apache camel - parallel processor then join output - parallel-processing

Question

I hope to do a parallel processing of two processors (fetching different info from different sources) then when both completed, i wanted to have access to both output for further processing (e.g. comparisons).
Something of sort:
from("direct:start)
.processor("process1")
.processor("process2")
.to("direct:compare");
Except I need both output from process1 and process2 to be available in "compare" endpoint.

Answer 1

This is one way to achieve using multicast and aggregation strategy,
public class App {
public static void main(String[] args) throws Exception {
CamelContext context = new DefaultCamelContext();
context.addRoutes(myRoute());
context.startRoute("start");
context.start();
ProducerTemplate producerTemplate = context.createProducerTemplate();
producerTemplate.sendBody("direct:start", null);
Thread.sleep(10_000);
context.stop();
}
private static RouteBuilder myRoute() {
return new RouteBuilder() {
#Override
public void configure() throws Exception {
from("direct:start").routeId("start")
.multicast(new MyAggregationStrategy())
.parallelProcessing()
.to("direct:process1", "direct:process2", "direct:process3")
.end()
.to("direct:endgame");
from("direct:process1")
.process(e -> {
ArrayList<String> body = Lists.newArrayList("a", "b", "c");
e.getIn().setBody(body);
});
from("direct:process2")
.process(e -> {
ArrayList<String> body = Lists.newArrayList("1", "2", "3");
e.getIn().setBody(body);
});
from("direct:process3")
.process(e -> {
ArrayList<String> body = Lists.newArrayList("#", "#", "$");
e.getIn().setBody(body);
});
from("direct:endgame")
.process(e -> {
log.info(" This final result : " + e.getIn().getBody());
});
}
};
}
}
//This is where we can aggregate results of the process which is running in parallel
class MyAggregationStrategy implements AggregationStrategy {
#Override
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
ArrayList<Object> objects = Lists.newArrayList();
if (oldExchange == null) {
return newExchange;
}
Object o = oldExchange.getIn().getBody();
Object n = newExchange.getIn().getBody();
objects.add(o);
objects.add(n);
newExchange.getIn().setBody(objects);
return newExchange;
}
}