Create a multiple choice route

In this workshop we will learn how to use a content based router.

We will be using Kaoto version 2.0.0 and the VS Code Kaoto extension version 0.11.0.

The suggested way of following this workshop is to read the goals of each exercise and try to do it without looking at the solution. After finishing the exercise, you can check if the solution reached is the same as the solution suggested.

If you are having difficulties with an exercise, you can try to take a look at the Hints. If that’s not enough, you can check on the Solution section how to do it.

Note that there may be more than one way of finishing the exercise.

1 - Create a choice

The goals for this exercise are:

Create a new Camel route and let it start with a timer step, which will be named tutorial
Then we set the body of the message (setBody) to a random 0 or 1 value
The third step will be a choice step with a when and an otherwise branch
- The when branch should be executed if the body of the message is 1
- The otherwise branch acts as the fallback and will automatically cover the case when the message body is 0 or actually anything else than 1
Finally we will add a log step to each of the branches
- For the 1 case we will output "We got a one!"
- For the fallback we will print the message body with "We got a ${body}"

Hints

To configure a step and fill the configuration properties, click on the step icon
You can generate random numbers using the simple expression language function random
The simple expression ${random(2)} will generate a random number between zero (included) and two (not included)
When configuring the setBody, you can use the expression language Simple and then the expression used will be ${random(2)}
We have to fill the condition ${body} == 1 in the when
We add a log step into a branch using the Insert into context menu on the when and otherwise steps
Kaoto offers two log steps to add: the camel component and the processor. For simplicity, we will choose the processor
The log has a property message which we need to fill as described in the goals

Solution

The following video showcases the solution.

At this point, the source editor should show something similar to the following code:

- route:
    id: route-1150
    from:
      id: from-2530
      uri: timer
      parameters:
        period: "1000"
        timerName: tutorial
      steps:
        - setBody:
            id: setBody-3478
            expression:
              simple:
                expression: ${random(2)}
        - choice:
            id: choice-2937
            when:
              - id: when-2316
                steps:
                  - log:
                      id: log-5995
                      message: We got a one!
                expression:
                  simple:
                    expression: ${body} == 1
            otherwise:
              id: otherwise-2904
              steps:
                - log:
                    id: log-2668
                    message: We got a ${body}

If it doesn’t look like that but you still want to go to the following exercise, you can copy and paste that code to your source editor and save the changes. This will update the design editor as well.

2 - Set Header instead of Body

In this exercise we are going to modify the previously created route to replace the setBody with a setHeader.

The goal for this exercise is:

Modify the route so instead of setting the body, we will use a header called myChoice for the decision.

Hints

To replace an existing component, right click on it and choose the Replace menu item
Watch out because there are two very similar written processors. Do not use the setHeaders processor.

Solution

The following video showcases the solution.

At this point, the source editor should show the following code:

- route:
    id: route-1150
    from:
      id: from-2530
      uri: timer
      parameters:
        period: "1000"
        timerName: tutorial
      steps:
        - setHeader:
            id: setHeader-3233
            expression:
              simple:
                expression: ${random(2)}
            name: myChoice
        - choice:
            id: choice-2937
            when:
              - id: when-2316
                steps:
                  - log:
                      id: log-5995
                      message: We got a one!
                expression:
                  simple:
                    expression: ${header.myChoice} == 1
            otherwise:
              id: otherwise-2904
              steps:
                - log:
                    id: log-2668
                    message: We got a ${body}

3 - Connect to an external service

In this exercise we are going to modify the previously created route to add calls to external APIs in the when and otherwise branches.

The goals for this exercise are:

Modify the route so when the generated random number is 0 it calls the service https://dog-api.kinduff.com/api/facts to display a random dog fact on the log
Modify the route so when the generated random number is 1 it calls the service https://cat-fact.herokuapp.com/facts/random to display a random cat fact on the log
Only use a single log at the end of the route
Change the log to just display the ${body} of the message

Note: these two services are testing services that we don’t control. Make sure they run properly before attempting to use them to prevent any weird errors.

Hints

To call an external service, you can use the https component.
You just need to configure the HTTP Uri with the proper value.
To remove a step from a flow branch, there is a - button that appears when you hover over the step.
You can add steps after the choice by clicking on the + button near it.

Solution

The following video showcases the solution.

At this point, the source editor should show the following code:

- route:
    id: route-1150
    from:
      id: from-2530
      uri: timer
      parameters:
        period: "1000"
        timerName: tutorial
      steps:
        - setHeader:
            id: setHeader-3234
            expression:
              simple:
                expression: ${random(2)}
            name: myChoice
        - choice:
            id: choice-2937
            when:
              - id: when-2316
                steps:
                  - to:
                      id: to-1376
                      uri: https
                      parameters:
                        httpUri: https://cat-fact.herokuapp.com/facts/random
                expression:
                  simple:
                    expression: ${header.myChoice} == 1
            otherwise:
              id: otherwise-2904
              steps:
                - to:
                    id: to-2860
                    uri: https
                    parameters:
                      httpUri: https://dog-api.kinduff.com/api/facts
        - log:
            id: log-2479
            message: ${body}

4 - Testing your route

So after we finished setting up our little Camel route it would be great if we could test it locally, right? Ok, then let’s do that now!

Maybe you already discovered the little buttons on the top right of the Kaoto editor. You can hover over them to know more about what they are doing. In the picture below the launch button has been marked with red coloring.

Click this button now and watch what happens. If everything goes well you should see a similar output as in the image below.

Terminal Output

If you see something different and maybe errors, please check the Hints section below.

Hints

Please make sure that you have saved your route before running it.
Make sure you installed the Extension Pack for Apache Camel as this will add buttons for easy access to launch / debug functionality. Also ensure you have installed Camel JBang , otherwise the launch will throw errors. (see Installation Guide )
This integration will work better when running it locally, as the folder must be on the same machine when it gets executed.

Solution

The following video showcases the solution.

More information

More information about Apache Camel routes can be found on the Apache Camel website