smallrye.reactive.messaging.extension.MediatorManager Thread[main,5,main]: Connecting aaa.bbb.ccc.jar.CamelSub#sink to `data` (org.eclipse.microprofile.reactive.streams.operators.core.PublisherBuilderImpl@3eda0aeb)
2019.12.17 22:28:12 INFO org.jboss.weld.Bootstrap Thread[main,5,main]: WELD-ENV-002003: Weld SE container c1eaa1fb-486c-4b95-b56b-0f1a7b88f741 initialized
2019.12.17 22:28:12 WARNING io.helidon.microprofile.server.Server$Builder Thread[main,5,main]: Failed to find JAX-RS resource to use
2019.12.17 22:28:12 INFO io.helidon.microprofile.security.SecurityMpService Thread[main,5,main]: Security extension for microprofile is enabled, yet security configuration is missing from config (requires providers configuration at key security.providers). Security will not have any valid provider.
2019.12.17 22:28:12 INFO io.smallrye.openapi.api.OpenApiDocument Thread[main,5,main]: OpenAPI document initialized: io.smallrye.openapi.api.models.OpenAPIImpl@77f905e3
2019.12.17 22:28:12 INFO io.helidon.webserver.NettyWebServer Thread[main,5,main]: Version: 1.4.0
2019.12.17 22:28:12 INFO io.helidon.webserver.NettyWebServer Thread[nioEventLoopGroup-2-1,10,main]: Channel '@default' started: [id: 0xd8f72801, L:/0:0:0:0:0:0:0:0:8082]
2019.12.17 22:28:12 INFO io.helidon.microprofile.server.ServerImpl Thread[nioEventLoopGroup-2-1,10,main]: Server initialized on http://localhost:8082 (and all other host addresses) in 3310 milliseconds.
2019.12.17 22:28:13 INFO route1 Thread[Camel (camel-1) thread #1 - seda://thesink,5,main]: ooooooo SUB ooooooo camelsub - body: Exchange[ID-LAPTOP-4LR4PMVQ-1576639597494-0-289]
2019.12.17 22:28:14 INFO route1 Thread[Camel (camel-1) thread #1 - seda://thesink,5,main]: ooooooo SUB ooooooo camelsub - body: Exchange[ID-LAPTOP-4LR4PMVQ-1576639597494-0-292]
2019.12.17 22:28:15 INFO route1 Thread[Camel (camel-1) thread #1 - seda://thesink,5,main]: ooooooo SUB ooooooo camelsub - body: Exchange[ID-LAPTOP-4LR4PMVQ-1576639597494-0-295]    
...

NOTE: above output should be showing numbers... rather than, e.g., "Exchange[ID-LAPTOP-4LR4PMVQ-1576639597494-0-289]", etc... :-(

essentially same maven pom.xml for each

<?xml version="1.0" encoding="UTF-8"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <groupId>aaa.bbb.ccc</groupId>
    <artifactId>[NOTE: essentially same pom.xml for both camelpub or camelsub]</artifactId>
    <version>1.0</version>
    <properties>
        <helidonVersion>1.4.0</helidonVersion>
        <package>aaa.bbb.ccc.jar</package>
        <failOnMissingWebXml>false</failOnMissingWebXml>
        <mpVersion>3.2</mpVersion>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <libs.classpath.prefix>libs</libs.classpath.prefix>
        <mainClass>io.helidon.microprofile.server.Main</mainClass>
        <jersey.version>2.29</jersey.version>
        <copied.libs.dir>${project.build.directory}/${libs.classpath.prefix}</copied.libs.dir>
        <camelversion>3.0.0</camelversion>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.eclipse.microprofile</groupId>
            <artifactId>microprofile</artifactId>
            <version>${mpVersion}</version>
            <type>pom</type>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.eclipse.microprofile.reactive.messaging</groupId>
            <artifactId>microprofile-reactive-messaging-api</artifactId>
            <version>1.0</version>
            <type>jar</type>
        </dependency>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>8.0</version>
            <type>jar</type>
        </dependency> 
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-core</artifactId>
            <version>${camelversion}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-reactive-streams</artifactId>
            <version>${camelversion}</version>
        </dependency>       
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-cdi</artifactId>
            <version>${camelversion}</version>
        </dependency>                              
        <dependency>
            <groupId>io.smallrye.reactive</groupId>
            <artifactId>smallrye-reactive-messaging-provider</artifactId>
            <version>1.0.8</version>
        </dependency>          
        <dependency>
            <groupId>io.smallrye.reactive</groupId>
            <artifactId>smallrye-reactive-messaging-amqp</artifactId>
            <version>1.0.8</version>
        </dependency>          
        <dependency>
            <groupId>javax.enterprise</groupId>
            <artifactId>cdi-api</artifactId>
            <version>2.0</version>
        </dependency>          
        <dependency>
            <groupId>io.helidon</groupId>
            <artifactId>helidon-bom</artifactId>
            <version>${helidonVersion}</version>
            <type>pom</type>
        </dependency>
        <dependency>
            <groupId>org.jboss</groupId>
            <artifactId>jandex</artifactId>
            <version>2.1.1.Final</version>
            <scope>runtime</scope>
            <optional>true</optional>            
        </dependency>
        <dependency>
            <groupId>javax.activation</groupId>
            <artifactId>javax.activation-api</artifactId>
            <version>1.2.0</version>
            <scope>runtime</scope>            
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-json-binding</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>io.helidon.microprofile.bundles</groupId>
            <artifactId>helidon-microprofile-3.0</artifactId>
            <version>${helidonVersion}</version>
        </dependency>
    </dependencies>
    <build>
        <finalName>[NOTE: essentially same pom.xml for both camelpub or camelsub]</finalName>
        <plugins>                             
            <plugin>
                <artifactId>maven-jar-plugin</artifactId>
                <version>2.5</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>${libs.classpath.prefix}</classpathPrefix>
                            <mainClass>${mainClass}</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>2.9</version>
                <executions>
                    <execution>
                        <id>copy-dependencies</id>
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${copied.libs.dir}</outputDirectory>
                            <overWriteReleases>false</overWriteReleases>
                            <overWriteSnapshots>false</overWriteSnapshots>
                            <overWriteIfNewer>true</overWriteIfNewer>
                            <overWriteIfNewer>true</overWriteIfNewer>
                            <includeScope>runtime</includeScope>
                            <excludeScope>test</excludeScope>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

