POJO producing

There are two different ways to send messages to any Camel Endpoint from a POJO.

[[POJOProducing-@EndpointInject]] = Via @EndpointInject

To allow sending of messages from POJOs you can use the org.apache.camel.EndpointInject annotation. This will inject a org.apache.camel.ProducerTemplate so that the bean can participate in message exchanges.

Example: send a message to the foo.bar ActiveMQ queue:

public class Foo {
  @EndpointInject(uri="activemq:foo.bar")
  ProducerTemplate producer;

  public void doSomething() {
    if (whatever) {
      producer.sendBody("<hello>world!</hello>");
    }
  }
}

The downside of this is that your code is now dependent on a Camel API, the ProducerTemplate. The next section describes how to remove this dependency.

[[POJOProducing-HidingtheCamelAPIsFromYourCodeUsing@Produce]] == Hiding the Camel APIs From Your Code Using @Produce

We recommend Hiding Middleware APIs from your application code so the next option might be more suitable. You can add the @Produce annotation to an injection point (a field or property setter) using a ProducerTemplate or using some interface you use in your business logic. Example:

public interface MyListener {
    String sayHello(String name);
}

public class MyBean {
    @Produce(uri = "activemq:foo")
    protected MyListener producer;

    public void doSomething() {
        // lets send a message
        String response = producer.sayHello("James");
    }
}

Here Camel will automatically inject a smart client side proxy at the @Produce annotation - an instance of the MyListener instance. When we invoke methods on this interface the method call is turned into an object and using the Camel Spring Remoting mechanism it is sent to the endpoint - in this case the ActiveMQ endpoint to queue foo; then the caller blocks for a response.

If you want to make asynchronous message sends then use an @InOnly annotation on the injection point.