Available as of FUSE Mediation Router 1.6

The freemarker: component allows you to process a message using a Freemarker template. This can be ideal when using Templating to generate responses for requests.

freemarker:templateName

Where templateName is the classpath-local URI of the template to invoke; or the complete URL of the remote template (eg: file://folder/myfile.ftl).

FUSE Mediation Router will store a reference to the resource in the message header in the key org.apache.camel.freemarker.resource. The Resource is an org.springframework.core.io.Resource object. And the key org.apache.camel.freemarker.resourceUri holds the templateName as a String object.

Headers set during the Freemarker evaluation is returned to the message and added as headers. Then its kinda possible to return values from Freemarker to the Message.

An example: Set the header value of fruit in the Freemarker template:

${request.setHeader('fruit', 'Apple')}

The header 'fruit' is now accessible from the message.out.headers.

FUSE Mediation Router will provide exchange information in the Freemarker context (just a Map). The Exchange is transfered as:

The Freemarker template resource is by default not hot reloadable for both file and classpath resources (expanded jar). Setting the contentCache=false then FUSE Mediation Router will not cache the resource and hot reloading is thus enabled. This scenario can be used in development usage.

For example you could use something like

from("activemq:My.Queue").
  to("freemarker:com/acme/MyResponse.ftl");

To use a Freemarker template to formulate a response for a message for InOut message exchanges (where there is a JMSReplyTo header).

If you want to use InOnly and consume the message and send it to another destination you could use

from("activemq:My.Queue").
  to("freemarker:com/acme/MyResponse.ftl").
  to("activemq:Another.Queue");

And to disable the content cache, eg. for development usage where the .ftl template should be hot reloaded:

from("activemq:My.Queue").
  to("freemarker:com/acme/MyResponse.ftl?contentCache=false").
  to("activemq:Another.Queue");

And a file based resource:

from("activemq:My.Queue").
  to("freemarker:file://myfolder/MyResponse.ftl?contentCache=false").
  to("activemq:Another.Queue");

In this sample we want to use Freemarker as templating for an order confirmation email. The email template is laid out in Freemarker as:

Dear ${headers.lastName}, ${headers.firstName}

Thanks for the order of ${headers.item}.

Regards Camel Riders Bookstore
${body}

And the java code:

private Exchange createLetter() {
    Exchange exchange = context.getEndpoint("direct:a").createExchange();
    Message msg = exchange.getIn();
    msg.setHeader("firstName", "Claus");
    msg.setHeader("lastName", "Ibsen");
    msg.setHeader("item", "Camel in Action");
    msg.setBody("PS: Next beer is on me, James");
    return exchange;
}

public void testFreemarkerLetter() throws Exception {
    MockEndpoint mock = getMockEndpoint("mock:result");
    mock.expectedMessageCount(1);
    mock.expectedBodiesReceived("Dear Ibsen, Claus\n\nThanks for the order of Camel in Action.\n\nRegards Camel Riders Bookstore\nPS: Next beer is on me, James");

    template.send("direct:a", createLetter());

    mock.assertIsSatisfied();
}

protected RouteBuilder createRouteBuilder() throws Exception {
    return new RouteBuilder() {
        public void configure() throws Exception {
            from("direct:a").to("freemarker:org/apache/camel/component/freemarker/letter.ftl").to("mock:result");
        }
    };
}