Chunk

Since Camel 2.15

The chunk: component allows for processing a message using a Chunk template. This can be ideal when using Templating to generate responses for requests.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-chunk</artifactId>
<version>x.x.x</version> <!-- use the same version as your Camel core version -->
</dependency>

URI format

chunk:templateName[?options]

Where templateName is the classpath-local URI of the template to invoke.

You can append query options to the URI in the following format, ?option=value&option=value&…​

Options

The Chunk component has no options.

The Chunk endpoint is configured using URI syntax:

chunk:resourceUri

with the following path and query parameters:

Path Parameters (1 parameters):

Name Description Default Type

resourceUri

Required Path to the resource. You can prefix with: classpath, file, http, ref, or bean. classpath, file and http loads the resource using these protocols (classpath is default). ref will lookup the resource in the registry. bean will call a method on a bean to be used as the resource. For bean you can specify the method name after dot, eg bean:myBean.myMethod.

String

Query Parameters (7 parameters):

Name Description Default Type

contentCache (producer)

Sets whether to use resource content cache or not

false

boolean

encoding (producer)

Define the encoding of the body

String

extension (producer)

Define the file extension of the template

String

themeFolder (producer)

Define the themes folder to scan

String

themeLayer (producer)

Define the theme layer to elaborate

String

themeSubfolder (producer)

Define the themes subfolder to scan

String

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-chunk-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 2 options, which are listed below.

Name Description Default Type

camel.component.chunk.enabled

Enable chunk component

true

Boolean

camel.component.chunk.resolve-property-placeholders

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

Boolean

Chunk component will look for a specific template in themes folder with extensions .chtml or _.cxml. _If you need to specify a different folder or extensions, you will need to use the specific options listed above.

Chunk Context

Camel will provide exchange information in the Chunk context (just a Map). The Exchange is transferred as:

key value

exchange

The Exchange itself.

exchange.properties

The Exchange properties.

headers

The headers of the In message.

camelContext

The Camel Context.

request

The In message.

body

The In message body.

response

The Out message (only for InOut message exchange pattern).

Dynamic templates

Camel provides two headers by which you can define a different resource location for a template or the template content itself. If any of these headers is set then Camel uses this over the endpoint configured resource. This allows you to provide a dynamic template at runtime.

Header Type Description Support Version

ChunkConstants.CHUNK_RESOURCE_URI

String

A URI for the template resource to use instead of the endpoint configured.

ChunkConstants.CHUNK_TEMPLATE

String

The template to use instead of the endpoint configured.

Samples

For example you could use something like:

from("activemq:My.Queue").
to("chunk:template");

To use a Chunk 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("chunk:template").
to("activemq:Another.Queue");

It’s possible to specify what template the component should use dynamically via a header, so for example:

from("direct:in").
setHeader(ChunkConstants.CHUNK_RESOURCE_URI).constant("template").
to("chunk:dummy");

An example of Chunk component options use:

from("direct:in").
to("chunk:file_example?themeFolder=template&themeSubfolder=subfolder&extension=chunk");

In this example Chunk component will look for the file file_example.chunk in the folder template/subfolder.

The Email Sample

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

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

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

Regards Camel Riders Bookstore
{$body}
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