Adding RouteBuilders to the CamelContext

Overview

RouteBuilder objects represent the core of a router application, because they embody the routing rules you want to implement. In the case of a standalone deployment, you must manage the lifecycle of your RouteBuilder objects explicitly, which involves instantiating the RouteBuilder classes and adding them to the CamelContext instance.

Example of adding a RouteBuilder

Example 1.3 shows the outline of the standalone main() method, highlighting details of how to add a RouteBuilder object to a CamelContext instance.

Example 1.3. Adding a RouteBuilder to the CamelContext

package org.apache.camel.example.jmstofile;
...
public class JmsToFileRoute extends RouteBuilder { 
    public void configure() {
        from("test-jms:queue:test.queue").to("file://test"); 
        // set up a listener on the file component
        from("file://test").process(new Processor() { 
            public void process(Exchange e) {
                System.out.println("Received exchange: " + e.getIn());
            }
        });
    }
}

public final class CamelJmsToFileExample {
    ...
    public static void main(String args[]) throws Exception {
        CamelContext context = new DefaultCamelContext();

        // Add components to the CamelContext.
        // ... (not shown)

        // Add routes to the CamelContext.
        context.addRoutes(new JmsToFileRoute()); 

        // Start the context.
        context.start();

        // End of main thread.
    }
}

Where the preceding code can be explained as follows:

Define a class that extends org.apache.camel.builder.RouteBuilder to define the routing rules. If required, you can define multiple RouteBuilder classes.

	Note
	When defining routes that include transactional components, you must extend `org.apache.camel.spring.SpringRouteBuilder` instead of `RouteBuilder`. See Transactional Client in Implementing Enterprise Integration Patterns.

The first route implements a hop from a JMS queue to the file system. That is, messages are read from the JMS queue, test.queue, and then written to files in the test directory. The JMS endpoint, which has a URI prefixed by test-jms, uses the JMS component registered in Example 1.2.

The second route reads (and deletes) the messages from the test directory and displays the messages in the console window. To display the messages, the route implements a custom processor (implemented inline).

Call the CamelContext.addRoutes() method to add a RouteBuilder object to the CamelContext instance.