There is a simple demo showing the usage of this component:
1) Under the shell just type: mvn exec:java
2) Point your browser to http://localhost:8080

then under the shell console start type something followed by <enter>, you'll see what you are typing into the browser.
This simple demo is under: src/main/java/org/apache/camel/component/cometd/CometdProducerConsumerInteractiveTest.java