I am migration to Camel 3.20.1 from 2.20.1 and am facing some difficulties with my current workflow.
I have three RouteBuilders with routes which are called in hierarchical order like this.
RouteBuilderA
#Override
public void configure() throws Exception {
errorHandler(deadLetterChannel("direct:dead")
.maximumRedeliveries(2)
.redeliveryDelay(1000));
from("direct:A")
.to("direct:B");
}
RouteBuilderB
#Override
public void configure() throws Exception {
from("direct:B")
.to("direct:C");
}
RouteBuilderC
#Override
public void configure() throws Exception {
errorHandler(noErrorHandler())
from("direct:C")
.throwException(new RuntimeException("Something went wrong"))
.to("direct:end");
}
Current flow:
As you can see in the code, route in RouteBuilder3 will trigger exception which will be passed to RouteBuilder2. From there it will not be handled, as no error handler is defined for that route, and it will fail with stacktrace...
Desired flow:
What I need is to pass that exception to RouteBuilder1 and handle it there where (my global deadLetterChannel) error handler is defined.
One could say, just add errorHandler(noErrorHandler()) into RouteBuilderB, right. That is clear and it works, BUT I don't want that because...
Because, in that case redelivery will kick in and route message through routes in RouteBuilderB and RouteBuilderC. But, as I got exception in RouteBuilderC, I only want to route message through route where it failed, that is RouteBuilderC.
Background:
In old Camel version I somehow managed to make it work by using includeRoutes(injectedRouteBuilder), which is not available anymore. RouteBuilderC bean is injected into RouteBuilderB, which is injected in RouteBuilderA.
Question:
Does anybody knows how to solve that? I cannot find a way to make this work. I tried a lot of things, including getCamelContext().addRoutes(injectedRouteBuilder);.
*p.s. I am aware of recommendation to use inheritance for RouteBuilders, but in my case this is not an option. I need to pass it to RouteBuilder1 as only that one knows to which error queue, message needs to be send. *
Requisite disclaimer about being new to Camel--and, frankly, new to developing generally. I'd like to have a string generated as the output of some function be the source of my camel route which then gets written to some file. It's the first part that seems challenging: I have a string, how do I turn it into a message? I can't write it into a file nor can I use JMS. I feel like it should be easy and obvious, but I'm having a hard time finding a simple guide to help.
Some pseudo-code using the Java DSL:
def DesiredString() {return "MyString";}
// A camel route to be implemented elsewhere; I want something like:
class MyRoute() extends RouteBuilder {
source(DesiredString())
.to("file://C:/out/?fileName=MyFileFromString.txt");
}
I vaguely understand using the bean component, but I'm not sure that solves the problem: I can execute my method that generates the string, but how do I turn that into a message? The "vague" is doing a lot of work there: I could be missing something there.
Thanks!
Not sure if I understand your problem. There is a bit of confusion about what the String should be become: the route source or the message body.
However, I guess that you want to write the String returned by your method into a File through a Camel route.
If this is correct, I have to clarify first the route source. A Camel Route normally starts with
from(component:address)
So if you want to receive requests from remote via HTTP it could be
from("http4:localhost:8080")
This creates an HTTP server that listens on port 8080 for messages.
In your case I don't know if the method that returns the String is in the same application as the Camel route. If it is, you can use the Direct component for "method-like" calls in the same process.
from(direct:input)
.to("file:...");
input is a name you can freely choose. You can then route messages to this route from another Camel route or with a ProducerTemplate
ProducerTemplate template = camelContext.createProducerTemplate();
template.sendBody("direct:input", "This is my string");
The sendBody method takes the endpoint where to send the message and the message body. But there are much more variants of sendBody with different signatures depending on what you want to send it (headers etc).
If you want to dive into Camel get a copy of Camel in Action 2nd edition. It contains everything you need to know about Camel.
Example:Sending String(as a body content)to store in file using camel Java DSL:
CamelContext context = new DefaultCamelContext();
context.addRoutes(new RouteBuilder() {
public void configure() {
from("timer:StringSentToFile?period=2000")
.setBody(simple(DesiredString()))
.to("file:file://C:/out/?fileName=MyFileFromString.txt&noop=true")
.log("completed route");
}
});
ProducerTemplate template = context.createProducerTemplate();
context.start();
In my camel route I want to send part of the output (json path is $._attachments) to another endpoint. This works. However, in a few corner cases it appears some of the json objects do not have this element. I guessed this would result in a CamelSplitSize being 0, and tried to test on that; however, the DefaultErrorHandler seems to kick in, rather than completing the route. What am I doing wrong here?
