[CONF] Apache Camel: StringTemplate (page edited)

Thu, 05 Jun 2008 21:46:37 -0700

Page Edited : CAMEL : StringTemplate

StringTemplate has been edited by Claus Ibsen (Jun 05, 2008).

(View changes)

Content:

String Template

The string-template: component allows you to process a message using a String Template. This can be ideal when using Templating to generate responses for requests.

URI format

string-template:templateName

Where templateName is the classpath-local URI of the template to invoke; or the complete URL of the remote template.



Options






 Option 
 Default 
 Description 




 contentCache 
 false 
 New option in Camel 1.4. Cache for the resource content when its loaded. 






Headers


Camel will store a reference to the resource in the message header in the key org.apache.camel.stringtemplate.resource. The Resource is an org.springframework.core.io.Resource object.



Hot reloading


The stringtemplate resource is by default hot reloadable for both file and classpath resources (expanded jar). Setting the contentCache=true then Camel will only load the resource once, and thus hot reloading is not possible. This scenario can be used in production usage when the resource never changes.



Velocity Content


Camel will provide exchange information in the velocity context (just a Map). The Exchange is transfered to the VelocityContext as:





 key 
 value 




 exchange 
 The Exchange itself 




 headers 
 The headers of the in message 




 camelContext 
 The Camel Context 




 request 
 The in message 




 in 
 The in message 




 body 
 The in message body




 out 
 The out message (only for InOut message exchange pattern) 




 response 
 The out message (only for InOut message exchange pattern) 






Samples



For example you could use something like





from("activemq:My.Queue").
  to("string-template:com/acme/MyResponse.tm");





To use a string template to formulate a response for a message



The Email Sample


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




Dear $headers.lastName$, $headers.firstName$

Thanks for the order of $headers.item$.

Regards Camel Riders Bookstore





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");
    return exchange;
}

public void testVelocityLetter() 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");

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

    mock.assertIsSatisfied();
}

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





See Also

Powered by Atlassian Confluence (Version: 2.2.9 Build:#527 Sep 07, 2006) - Bug/feature request

Unsubscribe or edit your notifications preferences

Reply via email to