My question is very similar to this one but the solution there does not work for me here - I am trying to use the filter EIP to discard selected exchanges. My routes look like (edited down for clarity):
from("{{fromSource}}")
.convertBodyTo(RequestInterface.class)
.enrich(INVOKE_BACKEND_URI, combiner)
.to("{{toDestination}}");
from(INVOKE_BACKEND_URI)
.to(backendUri)
.filter().method(DiscardResponse.class).log(LoggingLevel.INFO, "Discarding undesired response").stop().end()
.convertBodyTo(BodyInterface.class);
When the filter does NOT select the message, all is well - the log() is not displayed and the message goes to the convertBodyTo() and then back to the main route.
However, when the filter DOES select the message, the log() text is displayed but the exchange still continues on to the convertBodyTo() where it throws an exception because it's a message that shouldn't be there. The stop() appears to either not be executed or has no affect.
Can anyone suggest a solution to this?
It is possible from within a Processor to do this in order to stop the exchange:
exchange.setProperty(Exchange.ROUTE_STOP, Boolean.TRUE);
Since I'm not used to writing my routes using Java DSL I don't know if that option is available directly on the exchange within the route, but it probably is.
I guess one way could be:
from(INVOKE_BACKEND_URI)
.to(backendUri)
.filter().method(DiscardResponse.class).log(LoggingLevel.INFO, "Discarding undesired response")
.choice()
.when(simple("${property.Exchange.FILTER_MATCHED}=true")
.stop()
.end()
.convertBodyTo(BodyInterface.class);
Take a look at the bottom of the doc here:
http://camel.apache.org/message-filter.html
Related
I have this simple route in my RouteBuilder.
from("amq:MyQueue").routeId(routeId).log(LoggingLevel.DEBUG, "Log: ${in.headers} - ${in.body}")
As stated in the doc for HTTP-component:
Camel will store the HTTP response from the external server on the OUT body. All headers from the IN message will be copied to the OUT message, ...
I would like to know if this concept also applies to amq-component, routeId, and log? Is it the default behaviour, that IN always gets copied to OUT?
Thank you,
Hadi
First of all: The concept of IN and OUT messages is deprecated in Camel 3.x.
This is mentioned in the Camel 3 migration guide and also annotated on the getOut method of the Camel Exchange.
However, it is not (yet) removed, but what you can take from it: don't care about the OUT message. Use the getMessage method and don't use getIn and getOut anymore.
To answer your question:
Yes, most components behave like this
Every step in the route takes the (IN) message and processes it
The body is typically overwritten with the new processing result
The headers typically stay, new headers can be added
So while the Camel Exchange traverses the route, typically the body is continuously updated and the header list grows.
However, some components like aggregator create new messages based on an AggregationStrategy. In such cases nothing is copied automatically and you have to implement the strategy to your needs.
After using recipientList in a camel route, within a choice.when, I would like to route this further to another destination with to("xy").
Syntax-highlighting in a java IDE is showing me that this is not possible.
If I put an end after recipientList, all appears to fit again.
Is that required? I could not find any examples in the docs/net showing s/t similar...
.choice()
.when(aPredicate)
.setHeader(Exchange.FILE_NAME).simple("st")
.recipientList(getAValueBuilder())
.end()
.to("ftp:me#ftpserv//usr/dest")
.when(anotherPredicate)
.to(nirv)
.setHeader(Exchange.FILE_NAME).simple("nt")
.to("ftp:me#ftpserv//usr/anotherdest")
.end()
Generarilly I am not sure, while using choice, when to use end. And to make it more difficult, there is an endChoice...
I tryed to use the formatting, to show the way I think it should be use above.
Thanks for feedback.
I'm using Apache Camel, and trying to create a log of the history of the processing of each message in a workflow.
For simple straight-through workflows, where a message comes in, is processed by a few steps, and then leaves, this could be as simple as just keeping a sequential log of the exchanges. I can do this by writing a custom TraceEventHandler, which is called at each exchange and allows me to do logging.
However, if a splitter is involved, I don't know how to calculate the provenance of any given exchange. I could maintain my own log of exchanges, but in the case of a splitter, not all previous activity would be an ancestor of the current exchange. That is, if an incoming message is split into part1 and part2, which are then each processed separately, I don't want to consider the processing of part1 when calculating the history of part2.
A TraceEventHandler has this method:
#Override
public void traceExchange(ProcessorDefinition<?> node, Processor target,
TraceInterceptor traceInterceptor,Exchange exchange) throws Exception {
}
and I expected that there would be an Exchange method like Exchange getPreviousExchange() that I could call inside traceExchange, but I can find no such thing.
Any advice? I'm not married to using a custom TraceEventHandler if there's a better way to do this.
Thanks.
You can find the previous Exchange id by looking up the exchange property with the key "CamelCorrelationId".
If you want to track the post-split processing as separate branches, then you need to consider the Camel property "CamelSplitIndex". This property will indicate which iteration of the split you're processing and when combined with the CamelCorrelationId as William suggested, will provide the full picture.
I have a in/out producer in Camel that only hangs around for a limited time before getting back to the caller. Some times this naturally results in a dead letter item and an exception being caught by the caller when the response is late.
What I would like to do is have the caller receive a timeout message instead of an exception and the item to never end up in the DLQ. Naturally I could put a listener on the DLQ but as the item has a home to go to it shouldn't really ever get to the DLQ.
Does anyone have a pattern for this? How would it be done? There are redundant consumer patterns (see Camel in Action link) but this is kind of a combined producer/consumer problem generated by the in/out pattern.
Sounds like you are using the Dead Letter Channel error handler, try using the noErrorHandler - http://camel.apache.org/error-handler
It might be a silly question, but say I have a hughe message that I want to process with Camel. How will the number of steps in my route affect the memory usage? Does camel deep copy my message payload for every step in the route, even if the DSL-step only reads from the message or does it do something smart here?
Is it better to keep the route down and do things in a "hughe" bean for large messages or not?
This is an example route that does various things, but not changing the payload.
from("foo:bar")
.log(..)
.setProperty(..)
.setHeader(..)
.log(..)
.choice()
.when(simple(... ) )
.log(..)
.to(..)
.when(simple(..))
.log(..)
.to(..)
.end()
from my understanding, for a simple pipelined route like this, an Exchange is created containing the body once and passed along each step in the route. Other EIPs do cause the Exchange to be copied though (like multicast, wiretap, etc)...
as well, if you have steps along the route which interface with external resources which could result in any type of copy/clone/conversion/serialization of the body unnecessarily, then you might use something like the claim check pattern to reduce this.
The camel exchange is the same through the route the message objects are copied or recereated in the steps. The body is just referenced though. So normally you should not have a problem.
This is handled by each camel processor individually though. So some of the processors may copy the body. Typically this is the case when the processor really works on the body. So in this case it can not be avoided.