AOP
Available as of Camel 2.0
Camel has a AOP concept in the DSL allowing you do do some custom before and/or after processing when routing an Exchange.
It replaces the intercept from Camel 1.x that was more limited as it could was a fix around a single processor.
This new AOP can span multiple processors (nodes in the route graph) and it uses endpoint URIs to allow invoking any kind of Camel component.
The AOP supports the following callbacks in which you can use 1..n free of choice:
- before
- after
- afterFinally
The difference between after and afterFinally is that afterFinally is invoked from a finally block so it will always be invoked no matter what, eg also in case of an exception occur.
Using from Java DSL
In this route we want to use the AOP to do a before and after logging.
from("jms:queue:inbox")
.aop().around("log:before", "log:after")
.to("bean:order?method=validate")
.to("bean:order?method=handle")
.end()
.to("jms:queue:order");
Notice that we use the end to indicate where the AOP around should end, for instance if we do more routing afterwards such as sending to another JMS queue. In the route below the AOP is only being around the bean processing.
The aop in Java DSL have the following methods:
- around
- aroundFinally
- before
- after
- afterFinally
Using from Spring DSL
In Spring DSL its nearly the same as in the Java DSL however a bit differently
<route>
<from uri="jms:queue:inbox"/>
<aop beforeUri="log:before" afterUri="log:after">
<to uri="bean:order?method=validate"/>
<to uri="bean:order?method=handle"/>
</aop>
<to uri="jms:queue:order"/>
Notice we use attributes on the <aop> tag to chose with AOP concept to use.
The aop in Spring DSL have the following attributes:
- beforeUri
- afterUri
- afterFinallyUri
So in order to do an around we use both the beforeUri and the afterUri.