Setting up Camel via Maven

Create a new project

Within shell, move to your Eclipse workspace and create a new project.

mvn archetype:generate

In the interactive mode, use the default archetype (press Enter) with latest version (press Enter), fill in the group ID (sk.upjs.ics.novotnyr), artifact ID (camel-xmpp-example) and use the default values for version and package.

A directory camel-xmpp-example·is created with a conventional subdirectory structure and a pom.xml.

Upgrade to JDK6

Camel is built upon JDK6. However, Maven uses JDK5 by default and therefore the default target is JDK5. Upgrade your configuration to create JDK6 compatible files.

<plugins>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.3.2</version>
        <configuration>
            <source>1.6</source>
            <target>1.6</target>
        </configuration>
    </plugin>
</plugins>

Camel dependencies

Add the following Camel dependency into pom.xml

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-core</artifactId>
  <version>2.9.0</version>
</dependency>

and compile project.

mvn compile

Maven will download dependencies from Maven Central repository.

Testing a simple route

For test, we will use a simple stdin-stdout route according to the example code on the Camel website. We will type into the console, thus generating messages and Camel will route via Stream Component and print them to the System.out.

Add a Stream Component dependency

Add a dependendy into your pom.xml

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-stream</artifactId>
    <version>2.9.0</version>
</dependency>

Code the client

Instead of DefaultCamelContext, we use the utility class org.apache.camel.main.Main, which allows us to spawn a Camel context and keep it running, while receiving our messages from stdin,.

package sk.upjs.ics.novotnyr;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.main.Main;
public class CamelTest {
    public static void main(String[] args) throws Exception {
        Main camelMain = new Main();
        camelMain.enableHangupSupport();
        camelMain.addRouteBuilder(new RouteBuilder() {
            @Override
            public void configure() throws Exception {
                from("stream:in").to("stream:out");
            }
        });
        camelMain.run();
    }
}

Running the code produces a strange logging error:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

Resolve it by adding a proper SLF4J logging implementation, for example logback.

<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.0.0</version>
</dependency>

Running the example once again launches a context. Now we can submit messages by typing into the console. Camel will log each message delivery.

Typing

Hello World

will log

14:20:13.356 [Camel (camel-1) thread #1 - stream://in] DEBUG o.a.camel.processor.SendProcessor - >>>> Endpoint[stream://out] Exchange[Message: Hello World]
14:20:13.356 [Camel (camel-1) thread #1 - stream://in] DEBUG o.a.c.c.stream.StreamProducer - Writing as text: Hello World to java.io.PrintStream@1ee29820 using encoding: UTF-8
Hello World

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Mounting the Camel: A stdin-stdout example