Apache camel servlet stream closed after split() - apache-camel

Question

I need to post a JSON Camel Servlet, then duplicate the message and split the list. Process each splitted message and finally aggregate and return the servlet response.
However, as soon as the splitter is introduced in the route, I see the Input Stream is being closed and the Servlet cannot write the response back.
Please note that stream caching is enabled as well.
from("servlet:sample")
.log(LoggingLevel.INFO, "Message Received: JSON RQ")
.to("direct:samplejson");
from("direct:samplejson")
.streamCaching()
.setHeader("sampleId", simple("${id}"))
.log(LoggingLevel.INFO, SampleID in Header: ${header.sampleId}")
.unmarshal().json(JsonLibrary.Jackson, Sample.class)
.log(LoggingLevel.INFO, "Converted to JSON: ${body.toString}")
.process("sampleProcessor")
.split().body().streaming()
.choice()
.when().method("sampleProcessor", "isTypeA")
.marshal().jacksonxml(Sample.class)
.endChoice()
.otherwise()
.marshal().jacksonxml(Sample.class)
.end()
.aggregate(SampleAggregationStrategy).header("sampleId").completionSize(2).completionTimeout(1000L)
.to("direct:samplexml");
from("direct:samplexml").marshal().jacksonxml(List.class).log("FINISHED PROCESSING");
Exception:
2017-06-12 12:22:25,311 [apr-8080-exec-2] INFO route1 - FINISHED PROCESSING
2017-06-12 12:22:25,321 [apr-8080-exec-2] ERROR CamelHttpTransportServlet - Error processing request
java.io.IOException: Stream closed
at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:372) ~[catalina.jar:8.0.30]
at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:156) ~[catalina.jar:8.0.30]
at org.apache.camel.util.IOHelper.copy(IOHelper.java:196) ~[camel-core-2.19.0.jar:2.19.0]
at org.apache.camel.http.common.DefaultHttpBinding.copyStream(DefaultHttpBinding.java:432) ~[camel-http-common-2.19.0.jar:2.19.0]
at org.apache.camel.http.common.DefaultHttpBinding.doWriteDirectResponse(DefaultHttpBinding.java:496) ~[camel-http-common-2.19.0.jar:2.19.0]
at org.apache.camel.http.common.DefaultHttpBinding.doWriteResponse(DefaultHttpBinding.java:395) ~[camel-http-common-2.19.0.jar:2.19.0]
at org.apache.camel.http.common.DefaultHttpBinding.writeResponse(DefaultHttpBinding.java:322) ~[camel-http-common-2.19.0.jar:2.19.0]
at org.apache.camel.http.common.CamelServlet.doService(CamelServlet.java:210) [camel-http-common-2.19.0.jar:2.19.0]
at org.apache.camel.http.common.CamelServlet.service(CamelServlet.java:74) [camel-http-common-2.19.0.jar:2.19.0]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) [servlet-api.jar:?]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) [catalina.jar:8.0.30]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.30]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-websocket.jar:8.0.30]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.30]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.30]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) [catalina.jar:8.0.30]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [catalina.jar:8.0.30]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [catalina.jar:8.0.30]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) [catalina.jar:8.0.30]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [catalina.jar:8.0.30]
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) [catalina.jar:8.0.30]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [catalina.jar:8.0.30]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521) [catalina.jar:8.0.30]
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096) [tomcat-coyote.jar:8.0.30]
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674) [tomcat-coyote.jar:8.0.30]
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2500) [tomcat-coyote.jar:8.0.30]
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2489) [tomcat-coyote.jar:8.0.30]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_74]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_74]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.0.30]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_74]
If I remove the splitter and aggregator, I see the Servlet response coming back.
Many Thanks in advance for all the help provided!.

Answer 1

See the Composted Message Processor EIP pattern (http://camel.apache.org/composed-message-processor.html) and the example that uses splitter only which allows you to do a fork/join in the same unit of work, and be able to return a response in the servlet. The splitter only supports an AggregationStrategy you can configure where you aggregate the response. In other words do not use both splitter and aggregator, but only splitter.