Spring Boot Apache Camel

Overview

In this article, we'll explore how to integrate Apache Camel with Spring Boot.

What is a Apache Camel?

Apache Camel is an open-source integration framework for implementing various Enterprise Integration Patterns(EIPs), that allows you to quickly and easily connect different systems that consume or produce data.

It is easy to use Domain Specific Languages (DSLs) to wire EIPs and transports together

Camel receives messages from some endpoint and sends it to another one. The messages can be processed or simply routed to different endpoint depending on transformation logic applied in Camel.

It allows integration simple by providing connectivity to a wide variety of transports and APIs.
For example, you can easily route JMS to JSON, JSON to JMS, HTTP to JMS, FTP to JMS, even HTTP to HTTP, and connectivity to Microservices.

COMPONENTS

Component references are used to locate a component within an assembly. Apache Component References provides a variety of references that provide services for messaging, transmitting data, notifications, and a variety of other services that can not only resolve simple messaging and data transfer but also provide data security.

1. CORE COMPONENTS

   Total Core Components: 25 in 22 JAR artifacts. Some of them are Bean, log,Class, REST API, Timer, XSLT etc..

2. NON-CORE COMPONENTS

   There are total Non-Core Components: 320 in 247 JAR artifacts (1 deprecated). Some of them are activemq, amqp, atom, aws, aws lamda, kafka, aws mq, crypto etc..

In this tutorial, will start with basic example of using simple constant message using core component called timer and print the log using Log core component.

It will generate messages in specified intervals using java.util.Timer.
Syntax for timer component:

timer:timerName

For log, Apache Camel utilizes sfl4j, which enables you to configure logging through, among Log4j, Logback, Java Util Logging
Syntax for log component:

log:loggerName

Let's get started on the project now.

Project Structure

1. Create Spring Boot Maven project with Apache Camel dependencies from spring initializr
2. Apache Camel will have camel-spring-boot-starter dependency in 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 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>2.4.5</version>
   		<relativePath/> <!-- lookup parent from repository -->
   	</parent>
   	<groupId>com.techgeeknext</groupId>
   	<artifactId>camel-sprint-boot-service-a</artifactId>
   	<version>0.0.1-SNAPSHOT</version>
   	<name>camel-sprint-boot-service-a</name>
   	<description>Demo project for Spring Boot with Apache Camel</description>
   	<properties>
   		<java.version>1.8</java.version>
   	</properties>
   	<dependencies>
   		<dependency>
   			<groupId>org.springframework.boot</groupId>
   			<artifactId>spring-boot-starter-web</artifactId>
   		</dependency>
   		<dependency>
   			<groupId>org.apache.camel.springboot</groupId>
   			<artifactId>camel-spring-boot-starter</artifactId>
   			<version>3.9.0</version>
   		</dependency>
   
   	</dependencies>
   
   	<build>
   		<plugins>
   			<plugin>
   				<groupId>org.springframework.boot</groupId>
   				<artifactId>spring-boot-maven-plugin</artifactId>
   			</plugin>
   		</plugins>
   	</build>
   
   </project>
   

Building a Route

A route in Apache Camel is a collection of steps that Camel performs in order to consume and process a message. A Camel route begins with a customer and progresses through a series of endpoints and processors.

Routes in Java are found within a RouteBuilder class, which has a configure() method where you can add your route code.

Create SimpleMessageRoute class which extends RouteBuilder and override the configure method.

package com.techgeeknext.camel.routes;

import org.apache.camel.builder.RouteBuilder;
import org.springframework.stereotype.Component;

@Component
public class SimpleMessageRoute extends RouteBuilder {

    @Override
    public void configure() throws Exception {

        //generates an event/constant message every 60 seconds
        from("timer:active-mq-timer?period=60000")
                .transform().constant("Hello Message from Apache Camel - TechGeekNext")
                .log("${body}");
                //in next tutorial, will consume this message from ActiveMQ queue
               // .to("activemq:my-activemq-queue");
    }
}

from() Route With transform()

When working with Camel, a route receives parameters and then converts, transforms and process these parameters. After that, it sends these parameters to another route that forwards the result to the desired output (a file, a database, an SMTP server or a REST API response).

Start the Spring Boot Application, and you can notice that route is generating Hello constant message in every 60 seconds and logs in the consol as shown below.

[INFO] --- spring-boot-maven-plugin:2.4.5:run (default-cli) @ camel-sprint-boot-service-a ---
[INFO] Attaching agents: []

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.4.5)

10:11:52.748  INFO 9076 --- [           main] c.t.c.CamelSprintBootServiceAApplication : Starting CamelSprintBootServiceAApplication using Java 12.0.2  (D:\camel-sprint-boot-service-a\target\classes started by TechGeekNext User in D:\camel-sprint-boot-service-a)
10:11:52.750  INFO 9076 --- [           main] c.t.c.CamelSprintBootServiceAApplication : No active profile set, falling back to default profiles: default
10:11:53.894  INFO 9076 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
10:11:53.901  INFO 9076 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
10:11:53.901  INFO 9076 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.45]
10:11:54.075  INFO 9076 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
10:11:54.075  INFO 9076 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1284 ms
10:11:54.247  INFO 9076 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
10:11:54.632  INFO 9076 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
10:11:54.771  INFO 9076 --- [           main] o.a.c.impl.engine.AbstractCamelContext   : Routes startup summary (total:1 started:1)
10:11:54.772  INFO 9076 --- [           main] o.a.c.impl.engine.AbstractCamelContext   :     Started route1 (timer://active-mq-timer)
10:11:54.772  INFO 9076 --- [           main] o.a.c.impl.engine.AbstractCamelContext   : Apache Camel 3.9.0 (camel-1) started in 142ms (build:25ms init:104ms start:13ms)
10:11:54.776  INFO 9076 --- [           main] c.t.c.CamelSprintBootServiceAApplication : Started CamelSprintBootServiceAApplication in 2.351 seconds (JVM running for 2.818)
10:11:55.784  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:12:55.789  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:13:55.791  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:14:55.801  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:15:55.808  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:16:55.816  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:17:55.823  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:18:55.826  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:19:55.828  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:20:55.841  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:21:55.848  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:22:55.870  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:23:55.883  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:24:55.891  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext
10:25:55.905  INFO 9076 --- [active-mq-timer] route1 :  Hello Message from Apache Camel - TechGeekNext

In next tutorial will create Spring Boot with Apache Camel Consumer service which will consume this message using activemq.

Download Source Code

The full source code for this article can be found on below.
Download it here - Spring Boot Apache Camel Simple Message Example