tRESTResponse: Exception Rest response already sent.

[Anonymous]

So I am working on reconciliation service for OpenRefine. OpenRefine send query with the following payload as Form.
Below an example of query sent by OpenRefine

queries={"q0":{"query":"Joe","limit":3},"q1":{"query":"John","limit":3},"q2":{"query":"Henry","limit":3},"q3":{"query":"Willliam","limit":3}}

My Talend job:
1. parse the payload into different record for q0, q1 ....
2. do some computing for each record and build individual JSON answer using a tMap (screenshot 02)
3. wrap all results in a single payload and pass it to tRESTResponse (screenshot 03)

As the first query got parsed the job failed with the following Exception:

Exception in component tRESTResponse_2
java.lang.RuntimeException: Rest response already sent.
	at openrefinereconciliation.restservice2_0_1.RESTService2.tRESTRequest_1_LoopProcess(RESTService2.java:8091)
	at openrefinereconciliation.restservice2_0_1.RESTService2$RestServiceProviderImpl4TalendJob.processRequest(RESTService2.java:598)
	at openrefinereconciliation.restservice2_0_1.RESTService2$RestServiceProviderImpl4TalendJob.queries(RESTService2.java:700)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.apache.cxf.service.invoker.AbstractInvoker.performInvocation(AbstractInvoker.java:180)
	at org.apache.cxf.service.invoker.AbstractInvoker.invoke(AbstractInvoker.java:96)
	at org.apache.cxf.jaxrs.JAXRSInvoker.invoke(JAXRSInvoker.java:192)
	at org.apache.cxf.jaxrs.JAXRSInvoker.invoke(JAXRSInvoker.java:100)
	at org.apache.cxf.interceptor.ServiceInvokerInterceptor$1.run(ServiceInvokerInterceptor.java:57)
	at org.apache.cxf.interceptor.ServiceInvokerInterceptor.handleMessage(ServiceInvokerInterceptor.java:93)
	at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:272)
	at org.apache.cxf.transport.ChainInitiationObserver.onMessage(ChainInitiationObserver.java:121)
	at org.apache.cxf.transport.http_jetty.JettyHTTPDestination.serviceRequest(JettyHTTPDestination.java:355)
	at org.apache.cxf.transport.http_jetty.JettyHTTPDestination.doService(JettyHTTPDestination.java:319)
	at org.apache.cxf.transport.http_jetty.JettyHTTPHandler.handle(JettyHTTPHandler.java:72)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1088)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1024)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:255)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
	at org.eclipse.jetty.server.Server.handle(Server.java:370)
	at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:489)
	at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:960)
	at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1021)
	at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:865)
	at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240)
	at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
	at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:668)
	at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
	at java.lang.Thread.run(Thread.java:722)

and I am clueless on what I am doing wrong? Is my document not formed properly at the tXMLMap level? Did I missed some configuration in the tRESTResponse (ie should I configure specific response header?)
Thanks in advance for your help.

[Anonymous]

Hi
The error message suggests that an attempt is made to repeatedly write a response into the back channel representing a current client request.
Unfortunately it is not possible to do it at the Studio level, there's an enhancement request to support streaming of the response data into a single tRESTRequest response, but it is not supported yet.
Can you open an enhancement request on your own and I will link to it from the internal JIRA issue ?

Cheers, Sergey

[Anonymous]

Thanks Sergey,
I've created the following issue: https://jira.talendforge.org/browse/TESB-13475
I was not able to track back the issue to request to support streaming of the response data into a single tRESTRequest response. May you provide a link to it?
thanks

[Anonymous]

Thanks, I've linked to it from TESB-12039
Cheers, Sergey

[Anonymous]

Hi,
this may be helpful: setting the XMLMap's output option "All in one" to "true" shovels all rows to one document before passing the row out... this helped me in a similar problem
regards,
Patrick