docker-compose.yml (Artemis)

# A docker compose file to start an Artemis AMQP broker
# more details on https://github.com/vromero/activemq-artemis-docker.
version: '2'

services:

  artemis:
    image: vromero/activemq-artemis:2.8.0-alpine
    ports:
      - "8161:8161"
      - "61616:61616"
      - "5672:5672"
    environment:
      ARTEMIS_USERNAME: artuser
      ARTEMIS_PASSWORD: artpassword

technologies used

java 8
apache camel
smallrye
artemis
reactive streams/programming

(was using this link as a resource: https://smallrye.io/smallrye-reactive-messaging/)

Epitaph answered 4/12, 2019 at 22:14 Comment(10)

Did you try to use the vm component instead of seda? seda only works in a single CamelContext, hence doesn't work in two different applications. – Thies 11/12, 2019 at 16:52

I will try that. thx! – Epitaph 11/12, 2019 at 16:55

Not an answer, but I assume that application.properties, if it is read at all, is read by Camel, since Helidon does not read it by default. Additionally, I note that you have @Startup, which is an EJB annotation, and Helidon deliberately does not support EJB, so this annotation will be ignored. – Bataan 11/12, 2019 at 17:0

I'm also wondering about mp.messaging.outgoing.data.host=0.0.0.0 and right after that mp.messaging.outgoing.data.host=8084, the same is for the inbound properties, though this won't be the reason I'm pretty sure – Melesa 11/12, 2019 at 17:21

FWIW, @ClausIbsen has a similar example in his book Camel in Action 2 in Chapter 20 – Melesa 11/12, 2019 at 17:44

thx, for comments! :-) (e.g., this was one of many iterations - I have used "localhost" in place of "0.0.0.0"). what I seem to be unable to nail down is what exactly the "wiring" properties/values should be in order to accomplish communication between the publisher and subscriber. Seems exchanging "seda:" for "vm:" made no difference(?) – Epitaph 11/12, 2019 at 19:32

also - changing the erroneous host property to port (for the 8084). not sure if that was a cut-n-paste error when creating this post, but, am checking now. thx! – Epitaph 11/12, 2019 at 19:44

revised the application.properties file (fixed the port property). removed the "@Startup" annotation from both the publisher and subscriber routes. --Also, add the exceptions I am seeing now - for both publisher and subsciber. – Epitaph 11/12, 2019 at 19:56

@Epitaph yes, vm doesn't help, it'll only work in the same VM. – Thies 11/12, 2019 at 22:19

seems the application.properties has no proper effect. switched (for now) all configuration to microprofile-config.properties - thanks again for the helpful observations! – Epitaph 18/12, 2019 at 3:48

So, it turns out that changing the method signature from...

@Outgoing("data")
public Publisher<Exchange> source() {
    ...
}

to...