public class DiscoverAttachmentsFromCouchResponseRoute extends RouteBuilder {
#Override
public void configure() throws Exception
{
JsonPathExpression jsonPathExpression = new JsonPathExpression("$._attachments");
Predicate no_attachments = header("CamelSplitSize").isEqualTo("0");
errorHandler(
deadLetterChannel("broker1:queue:dlq.jsonobject.queue")
.maximumRedeliveries(3)
);
from("broker1:queue:input.jsonobject.queue")
.routeId("DiscoverAttachmentsFromCouchResponseRoute")
.threads(2)
.split(jsonPathExpression)
.marshal().json(JsonLibrary.Jackson,true)
.to("broker1:queue:with.attachments.queue")
.choice()
.when(no_attachments)
.log("No attachments found.")
.to("broker1:queue:no.attachments.queue")
.otherwise()
.log("A grand total of '${header.CamelSplitSize}' attachments were found.")
.endChoice();
}
}
Edit somethimes the answer is too obvious... I was looking at the wrong place. Why do I always seem to find an answer a few minutes after I asked it? Am direly in need of a rubber duck.
I changed the route a bit; Rather than handling the issue after the split, I should do it prior to the split:
.choice()
.when().jsonpath("$._attachments", true)
.to("vm://withattach")
.otherwise()
.to("vm://withoutattach")
.endChoice();
Then I only needed two new consumers from the vm://* and do the logic there. This seems to work. In jsonpath I can skip the exception which I cannot do in the JsonPathExpression nor in the split();
I'm using Camel Rest (with restlet component) and I have the following APIs:
rest("/order")
.get("/{orderId}").produces("application/json")
.param().dataType("int").type(RestParamType.path).name("orderId").endParam()
.route()
.bean(OrderService.class, "findOrderById")
.endRest()
.get("/customer").produces("application/json").route()
.bean(OrderService.class, "findOrderByCustomerId")
.endRest()
The problem is that the /order/customer doesn't works (see Exception below). The parameters for /customer comes from JWT...
java.lang.String to the required type: java.lang.Long with value
customer due Illegal characters: customer
I think that camel is confusing the ../{orderId} parameter with .../customer.
If I change the /customer for /customer/orders it's works.
The same idea in Spring Boot could have done with:
#RequestMapping("/order/{orderId}")
public Order getOrder(#PathVariable Long orderId) {
return orderRepo.findOne(orderId);
}
#RequestMapping("/order/customer")
public List<Order> getOrder() {
return orderRepo.listOrderByCustomer(1l);
}
Any idea about what's happening?
Try changing the order of your GET operations in the Camel Rest DSL. The restlet component has some issues in matching the best possible methods.
There is a couple of JIRA tickets related to this:
https://issues.apache.org/jira/browse/CAMEL-12320
https://issues.apache.org/jira/browse/CAMEL-7906
I would like to process both request and response messages at the end of my route. However, I do not see a way how to access the original request message.
I have the terrible feeling I am struggling with some basic concept.
Here is a simple example route in DSL to outline my problem (streamCaching is enabled for the whole context):
from("activemq:queue:myQueue")
.to("log:" + getClass().getName() + "?showOut=true")
.to("http://localhost:8080/someBackend")
.log("Now in.Body returns this: ${in.body} and out.Body this: ${out.body}")
.to("log:" + getClass().getName() + "?showOut=true");
Here is an according excerpt from my logs (line-breaks edited for better reading). As one can see, the original SOAP message is lost once the http server replied, and the SOAP response object is stored in the inBody of the message.
2012-09-25 17:28:08,312 local.bar.foo.MyRouteBuilder INFO -
Exchange[ExchangePattern:InOut, BodyType:byte[],
Body:<?xml version="1.0" encoding="UTF-8"?><env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"><env:Header /><env:Body><urn:someRequest xmlns:urn="http://foo.bar.local/ns"></urn:someRequest></env:Body></env:Envelope>,
Out: null]
2012-09-25 17:28:08,398 org.apache.camel.component.http.HttpProducer DEBUG -
Executing http POST method: http://localhost:8080/someBackend
2012-09-25 17:28:09,389 org.apache.camel.component.http.HttpProducer DEBUG -
Http responseCode: 200
2012-09-25 17:28:09,392 route2 INFO -
Now in.Body returns this: <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><ns2:someResponse xmlns:ns2="http://foo.bar.local/ns"</ns2:someResponse></soap:Body></soap:Envelope>
and out.Body this:
2012-09-25 17:28:09,392 local.bar.foo.MyRouteBuilder INFO -
Exchange[ExchangePattern:InOut,
BodyType:org.apache.camel.converter.stream.InputStreamCache,
Body:[Body is instance of org.apache.camel.StreamCache],
Out: null]
I would have expected to have in.body and out.body be preserved across the whole route?
