[[chunk-component]]
== 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 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 supports 2 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *resolveProperty Placeholders* (advanced) | Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. | true | boolean
| *basicPropertyBinding* (advanced) | Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | boolean
|===
// 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 (9 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
| *lazyStartProducer* (producer) | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean
| *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
| *basicPropertyBinding* (advanced) | Whether the endpoint should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | boolean
| *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
// spring-boot-auto-configure options: START
=== Spring Boot Auto-Configuration

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

[source,xml]
----
<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 3 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *camel.component.chunk.basic-property-binding* | Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | Boolean
| *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
|===
// spring-boot-auto-configure 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

* Configuring Camel
* Component
* Endpoint
* Getting Started
