Writing Integrations in YAML

The YAML DSL is current in preview support level.

Defining a route

A route is a sequence of elements, or steps, defined as follow:

from: (1)
  uri: "direct:start"
  steps: (2)
    - filter:
          simple: "${in.header.continue} == true"
        steps: (2)
          - to:
              uri: "log:filtered"
    - to:
        uri: "log:original"
1 route entry point, by default from and rest are supported
2 processing steps

Each step is represented by YAML map that has a single entry where the field name is the EIP name

As general rule each step provide all the parameters the related definition declares but there are some minor differences/enhancements:

  • Output Aware Steps

    Some steps such as filter and split have their own pipeline when an exchange matches the filter expression or for the items generated by the split expression, such pipeline can be defined by the steps field:

        simple: "${in.header.continue} == true"
            - to:
                uri: "log:filtered"

    if the steps field is omitted, then each subsequent step is considered part of the filter pipeline.

  • Expression Aware Steps

    Some EIP such as filter and split supports the definition of an expression through the expression field:

    Explicit Expression field
          simple: "${in.header.continue} == true"

    To make the DSL less verbose, the expression field can be omitted:

    Implicit Expression field
        simple: "${in.header.continue} == true"

    In general expression can be defined inline like in the examples above but in case you need provide more information, you can 'unroll' the expression definition and configure any single parameter the expression defines.

    Full Expression definition
          token: "<"
          end-token: ">"
  • Data Format Aware Steps

    Some EIP such as set-body and marshal supports the definition of data formats through the data-format field:

    Explicit Data Format field
            library: Gson

    To make the DSL less verbose, the data-format field can be omitted:

    Implicit Data Format field
          library: Gson

    In case you want to use the data-format’s default settings, you need to place an empty block as data format parameters, like json: {}

Extending the DSL

The DSL is designed to be easily extended so you can provide your own step handler which is discovered at runtime using Camel’s factory finder.

Assuming you want to create a step to simplify the creation of a certain type of endpoints then you need:

  • create a service definition entry in META-INF/services/org/apache/camel/k/yaml with content like:

  • create the step handler extending org.apache.camel.k.loader.yaml.parser.ProcessorStepParser

    package com.acme.converter.AcmeConverter
    import org.apache.camel.k.loader.yaml.parser.ProcessorStepParser;
    public class AcmeConverter
            implements ProcessorStepParser {
         * @param context contains a references to the camel context and the current node as raw JsonNode
        public ProcessorDefinition<?> toProcessor(Context context) {
            // decode the raw json node
            Definition definition = context.node(Definition.class);
            // create the definition
            ToDefinition to = new ToDefinition()
            to.setUri(String.format("http://%s:%d/fixed/path"), definition.host, definition.port)
            return to;
         * Define the data
        public static final class Definition {
            public String host;
            @JsonSetter(nulls = Nulls.SKIP)
            public Integer port = 8080;

Assuming the entry in the META-INF/services/org/apache/camel/k/yaml is named acme then you can use it from the YAML DSL like:

  uri: "direct:start"
    - acme:
        host: acme.com
        port: 8081

Supported EIP

  • Aggregate

  • Bean

  • Choice

  • Circuit Breaker

  • Claim Check

  • Convert Body To

  • Delay

  • Dynamic Router

  • Enrich

  • Filter

  • From

  • Idempotent Consumer

  • Load Balance

  • Log

  • Loop

  • Marshal

  • Multicast

  • Pipeline

  • PollEnrich

  • Process

  • Recipient List

  • Remove Header

  • Remove Headers

  • Remove Property

  • Remove Properties

  • Resequence

  • Rest DSL

  • Rollback

  • Routing Slip

  • Saga

  • Sample

  • Script

  • ServiceCall

  • Set Body

  • Set Exchange Pattern

  • Set Header

  • Set Property

  • Sort

  • Split

  • Step

  • Stop

  • Threads

  • Throttle

  • Throw Exception

  • To

  • To Dynamic

  • Transacted

  • Transform

  • Try Catch Finally

  • Unmarshal

  • Validate

  • Wire Tap

The Try Catch Finally EIP currently only support specifying one do-catch clause.