Java

Based on wikipedia, Apache Camel is an open source framework for message-oriented middleware with a rule-based routing and mediation engine that provides a Java object-based implementation of the Enterprise Integration Patterns.

The good thing about Apache Camel is that it also has a great flexibility where we can deploy Apache Camel on top of Spring Boot, providing an agile microservice EIP and SOA approach.

So lets start by defining what kind of libraries needed for this project,

<?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>

    <groupId>com.edw</groupId>
    <artifactId>camel-hello-world</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <camel.version>3.17.0</camel.version>
        <spring-boot.version>2.7.1</spring-boot.version>
        <start-class>com.edw.Applicationn</start-class>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.apache.camel.springboot</groupId>
                <artifactId>camel-spring-boot-dependencies</artifactId>
                <version>${camel.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <!--        spring boot     -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-undertow</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>junit</groupId>
                    <artifactId>junit</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <!--        camel   -->
        <dependency>
            <groupId>org.apache.camel.springboot</groupId>
            <artifactId>camel-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-test-spring-junit5</artifactId>
            <scope>test</scope>
        </dependency>

        <!--        unit test   -->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.rest-assured</groupId>
            <artifactId>rest-assured</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.rest-assured</groupId>
            <artifactId>json-path</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>${start-class}</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-failsafe-plugin</artifactId>
                <version>3.0.0-M5</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>integration-test</goal>
                            <goal>verify</goal>
                        </goals>
                    </execution>
                </executions>

                <configuration>
                    <classpathDependencyExcludes>
                        <classpathDependencyExcludes>${project.groupId}:${project.artifactId}
                        </classpathDependencyExcludes>
                    </classpathDependencyExcludes>
                    <additionalClasspathElements>
                        <additionalClasspathElement>${project.build.outputDirectory}</additionalClasspathElement>
                    </additionalClasspathElements>
                    <reportsDirectory>${project.build.directory}/surefire-reports</reportsDirectory>
                </configuration>
            </plugin>

        </plugins>
    </build>

</project>

Create a java main class,

package com.edw;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

A Spring controller, where we call Camel’s route

package com.edw.controller;

import org.apache.camel.ProducerTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;

@RestController
@RequestMapping("/api")
public class ApiController {

    @Autowired
    private ProducerTemplate template;

    @GetMapping("/v1/hello")
    public HashMap getHello(@RequestParam("name") String name) {
        return (HashMap) template.requestBody("direct:getHelloWorld", name);
    }
}

And a Camel Route to do all the Enterprise Integration Pattern, where it do a json response

package com.edw.route;

import org.apache.camel.builder.RouteBuilder;
import org.springframework.stereotype.Component;
import java.util.HashMap;

@Component
public class ApiRoute extends RouteBuilder {

    @Override
    public void configure() {
        // say helloworld
        from("direct:getHelloWorld")
                .routeId("getHelloWorld")
                .tracing()
                .log("calling getHelloWorld")
                .process(exchange -> {
                    String name = (String) exchange.getIn().getBody();
                    exchange.getMessage().setBody(new HashMap<>(){{
                        put("hello", name);
                    }});
                })
                .end();
    }
}

Code for this post can be found on below github repo,

https://github.com/edwin/spring-boot-camel-hello-world

Have fun with Spring Boot and Camel 🙂