I am not so sure about that. I had the same thoughts more than a year
ago, but I came to the conclusion that it's best the way it is,
although a bit confusing at times for the beginner.
A bit of background on this. Initially Camel did not have explicit
Block processors. A Block processor is a chain of processor that sort
of act like one. Like a choice() for instance. In the case of a
choice() for instance, one could not continue processing after the
choice(), regardless of what path in the choice(). The route ends
implicitly after the last processor, but in the choice() case for
instance meant that whatever came after otherwise() was the processing
for the otherwise() path, and hence still part of choice(). And
that's how the Block processor came to be. For a Block processor such
as choice() when end() is encountered it indicates the end of the
otherwise() (or last when() if no otherwise()) and whatever follows
end() will continue the processing regardless what path of choice()
was chosen.
Now there was the question of explicit end() for Block processors. In
xml there is no problem, as you pointed out. In Java we had to decide
to either enforce explicit end() or support and implicit, silent end()
if there was a block processor, which was the case previously. For
backward compatibility and not to clutter the routes in simpler cases,
we decided the the latter is the better (although not ideal) solution.
Coming back to the original example, it does not need and end() as
there is no Block processor there. A route ends simply by not having
another processor to send the message to.
My $0.02,
Hadrian
On Jun 10, 2009, at 7:55 AM, Claus Ibsen wrote:
On Wed, Jun 10, 2009 at 1:46 PM, Roman
Kalukiewicz<[email protected]> wrote:
BTW The message in the Exception could be more clear. It is not
obvious what "Root node with no active block" is ;)
Yeah I have been wondering if we should force a begin DSL for the few
EIP types that have nested routes,
to easier pair begin / end and have better errors if missing.
In Spring XML you have the XML tags start/end tag for that. So that is
really an area where the XML is better than Java DSL.
Roman
2009/6/10 Claus Ibsen <[email protected]>:
On Wed, Jun 10, 2009 at 1:09 PM, Peter Maas<[email protected]>
wrote:
Hi,
I wondered what the purpose of the 'end' method in a route is. I
sort of
expected it to be a terminator for dead-end routes. But that
doesn't seem to
be the case.
If I do something like this:
from("direct:start")
.process(new Processor(){
public void process(Exchange arg0) throws
Exception {
System.out.println("hello!");
}
})
.end();
I get the following exception:
java.lang.IllegalArgumentException: Root node with no active block
at
org
.apache
.camel.model.ProcessorDefinition.end(ProcessorDefinition.java:719)
I currently 'terminate' such a route by using a non-existent direct
endpoint, which works but raises a WARN messages...
What is the preferred way to do this?
Not to use end() at all.
They should only be used for some special EIP that kinda have sub
routes, such as
- aggregator
- splitter
and a few others
So your route should just be:
from("direct:start")
.process(new Processor(){
public void process(Exchange arg0) throws Exception {
System.out.println("hello!");
}
});
-P
--
Claus Ibsen
Apache Camel Committer
Open Source Integration: http://fusesource.com
Blog: http://davsclaus.blogspot.com/
Twitter: http://twitter.com/davsclaus
--
Claus Ibsen
Apache Camel Committer
Open Source Integration: http://fusesource.com
Blog: http://davsclaus.blogspot.com/
Twitter: http://twitter.com/davsclaus
