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 2 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

outputs

Required

List

disabled

Whether to disable this EIP from the route during build time. Once an EIP has been disabled then it cannot be enabled later at runtime.

false

Boolean

description

Sets the description of this node.

String

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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