Mule Esb 3.2.1: gathering the results of a splitter and outputting results as XML - esb

Question

I've been struggling through SO and the Mule forums but can't find a solution that works. The esb takes in a single request containing an id, which creates an XML payload that is composed a list of related ids. This XML payload is then split and sent to a transformer that takes each related id to get some meta data. The results are then supposed to be combined together to make an XML response. The problem I am having is that no matter how I transform the final result set, I always get back the document with an encapsulating string "??sr)java.util.concurrent.CopyOnWriteArrayListx]....""x
Any ideas/comments would be greatly appreciated.
Here is the mule-config I am using:
<http:connector name="HttpConnector" doc:name="HTTP\HTTPS"/>
<expression-transformer name="ExtractId" doc:name="Expression">
<return-argument evaluator="xpath" expression="//string[1]"/>
</expression-transformer>
<flow name="myFlow1" doc:name="myFlow1">
<http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081" path="incoming/path/" connector-ref="HttpConnector" doc:name="HTTP"/>
<custom-transformer encoding="UTF-8" class="mycomponents.transformers.SubscriberRequestTransformer" doc:name="Create Hub Id Requests"/>
<mulexml:object-to-xml-transformer doc:name="Object to XML"/>
<splitter evaluator="xpath" expression="//entry/list/string" enableCorrelation="ALWAYS" doc:name="Splitter"/>
<transformer ref="ExtractId" doc:name="Transformer Reference"/>
<logger message="#[payload:]" level="INFO" doc:name="Logger"/>
<custom-transformer encoding="UTF-8" class="mycomponents.transformers.HubQueryProcessor" doc:name="Create Hub Id Requests"/>
<collection-aggregator />
<component class="mycomponents.TopicResponseAggregatorComponent" doc:name="Collect requests" />
<logger message="Aggregated Content (#[groovy:payload.size()] elements): \n#[payload:]" level="INFO" doc:name="Logger"/>
<logger message="#[payload:]" level="INFO" doc:name="Logger"/>
</flow>
I've resolved the issue. Although I don't quite understand why it's different but I'm assuming it has to do with some of the mule "magic". I split up the flow into multiple flows which is what I was eventually going to do anyways. However, by doing this the problem went away.
FYI: here's the updated flow:
<flow name="myFlow1" doc:name="myFlow1">
<http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081" path="url/for/service/" connector-ref="HttpConnector" doc:name="HTTP"/>
<flow-ref name="createHubIdRequestsFlow" doc:name="Map To Hub Ids" doc:description="Takes in the situation id passed in by the client. Does the query lookup versus the content mapping tables. creates the correspondng requests for meta data information to the provider(s)"/>
<flow-ref name="getTopicRequests" doc:name="Process Provider Reponses" doc:description="For each JSON response returned from the provider, transform it into an XML representation of that data"/>
<flow-ref name="buildResponseFlow" doc:name="Build final response" doc:description="piece all the messages together into a single object as a string"/>
<response>
<message-properties-transformer>
<add-message-property value="text/xml" key="Content-Type" />
</message-properties-transformer>
</response>
</flow>

Answer 1

By default, the message properties transformer stores new properties in the "invocation" scope. You need to set the content-type on the "outbound" scope so it is used by the inbound HTTP endpoint in its response phase.
Try this:
<response>
<message-properties-transformer scope="outbound">
<add-message-property value="text/xml" key="Content-Type" />
</message-properties-transformer>
</response>