Hello community
I use camel version 3.7.0 in my project.
I just noticed something very interesting while playing around with
Multicast (with an aggregation strategy to merge back)
CASE 1: When a path which encountered an exception merges *FIRST*
JAVA - DSL:
import org.apache.camel.builder.RouteBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class MulticastTestRoute extends RouteBuilder {
@Autowired
SimpleFlowMergeAggregator simpleFlowMergeAggregator;
@Override
public void configure() throws Exception {
onException(Exception.class)
.useOriginalMessage()
.handled(true)
.log("Exception handler invoked")
.transform().constant("{\"data\" : \"err\"}")
.end();
from("jetty:http://localhost:8081/mysql?httpMethodRestrict=GET";)
.log("received request")
.multicast(simpleFlowMergeAggregator)
.parallelProcessing().to("direct:A", "direct:B")
.end()
.log("Aggregated results ${body}")
.log("Another log")
.end();
from("direct:A")
.log("Executing PATH_1 - exception path")
.transform(constant("DATA_FROM_PATH_1"))
.throwException(new Exception("USER INITIATED EXCEPTION")) //
simulating exception scenario here
.log("PATH_1")
//.delayer(100)
.end();
from("direct:B")
.log("Executing PATH_2 - success path")
.delayer(100)
.transform(constant("DATA_FROM_PATH_2"))
.log("PATH_2")
.end();
}
}
LOG:
18:04:20.596 [qtp1886136102-138] INFO route3 - receivedrequest
18:04:20.604 [Camel (camel-1) thread #7 - Multicast] INFOroute4 - Executing
PATH_1 - exception path
18:04:20.609 [Camel(camel-1) thread #7 - Multicast] INFO route4 -
Exception handler invoked
18:04:20.610 [Camel (camel-1) thread #7 - Multicast] INFO
com.huawei.camel.core.route.SimpleFlowMergeAggregator - Inside aggregator
{"data" : "err"}
18:04:20.704 [Camel (camel-1) thread #6 -Multicast] INFO route5 -
Executing PATH_2 - success path
18:04:20.905 [Camel (camel-1) thread #6 - Multicast] INFO route5 - PATH_2
18:04:20.905 [Camel (camel-1) thread #6 - Multicast] INFO
com.huawei.camel.core.route.SimpleFlowMergeAggregator - Inside aggregator
DATA_FROM_PATH_2
CASE 2: When a path which encountered an exception merges *LATER*
JAVA-DSL:
@Component
public class MulticastTestRoute extends RouteBuilder {
@Autowired
SimpleFlowMergeAggregator simpleFlowMergeAggregator;
@Override
public void configure() throws Exception {
onException(Exception.class)
.useOriginalMessage()
.handled(true)
.log("Exception handler invoked")
.transform().constant("{\"data\" : \"err\"}")
.end();
from("jetty:http://localhost:8081/mysql?httpMethodRestrict=GET";)
.log("received request")
.multicast(simpleFlowMergeAggregator)
.parallelProcessing().to("direct:A", "direct:B")
.end()
.log("Aggregated results ${body}")
.log("Another log")
.end();
from("direct:A")
.log("Executing PATH_1 - exception path")
.transform(constant("DATA_FROM_PATH_1"))
.throwException(new Exception("USER INITIATED EXCEPTION")) //
simulating exception scenario here
.log("PATH_1")
delayer(100)
.end();
from("direct:B")
.log("Executing PATH_2 - success path")
//.delayer(100)
.transform(constant("DATA_FROM_PATH_2"))
.log("PATH_2")
.end();
}
}
LOG:
18:08:14.136 [qtp2070645994-143] INFO route3 - received request
18:08:14.146 [Camel (camel-1) thread #6 - Multicast] INFO route5 -
Executing PATH_2 - success path
18:08:14.147 [Camel (camel-1) thread #6 - Multicast] INFO route5 - PATH_2
18:08:14.147 [Camel (camel-1) thread #6 - Multicast] INFO
com.huawei.camel.core.route.SimpleFlowMergeAggregator - Inside aggregator
DATA_FROM_PATH_2
18:08:14.246 [Camel (camel-1) thread #7 -Multicast] INFO route4 -
Executing PATH_1 - exception path
18:08:14.551 [Camel (camel-1) thread #7 - Multicast] INFO route4 -
Exception handler invoked
18:08:14.652 [Camel (camel-1) thread #7 - Multicast] INFO
com.huawei.camel.core.route.SimpleFlowMergeAggregator - Inside aggregator
{"data" : "err"}
18:08:14.653 [Camel (camel-1) thread #7 - Multicast] INFO route3 -
Aggregated results DATA_FROM_PATH_2,{"data" : "err"}
18:08:14.653 [Camel (camel-1) thread #7 - Multicast] INFO route3 - Another
log
My Observations : When the path which encountered an exception merges
first in the aggregator, for some reason the remaining part of the
flow doesn't get executed. On the other hand, if a path which
encountered an exception comes later, it still continues to route the
remaining part of the flow. You can see I simulate both scenarios
using a delayer eip.
When i say "remaining part of the flow", I refer to the remaining
loggers => *.log("Aggregated results ${body}").log("Another log")*
Is this some sort of BUG in the framework or is it there for a reason?
Cheers
Reji Mathews