Alternative solutions I am considering:
Make use of the Correlation Identifier pattern to correlate both request and reply. But would this preserve the message bodies as well? Also, my request/reply messages do not have unique identifiers for correlation.
Write a custom bean, which performs the call to the http backend, processing both request and reply objects (but this is basically a no-Camel solution, reinventing the wheel and hence not preferred)
Already failed approaches:
I tried to access the original request message using a Processor like this at the end of my route, with no success:
process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
Message originalInMessage = exchange.getUnitOfWork().getOriginalInMessage();
logger.debug(originalInMessage.getBody(String.class));
logger.debug(exchange.getIn().getBody(String.class));
}
});
Thanks for any help
Simply store the original body of the in message in a header or a property and retrieve it at the end:
from("activemq:queue:myQueue")
.setProperty("origInBody", body())
.to("http://localhost:8080/someBackend")
After the http call you can then access the property origInBody.
First, this article shows very well how in and out works in camel: http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html
Typically, the out message is not always used, but rather copied from the in-message in each step.
In your case, where you want the original message to stay around til the end of the route, you could go ahead with the Enrichment EIP. http://camel.apache.org/content-enricher.html
Your route would be something like this:
public class MyAggregationStrategy implements AggregationStrategy {
public Exchange aggregate(Exchange orig, Exchange httpExchange){
// if you want to check something with the Http request, you better do that here
if( httpExchange is not correct in some way )
throw new RuntimeException("Something went wrong");
return orig;
}
}
AggregationStrategy aggStrategy = new MyAggregationStrategy();
from("activemq:queue:myQueue")
.enrich("http://localhost:8080/someBackend",aggStrategy)
.//keep processing the original request here if you like, in the "in" message
One of the biggest problem of camel, is the ease to misuse it. The best way to use it correctly is to think in terms of EIP : one of the main goals of camel, is to implement EIP in its DSL.
Here is a list of EIP
Now think about it. You want the request and the response at the end, for what use ? Logging, Aggregation, ... ? For logging, a correlationId should suffice, so I presume you need it to create a response, based on both request and the proxied-response. If that's what you want, you could do something like
from("direct:receiveRequest")
.enrich("direct:proxyResponse", new RequestAndResponseAggregationStrategy())
You will have the opportunity to merge your Request (in oldExchange) and your Response (in newExchange).
With all the due respect I have for Christian Schneider, I do think the idea of putting the request in a property that could be reused later is a bad design. By doing it, you create side-effect between your routes. If your route is a subroute for another, you'll maybe erase their property. If you store it to put it back later, maybe you should do something like
from("direct:receiveRequest")
.enrich("direct:subRouteToIgnoreResponse", AggregationStrategies.useOriginal())
A really really bad design that I have done too many time myself is to do :
from("direct:receiveRequest")
.to("direct:subroute")
from("direct:subroute")
.setProperty("originalBody", body())
.to("direct:handling")
.transform(property("originalBody")
This will lead to "properties/headers hell", and to routes that are just a successive call of processors.
And if you can't think of a solution of your problem with EIP, you should maybe use camel only to access their components. For example, something like :
from("http://api.com/services")
.to(new SomeNotTranslatableToEIPProcessor())
.to("ftp://destination")
But don't forget that those components has their own goals : creating a common abstraction between similar behaviour (e.g, time based polling consumer). If you have a very specific need, trying to bend a camel component to this specific need can lead to huge chunk of code not easily maintainable.
Don't let Camel become your Golden Hammer anti-pattern
I often use an aggregation strategy, which preserves the old exchange and puts the result of the enrich into a header:
import org.apache.camel.Exchange;
import org.apache.camel.processor.aggregate.AggregationStrategy;
public class SetBodyToHeaderAggregationStrategy implements AggregationStrategy {
private String headerName = "newBody";
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
oldExchange.getIn().setHeader(headerName, newExchange.getIn().getBody());
return oldExchange;
}
#SuppressWarnings("unused")
public void setHeaderName(String headerName) {
this.headerName = headerName;
}
}
Now you can use it like this:
<enrich strategyRef="setBodyToHeaderAggregationStrategy">
<constant>dosomething</constant>
</enrich>
<log loggingLevel="INFO" message="Result body from enrich: ${header.newBody}. Original body: ${body}" loggerRef="log"/>