@Outgoing("data")
public Publisher<String> source() {
    ...
}

fixes the issue so that the subscriber now receives and logs the value/payload sent by the publisher

Epitaph answered 6/1, 2020 at 14:6 Comment(0)

The problem you have stated in your post is a fairly common use case with some well-defined patterns for solving the problem, which in this case would reasonably involve setting up some sort of asynchronous messaging middleware such as Apache ActiveMQ, RabbitMQ, Apache Kafka, etc. Doing so gives you a perfect way to decouple your Camel contexts as mentioned in the article Why Use Multiple Camel Contexts? This concept is further explained in the Apache Camel documentation for the Message Channel EIP (EIP = Enterprise Integration Pattern).

I see in your post above that you appear to be trying to use Camel SEDA. Its documentation page states:

Note that queues are only visible within a single CamelContext. If you want to communicate across CamelContext instances (for example, communicating between Web applications), see the VM component.

This component does not implement any kind of persistence or recovery, if the VM terminates while messages are yet to be processed. If you need persistence, reliability or distributed SEDA, try using either JMS or ActiveMQ.

The Camel VM component would not work for you here either since your multiple Camel contexts are distributed across different servers. The VM component can run between multiple Camel contexts, but they must all be running within the same JVM in order to inter-communicate.

For these reasons, I don't see any way around using some sort of messaging middleware in this case.

Since you mentioned streaming, something like Apache Kafka may be a good choice. I've not worked with this before and couldn't comment much further on it, but I found an article where a fella talks about it (see Reactive Streams for Apache Kafka). Camel has a Kafka Component that could be used to wire everything together.

Atworth answered 11/12, 2019 at 23:26 Comment(7)

Is a "broker" required. I had been using the camel smallrye documentation found here(smallrye.io/smallrye-reactive-messaging). Although, the documentation references configuration involving a broker for, say, "MQTT", "KAFKA" and "AMPQ" - for integrating Apache Camel it did not seem to. --Is a "broker" indeed a requirement to connect the "subscriber" camel route to the "publisher" camel route when they are on separate servers/ports? – Epitaph 12/12, 2019 at 0:10

A broker would not be required if you were running multiple web applications within the same JVM. In that case, I'd use the Camel VM component, which allows for communication between multiple Camel contexts, but only within the same JVM. You mentioned, however, that your Camel applications are distributed across multiple servers, in which case, some sort of broker is generally accepted to be the appropriate solution. Have a quick look at some of the articles I linked to in my answer. Most are fairly short and reasonably non-technical. I'm happy to answer any other questions as needed. – Atworth 12/12, 2019 at 0:15

You betcha. Also, if you feel I gave the correct answer to your question, don't forget to mark it as such :) – Atworth 12/12, 2019 at 1:1

you can be certain. :-) – Epitaph 12/12, 2019 at 2:5

Hi Eric - I've just configured artemis as my broker. still no success. the "rub" is the lack of cogent documentation and/or an examples on how to "wire up" the application.properties (for the "publisher"/"subscriber" camel routes) to get my scenario (above) to work. It seems that this is what I really need. Let me know if you have any insight on the proper "properties" wiring to make the above scenario work (assuming artemis broker). Getting late - I will post my "artemis" related changes/console output - including application properties, tomorrow. thx, again! – Epitaph 12/12, 2019 at 4:18

I just looked up Artemis. It looks to be the new version of Apache ActiveMQ. This is a good choice. – Atworth 12/12, 2019 at 4:44

Let us continue this discussion in chat. – Atworth 12/12, 2019 at 4:54

Not a generic simple camel answer, but RSocket implements the RX programming model across the network (on top of TCP sockets, HTTP Websockets etc).

https://github.com/rsocket/rsocket-java

It's well supported by app frameworks like Spring Boot. But it's not the simple just works example you are asking for.

Bluegreen answered 14/12, 2019 at 13:58 Comment(1)

Thank you for you response, Yuri. According to SmallRye/Camel documentation, the approach I am using should work. I'm assuming, for now, that the reason I've had no "breakthru" is due to my lack of misunderstanding of how application.properties should be wielded to configure a successful connection. (I realize, it could also be possible there's an issue with dependency versions[?]... -I have thrashed around [in a not so systematic way] tackling that angle, as well - but, with no success). – Epitaph 14/12, 2019 at 22:2

So, it turns out that changing the method signature from...

@Outgoing("data")
public Publisher<Exchange> source() {
    ...
}

to...

@Outgoing("data")
public Publisher<String> source() {
    ...
}

fixes the issue so that the subscriber now receives and logs the value/payload sent by the publisher

Epitaph answered 6/1, 2020 at 14:6 Comment(0)

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