components/camel-chunk/src/main/docs/chunk-component.adoc

## Chunk Component

*Available as of Camel version 2.15*

The *chunk:* component allows for processing a message using a
http://www.x5software.com/chunk/examples/ChunkExample?loc=en_US[Chunk] template.
This can be ideal when using link:templating.html[Templating] to
generate responses for requests.

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

[source,xml]
---------------------------------------------------------------------------------
<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

[source,java]
----------------------------
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


// component options: START
The Chunk component has no options.
// component options: END



// endpoint options: START
The Chunk endpoint is configured using URI syntax:

    chunk:resourceUri

with the following path and query parameters:

#### Path Parameters (1 parameters):

[width="100%",cols="2,5,^1,2",options="header"]
|=======================================================================
| 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):

[width="100%",cols="2,5,^1,2",options="header"]
|=======================================================================
| 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
|=======================================================================
// endpoint options: END


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:

 
[width="100%",cols="20%,80%",options="header",]
|=======================================================================
|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.

[width="100%",cols="20%,10%,10%,60%",options="header",]
|=======================================================================
|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:

[source,java]
--------------------------
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:

[source,java]
-----------------------------
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:

[source,java]
------------------------------------------------------------------
from("direct:in").
setHeader(ChunkConstants.CHUNK_RESOURCE_URI).constant("template").
to("chunk:dummy");
------------------------------------------------------------------

An example of Chunk component options use:

[source,java]
---------------------------------------------------------------------------------------
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:

[source,java]
----------------------------------------------
 
Dear {$headers.lastName}, {$headers.firstName}

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

Regards Camel Riders Bookstore
{$body}
----------------------------------------------

### See Also

* link:configuring-camel.html[Configuring Camel]
* link:component.html[Component]
* link:endpoint.html[Endpoint]
* link:getting-started.html[Getting Started]