Camel adviceWith behaves differently when changing the order of weave statements

Question

I have the following route for demo purposes

from("direct:external")
    .routeId("external")
    .to("http4://www.third-party.com/foo").id("ext");

For testing, I would like to * replace the http4: endpoint with a direct: endpoint * add a mock: endpoint at the end of the route for verification

I've added the following adviceWithRouteBuilder

context.getRouteDefinition("external").adviceWith(context, new AdviceWithRouteBuilder() {
    @Override
    public void configure() throws Exception {
        weaveAddLast().to("mock:result");
        weaveByToUri(".*http4://.*")
            .replace()
            .to("direct:foo");
    }
});

This one seems to work but if I change the order of the weave* statements, like so

public void configure() throws Exception {
    weaveByToUri(".*http4://.*")
        .replace()
        .to("direct:foo");
    weaveAddLast().to("mock:result");
}

It gives me the following error

java.lang.IllegalArgumentException: There are no outputs which matches: * in the route: Route(external)[[From[direct:external]] -> [pipeline -> [[To[direct:foo]]]]]

I would actually expect to get the same result, independent of the order.

Answer 1

One thing to note here is that the weave* calls are only aware of the original RouteBuilder. So when you perform the weaveByUri() call first, it replaces .to("http4://www.third-party.com/foo") with .to("direct:foo"), which incidentally happens to be the last endpoint in your route. Now, when you perform the weaveAddLast() call, it looks for "http4://www.third-party.com/foo" but doesn't find it, since it was replaced by "direct:foo". This results in an exception being thrown.

So if, hypothetically, there's another endpoint after the "http4..." endpoint such that it's not the last endpoint in your route anymore, your adviceWith() should work. For instance, it will work if your original route looked something like this:

from("direct://external")
  .routeId("external")
  .to("http4://www.third-party.com/foo")
  .id("ext")
  .to("direct://bar")
;

I should note that I think that this is a bug and that the order shouldn't matter.