Converting Java DSL to Spring XML equivalent

Question

So this may be a more general question, but I feel it needs to be asked.

Time and time again I come across examples on Camel's documentation pages where I say "that's exactly what I want!... but it's in Java not Spring. How the heck do I convert it properly?"

So my question is: What is the rule of thumb for converting things?

Is there some conversion guide out there?

For example, I wanted to append a \n to the end of each line as the data comes through a socket into a file using the Netty4 component.

I see an example such as .transform().body(append("\n"))

How would I interpret that as Spring, to put in my Spring-based route?

Maybe this is just a thing that a person new to Camel struggles with and once you get the hang of it you can see the obvious answer. But I feel like I can't be the only one who's thinking this about the examples out there.

It seems like a lot of Java -> Spring conversion can be done in a 1 to 1 ratio, but that's not all the time.

Answer 1

Well, the mapping isn't straightforward and there isn't a 1-to-1 mapping available - generally, a Java DSL method invocation will in most cases translate to a tag in Spring XML DSL but the position of that tag is not always the same - in some cases Java DSL method invocation chains translate to tags being placed on the same level, sometimes (e.g. idempotent consumer) the chain translates to child tags of the first invocation.

I guess that the mapping was done this way because XML and Java are two very different languages and making the mapping 1-1 would have crippled the expressiveness of at least one, if not both, DSLs.

My advice would be to always import the XML schema and rely on your IDE's auto-completion and the documentations from the schema itself and Camel's online documentation.

Answer 2

You can run your camel context via mvn camel:run goal and then use a JMX client to connect to that process. There is an mbean in camel which provides a method called dumpRoutesAsXML or similar. Invoking that one will give u the xml equivalent of your context. But keep in mind that it only prints the routes and all stuff out of routes is discarded.

Hope that helps, Lars