Apache Camel Route doesn't set body

I have two Apache Camel Routers in a Docker Network.

The one acts as client and sends some data in the body to the outer with a route.

I now want to get the modified body from the server router.

But apparently the body modification is never applied.

(For context the initial request is a post request where the final body should be the response)

Here is how my "client" route looks like:

<camelContext xmlns="http://camel.apache.org/schema/blueprint">

<restConfiguration component="restlet" bindingMode="json" port="8989" enableCORS="true"/>

<rest path="/finData">
  <description>User rest service</description>
  <post>
    <to uri="direct:update"/>
  </post>
</rest>

<route id="sendFinData">
  <from uri="direct:update"/>
  <log message="Got some data:  ${body}"/>
  <to uri="aclient://otherClient:9191"/>
</route>

And here is how the "server" looks like:

 <camelContext xmlns="http://camel.apache.org/schema/blueprint">


 <route id="receiveFinData">
  <from
    uri="aserver://0.0.0.0:9191"/>
  <log message="Received via data: ${body}"/>
  <setBody>
    <simple>{"result": true }</simple>
  </setBody>
</route>

Update: If I add a second route to the "client" and call this one instead the external of the "server" and modify the body there it is working

Solution

Update due to comments: When the setBody is not the problem, then I have to ask about the flow in the code.

Are you calling /finData to send a request from the client to the server?
But who is listening on aclient://otherClient:9191? This route is not in your question.
And the caller of aserver://0.0.0.0:9191 is also not in your question.

Can you post the whole flow?

Original answer

I think @tadayoshi-sato already commented the solution to your problem.

You use the Camel Simple language (an Expression Language) to set a constant string into your message body.

Use the Camel Constant language instead.

<setBody>
    <constant>{"result": true }</constant>
</setBody>