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Camel supports the integration of beans with Camel message exchanges in a number of ways.
Bean Component
The Bean component supports the creation of a proxy via ProxyHelper to a Java interface; which the implementation just sends a message containing a BeanInvocation to some Camel endpoint.
Then there is a server side implementation which consumes a message and uses the Bean Binding to bind the message to invoke a method passing in its parameters.
Bean Post Processor
Annotations
If a bean is defined in Spring XML and it has some Camel annotations then it can be processed to inject resources.
Sending messages
To allow sending of messages you can use @EndpointInject() annotation. This will inject either a ProducerTemplate or CamelTemplate so that the bean can send message exchanges.
e.g. lets send a message to the foo.bar queue in ActiveMQ at some point
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public class Foo {
@EndpointInject(uri="activemq:foo.bar")
ProducerTemplate producer;
public void doSomething() {
if (whatever) {
producer.sendBody("<hello>world!</hello>");
}
}
}
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Consuming messages
To consume a message you use a @MessageDriven annotation to mark a particular method of a bean as being a consumer method. The uri of the annotation defines the Camel Endpoint to consume from. The Bean Binding is then used to convert the inbound Message to the parameter list used to invoke the method
e.g. lets invoke the onCheese() method with the String body of the inbound JMS message from ActiveMQ on the cheese queue; this will use the Type Converter to convert the JMS ObjectMessage or BytesMessage to a String - or just use a TextMessage from JMS
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or scanned using the Spring 2.5 component scanning mechanism and a <camelContext> is used or a CamelBeanPostProcessor then we process a number of Camel annotations to do various things such as injecting resources or producing, consuming or routing messages.
- Bean Injection to inject Camel related resources into your POJOs
- POJO Consuming to consume and possibly route messages from Camel
- POJO Producing to make it easy to produce camel messages from your POJOs
- RecipientList Annotation for creating a Recipient List from a POJO method
- Using Exchange Pattern Annotations describes how the pattern annotations can be used to change the behaviour of method invocations with Spring Remoting or POJO Producing
Spring Remoting
We support a Spring Remoting provider which uses Camel as the underlying transport mechanism. The nice thing about this approach is we can use any of the Camel transport Components to communicate between beans. It also means we can use Content Based Router and the other Enterprise Integration Patterns in between the beans; in particular we can use Message Translator to be able to convert what the on-the-wire messages look like in addition to adding various headers and so forth.
Bean Component
The Bean component supports the creation of a proxy via ProxyHelper to a Java interface; which the implementation just sends a message containing a BeanInvocation to some Camel endpoint.
Then there is a server side implementation which consumes a message and uses the Bean Binding to bind the message to invoke a method passing in its parameters.
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