[CONF] Apache Camel: Bean (page edited)

confluence Mon, 10 Nov 2008 04:47:33 -0800

Page Edited : CAMEL : Bean

Bean has been edited by Claus Ibsen (Nov 10, 2008).

Change summary:

CAMEL-656

(View changes)

Content:

Bean Component

The bean: component binds beans to Camel message exchanges.

URI format

bean:someName[?options]

Where someName can be any string which is used to lookup the bean in the Registry

Options

Name	Type	Default	Description
method	String	null	The method name that bean will be invoked. If not provided Camel will try to pick the method itself. In case of ambiguity an exception is thrown. See Bean Binding for more details.
cache	boolean	false	If enabled Camel will cache the result of the first Registry lookup. Cache can be enabled if the bean in the Registry is defined as a singleton scope.
multiParameterArray	boolean	false	Camel 1.5: How to treat the parameters which are passed from the message body, if it is true, the in message body should be the an array of parameters.

Using

The object instance that is used to consume messages must be explicitly registered with the Registry. For example if you are using Spring you must define the bean in the spring.xml; or if you don't use Spring then put the bean in JNDI.

// lets populate the context with the services we need
// note that we could just use a spring.xml file to avoid this step
JndiContext context = new JndiContext();
context.bind("bye", new SayService("Good Bye!"));

CamelContext camelContext = new DefaultCamelContext(context);

Once an endpoint has been registered, you can build Camel routes that use it to process exchanges.

// lets add simple route
camelContext.addRoutes(new RouteBuilder() {
    public void configure() {
        from("direct:hello").to("pojo:bye");
    }
});

A bean: endpoint cannot be defined as the input to the route; i.e. you cannot consume from it, you can only route from some inbound message Endpoint to the bean endpoint as output. So consider using a direct: or queue: endpoint as the input.

You can use the createProxy() methods on ProxyHelper to create a proxy that will generate BeanExchanges and send them to any endpoint:

Endpoint endpoint = camelContext.getEndpoint("direct:hello");
ISay proxy = ProxyHelper.createProxy(endpoint, ISay.class);
String rc = proxy.say();
assertEquals("Good Bye!", rc);

And the same route using Spring DSL:

<route>
       <from uri="direct:hello">
       <to uri="bean:bye"/>
    </route>

Bean as endpoint

Camel also supports invoking Bean as an Endpoint. In the route below:

What happens is that when the exchange is routed to the myBean Camel will use the Bean Binding to invoke the bean.
The source for the bean is just a plain POJO:

Camel will use Bean Binding to invoke the sayHello method, by converting the Exchange IN body to the String type and store the output of the method on the Exchange OUT body.

Bean Binding

How bean methods are chosen to be invoked (if they are not specified explicitly via the method parameter) and how parameter values are constructed from the Message are all defined by the Bean Binding mechanism which is used througout all of the various Bean Integration mechanisms in Camel.