I have a route (A) that do some stuff like calling a REST service.
In this route, before calling the REST service, I need to call another REST service, to valorize some data in my app. That new call is in another route (B).
I'm searching for tips to call that second route (B), but with a new "Exchange" (I want no link between exchange in A and B).
from(ROUTE_A)
.routeId(ROUTE_A)
.process(someProcessA())
//I need to call the route B here, but without giving in the current exchange content
//Route A must wait until before route B execution is complete
.process(someProcessB())
.to(http://blahblah.com/)
.end()
Does anyone know a solution ?
Thanks,
Maybe the content-enricher EIP would help
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.
In this drawing
From http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html; wouldn't it be more correct - in Camel terms - to state "consumer" instead of "producer" at the left?
I am thinking that the out-reply at the end of the route goes back to the from("...") endpoint; i.e. the consumer.
Thanks for reporting. The figure was wrong and I was able to edit and update it
The correct figure is online at
https://cwiki.apache.org/confluence/display/CAMEL/Using+getIn+or+getOut+methods+on+Exchange
It takes a little while for the static html page to be updated.
I have 2 routes. The first route uses poll enrich to check if a file is present. The second route uses a poll enrich on the same uri to read and process the file. The first route invokes the second via a SEDA queue, like so:
public void configure() throws Exception {
String myFile = "file://myDir?fileName=MyFile.zip&delete=false&readLock=none";
from("direct:test")
.pollEnrich(myFile, 10000)
.to("seda:myQueue")
;
from("seda:myQueue")
.pollEnrich(myFile, 10000)
.log("Do something with the body")
;
}
As it stands, if I execute the first route, the poll enrich finds a file, but when the poll enrich in the second route executes, it returns a body of null. If I just execute the second route on its own, it retrieves the file correctly.
Why does the second poll enrich return null, is the file locked? (I was hoping using a combination of noop,readLock, and delete=false would prevent any locking)
Does camel consider the second poll enrich as a duplicate, therefore filtering it out? (I have tried implementing my own IdempotentRepository to return false on contains(), but the second pollEnrich still returns null)
You may wonder why I'm trying to enrich from 2 routes, the first route has to check if a number of files exist, only when all files are present (i.e., pollEnrich doesn't return null) can the second route start processing them.
Is there an alternative to pollEnrich that I can use? I'm thinking that perhaps I'll need to create a bean that retrieves a file by URI and returns it as the body.
I'm using camel 2.11.0
I realize this is now an old topic, but I just had a similar problem.
I suggest you try the options:
noop=true
which you already have, and
idempotent=false
To tell Camel it is OK to process the same file twice.
Update after testing:
I actually tested this with both settings as suggested above, it works some times, but under moderate load, it fails, i.e. returns null body for some exchanges, although not all.
The documentation indicates that setting noop=true automatically sets idempotent=true, so I am not sure the idempotent setting is being honoured in this case.
Is there any specific reason why you are not using just one route?
I don't understand why you are using two routes for this. File component can check if the file is there and if it is, pull it. If you are worried about remembering the files so you don't get duplicates, you can use an idempotent repository. At least, based on your question, I don't think you need to complicate the logic using two routes and the content enricher EIP.
the second route returns NULL because the file was already consumed in the first route...if you are just looking for a signal message when all files are present, then use a file consumer along with an aggregator and possibly a claim check to avoid carrying around large payloads in memory, etc...
As you've probably learned this does not work as one might expect
noop=true&idempotent=false
my guess is that Camel ignores idempotent=false and as documented uses instance of MemoryMessageIdRepository. To work around this, one can configure file endpoint to use custom idempotent repo:
noop=true&idempotentRepository=#myRepo
and register custom repository in the registry or spring context:
#Component("myRepo")
public class MyRepo implements IdempotentRepository {
#Override
public boolean contains(Object o) {
return false;
}
...
}
Try pollEnrich with strategyMethodAllowNull="true". By default , this value is false. When it is false, the aggregation strategy looks for the existing Exchange body, to aggregate the content returned from file.
When we make strategyMethodAllowNull="true", the existing body is considered as null. So every time , the content of the file is set into the current exchange body
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.
What I want to be able to do is following:
from(...)
.replyWith()
.from(...)
.end()
So that the response to my producer is taken from the consumption of another endpoint, an example would be something like a REST endpoint for a queue.
Is there an idiomatic way in Camel to be able to do something like the above without grabbing an Endpoint from a CamelContext instance and manually retrieving the contents and setting them into the Exchange?
Can you explain a bit more?
You dont want to just do
from A
to B
from B
to C
So that a message send to A will be send to B. And B is processed in another route, and the response from this will be send back to the first route, which will be used as reply to any client invoking A in the first place.
Also if you want something with dynamic endpoints, then you can use the Recipient List EIP pattern
http://camel.apache.org/recipient-list.html
from("http://0.0.0.0:9001/getResultsFromQueue")
.pollEnrich("activemq:queue:myQueue")
.to("log:test?level=DEBUG");