What's the correct class to run Apache Camel 3.14.0 from command line? - apache-camel

Question

I set the following pom.xml to use Camel 3.14.0:
<?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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.apps</groupId>
<artifactId>MyApp</artifactId>
<version>1.0.0</version>
<name>MyApp Camel component</name>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-bom</artifactId>
<version>3.14.0</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-core</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-csv</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-sql</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-spring</artifactId>
</dependency>
<!-- DB dependencies -->
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>2.6.1</version>
<scope>system</scope>
<systemPath>D:\Drivers\hsqldb-2.6.1-jdk8.jar</systemPath>
</dependency>
</dependencies>
</project>
Then I have this command line in Windows to collect dependencies:
C:\Users\Public\apache-maven-3.2.5\bin\mvn -f pom.xml dependency:copy-dependencies
When I run it I get all jars in the destination folder (../build/target/dependency).
And then I get other run.bat file with following:
set CLASSPATH=../build/target/dependency/*;../config/
java -classpath "%CLASSPATH%" org.apache.camel.spring.Main
But when I run it, I get an error saying it can't find Main class. That class is the one used in previous use cases (Camel 2.10.6) and it worked fine. Would you please advise on what's the right class to reference here?
EDIT 1: I found in documentation that Main is now in org.apache.camel.main, so I configured that in run.bat and it's seems to be running. But now it shows the following and the odd thing about this is that it ceased picking the file from the path configured in context.xml. Any ideas?
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.
EDIT 2: I looked on the error and found I needed to include dependency
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
</dependency>
It still seems to work (message regarding slf4 is gone) but still won't pick file from path.
Now, reason I decided to move to last LTS version was because I needed to use a component property only available in newer version of Camel than the one I've been using. So I decided to give a shot to latest version, but now I'm stuck with error saying it can't find the class.
I've somewhat used Camel in the past but only based on examples provided by someone else, never from scratch so I'm no expert at all and unfortunately I need to solve this in a hurry. I guess the easiest would be to use a java bean but I'm no java developer so I thought it might be ok using Spring XML DSL. I'm using java 1.8.0_92.
Camel documentation doesn't seem to provide so many details as per spring xml, so any help will be greatly appreciated.

Answer 1

Frameworks and documentation
First and foremost its good to understand that Apache Camel is integration framework, Spring is application framework with probably its most notable feature being dependency injection. Due to this the documentation kinda expects the developer to be familiar with spring-framework and able juggle between camel and spring documentation.
Camel main
Camel-main in the other hand is tool you can use to run camel applications without any framework so it has no knowledge about spring framework. There's camel-spring-main but more on that later.
Spring-boot
When it comes to spring it might be easier to just use spring-boot which you can think of as collection of maven dependencies you can use to auto-configure your spring application with default configurations.
I recommend that you create a new project using camel maven archetype camel-archetype-spring-boot. This should provide you with good starting point and example on how to get started with camel and spring.
To use spring-xml files with camel-spring-boot you can add annotation #ImportResource(classpath:META-INF/spring/camel-context.xml) over your SpringBootApplication class (class annotated with #SpringBootApplication, named MySpringBootApplication when using the template).
Change the path to match the location and name of your xml-file and delete or comment the example RouteBuilder class from the project to prevent it from interrupting with anything.
# You can run spring-boot application using maven
mvn spring-boot:run
# Alternatively you should be able to run it from jar using
java -jar application.jar
Downside for spring-boot is that it'll flood our project with bunch of extra dependencies. For example to just keep the application running the template project uses spring-boot-start-web, spring-boot-starter-undertow and spring-boot-starter-actuator dependencies.
Camel Spring Main
There's also archetype camel-archetype-spring you can use to create camel spring application without spring-boot. It uses the camel-spring-main I mentioned above and can be run using maven with command mvn camel:run.
However I find this archetype a bit lacking. First it lacks visible main class which is inconsistent if you compare it to some camel-archetype-main. Secondly there seems to be problems with its packaging configurations as I didn't find an easy way to run it from jar. Most attempts I tried resulted in ClassNotFoundException for org/apache/camel/spring/Main even tough I had all maven dependencies in place. It runs fine from IDE however.
Convert your project to JAVA-DSL and use camel main
Since your route doesn't seem all that complex you could probably convert it to Java-DSL from XML in minutes and just run it with camel-main without any application framework. There's archetype for this as well called camel-archetype-main.