Hi all together,
during playing around with Camel I found an use case for which I like
to ask the "experts" for some advice.
I'm using Camel 2.8.0 with spring 3.0.5 on java 1.6 in a multi Camel
Context unit test scenario (one for simulating client and one for
server).
For uri's like
<to uri="bean:processor?method=process"/>
Camel usually resolves beans during creation of endpoints. This way
Camel Context from endpoint, which points to Spring application
context containing bean definition, is used. This works well.
The splitter component can use a "split method" with similar "syntax".
<split>
<method bean ="stringLineSplitter" method="split"/>
<log message="before sending: ${body}"/>
<inOut uri ="vm:route04"/>
<log message="after sending"/>
</split>
It seems that this "split bean" is resolved using Camel Context from exchange.
If I send an exchange using client Camel Context, please remember I'm
using two Camel Contexts, to a route defined in server Camel Context
using in-memory transport like "direct" or "vm"
<route id="route02" trace="false" streamCache="false">
<from uri="vm:route02"/>
<split>
<method bean ="stringLineSplitter" method="split"/>
<log message="before sending: ${body}"/>
<inOut uri ="vm:route04"/>
<log message="after sending"/>
</split>
<to uri="mock:route02"/>
</route>
the test fails with "Cannot find class: stringLineSplitter" thrown
from a class "ObjectHelper". If I understood Camel right it fails
because it tries to resolve this bean based on client Camel Context
which is still set at the exchange send from client to server but
doesn't contain the bean.
If I send an exchange using same client Camel Context to a route in
server Camel Context involving "external" components like "jms"
(ActiveMQ)
<route id="route03" trace="false" streamCache="false">
<from uri="jms:queue:route03"/>
<split>
<method bean ="stringLineSplitter" method="split"/>
<log message="before sending: ${body}"/>
<inOut uri ="vm:route04"/>
<log message="after sending"/>
</split>
<to uri="mock:route03"/>
</route>
the test passed successfully. It seems that "jms" component creates a
new exchange but "vm" reuses the one from internal queue.
After diving into the code I found a place to adjust this behavior.
Changing one line in the else-clause of
class org.apache.camel.model.language.MethodCallExpression
method
createExpression( CamelContext camelContext ) : Expression
from
answer = new BeanExpression( ref1, getMethod() );
to
answer = new BeanExpression( this.instance, getMethod() );
did the trick (means: now all my tests passed successfully).
In the code lines before the bean holder was already created but in
original version not used.
Now my questions:
1. Is it right to expect that both use cases should behave similar?
2. Shouldn't every component create a new exchange during
receiving/consuming, minimally re-set Camel Context if it crosses
borders?
3, Is the proposed change correct or will it produce (unwanted) side effects?
4. If change is ok could it be part of Camel?
Any help/comment/hint are highly welcome.
Best Regards
Bernd
