Spring integration enrichHeaders

Question

I have a header "BackOffTime". I need to update it, but using another header "failCount".

Like this:

Long backOff = Math.pow(2, headers.get("failCount"));

enricherSpec.headerExpression("BackOffTime", backOff, true);

But problem is, that method enrichHeaders() doesn't have lambda with (message, headers) ->

so I can't get value from "failCount" header.

Is there a way to do it like this?:

.enrichHeaders(enricherSpec -> {
                    Long backOff = Math.pow(2, headers.get("failCount"));
                    enricherSpec.headerExpression("BackOffTime", backOff, true);
                })

I found one way to get header, but it only allows to get it, but not use it in any function:

enricherSpec.headerExpression("BackOffTime", "headers['failCount']", true);

Answer 1

Consider to do something like this:

.enrichHeaders(h -> h.headerFunction("BackOffTime", m -> Math.pow(2, m.getHeaders().get("failCount", Double.class)), true))

The top-level Consumer<HeaderEnricherSpec> lambda is called only once and only during configuration phase. What you need is a function call per message. Therefore it has to be an option on that HeaderEnricherSpec already. And in our case it is a headerFunction(). It also can be done with the headerExpression(), but I find the Java syntax more convenient for DSL.