Kamelet

Kamelets (Kamel route snippets) allow users to connect to external systems via a simplified interface, hiding all the low level details about how those connections are implemented.

By default, calling kamelets should be done as endpoints with the kamelet component, such as to("kamelet:mykamelet").

The Kamelet EIP allows calling Kamelets (i.e. Route Template), for special use-cases.

When a Kamelet is designed for a special use-case such as aggregating messages, and returning a response message only when a group of aggregated message is completed. In other words the kamelet does not return a response message for every incoming message. In special situations like these, then you must use this Kamelet EIP instead of using the kamelet component.

Given the following Kamelet (as a route template):

routeTemplate("my-aggregate")
        .templateParameter("count")
        .from("kamelet:source")
        .aggregate(constant(true))
            .completionSize("{{count}}")
            .aggregationStrategy(AggregationStrategies.string(","))
            .to("log:aggregate")
            .to("kamelet:sink")
        .end();
Note how the route template above uses kamelet:sink as a special endpoint to send out a result message. This is only done when the Aggregate EIP has completed a group of messages.

And the following route using the kamelet:

from("direct:start")
    // this is not possible, you must use Kamelet EIP instead
    .to("kamelet:my-aggregate?count=5")
    .to("log:info")
    .to("mock:result");

Then this does not work, instead you must use Kamelet EIP instead:

from("direct:start")
    .kamelet("my-aggregate?count=5")
    .to("log:info")
    .to("mock:result");

When calling a Kamelet you may just refer to the name (template id) of the Kamelet in the EIP as shown below:

Options

The Kamelet eip supports 1 options, which are listed below.

Name Description Default Type

name

Required Name of the Kamelet (templateId/routeId) to call. Options for the kamelet can be specified using uri syntax, eg mynamecount=4&type=gold.

String

description

Sets the description of this node.

DescriptionDefinition

Using Kamelet EIP

from("direct:start")
    .kamelet("foo")
    .to("mock:result");

And in XML

<route>
    <from uri="direct:start"/>
    <kamelet name="foo"/>
    <to uri="mock:result"/>
</route>

Camel will then, when starting:

  • Lookup the Route Template with the given id (in the example above its foo) from the CamelContext

  • Create a new route based on the Route Template

Dependency

The implementation of the Kamelet EIP is located in the camel-kamelet JAR, so you should add the following dependency:

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

See Also

See the example camel-example-kamelet.

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