LoadRunner GWT to XML Conversion - gwt

Question

We have an application which uses GWT for the communication. I have enabled DFE (In Loadrunner - Vugen) and selected GWT as the option and provided application .WAR file as the input to extract All Application related .jar files.
Recorded the scenario flow, and i see all the requests are converted from GWT to XML format. But then when i reply the test script i am having errors as DFE is not able to convert the HTTP response from GWT fromat to XML format.
What are the other options that we can try to resolve this error and convert to XML format? And is there a way that we can supress the Loadrunner error message, so that it will proceed with the next steps instead of failure?
Do we need any additional .jars for converting HTTP responses?
HTTP Response (In GWT Format): //OK[[],0,5]
Error Message:
Action.c(93): Error -27040: Data Format Extension: Extension: GWT - ERROR
[GWT_DFE] - Failed to parse response:
java.lang.ArrayIndexOutOfBoundsException: -1
java.lang.ArrayIndexOutOfBoundsException: -1
at java.util.ArrayList.elementData(ArrayList.java:403) ~[?:1.8.0-internal]
at java.util.ArrayList.get(ArrayList.java:416) ~[?:1.8.0-internal]
atcom.gdevelop.gwt.syncrpc.SyncClientSerializationStreamReader.readInt(SyncClientSerializationStreamReader.java:450) ~[SyncProxy.jar:?]
at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamReader.readObject(AbstractSerializationStreamReader.java:46) ~[gwt-servlet-2.0.4.jar:?]
at com.hp.dfe.GWT_DFE.deserializeResponseToXML(GWT_DFE.java:462) [classes/:?]
at com.hp.dfe.GWT_DFE.decode(GWT_DFE.java:704) [classes/:?]
at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source) ~[?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0-internal]
at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0-internal]
at com.hp.dfe.GWT_DFE_DYNAMICALLY_REFLECTED.doOperation(GWT_DFE_DYNAMICALLY_REFLECTED.java:70) [classes/:?]
at com.hp.dfe.GWT_DFE_DYNAMICALLY_REFLECTED.decode(GWT_DFE_DYNAMICALLY_REFLECTED.java:60) [classes/:?]
at com.hp.dfe.GWT_DFE_LAUNCHER.decode(GWT_DFE_LAUNCHER.java:456) [classes/:?]
[MsgId: MERR-27040]
Action.c(93): Error -27040: Data Format Extension: Extension: GWT - ERROR [GWT_DFE] - failed to read as a response
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[MsgId: MERR-27040]
Thanks.

Answer 1

That looks like an empty (void return type) response for an old version of gwt - the status was success (//OK), there are no flags set (0), the version is pretty old (5), and the array of strings is empty, since there is no other data to send back. Sounds instead to me like your GWT_DFE class is expecting that all responses always have a value, or that something else is very wrong in how they are handling the response (perhaps they can't handle the old version well? I'd be just blindly guessing at this point, that code isn't publicly available).
If you have a RemoteService method like void sendMessage(SomeObject object), there may be no need for any return type other than the onSuccess response itself. The matching async interface would then have AsyncCallback<Void>, and would not get a return value.