How to use a custom response body?

You need to define a custom ResponseWritable[T] for your type T.

Let's say you have a MyXML class, and you want to use it as a response body.
You would write something like this:

given ResponseWritable[MyXML] with {
  override def write(value: MyXML, exchange: HttpServerExchange): Unit =
    exchange.getResponseSender.send(value.asString)
  override def headers(value: String): Seq[(HttpString, Seq[String])] = Seq(
    HttpString(HeaderNames.ContentType) -> Seq("text/xml")
  )
}

Now you can use MyXML as a response body:

val myXml = MyXML(...)
Response.withBody(myXml)