Aggregator is failing after upgrading to Spring-Integration 4 - spring-integration

Question

We are using Spring-Integration in our project. We are trying to migrate from spring-integration-core:jar:3.0.1.RELEASE to spring-integration-core:jar:4.3.2.RELEASE, java 8, spring 4. We are running into issues with aggregator. Weirdly, the aggregator's method is not called during the execution. The configuration is shown below:
<!-- Store the original payload in header for future purpose -->
<int:header-enricher default-overwrite="true" should-skip-nulls="true" >
<int:header name="${headerNames.originalPayload}" expression="payload" />
</int:header-enricher>
<!-- split the issues-->
<int-xml:xpath-splitter >
<int-xml:xpath-expression expression="//transaction"/>
</int-xml:xpath-splitter>
<int:service-activator ref="httpOutboundGatewayHandler" method="buildHttpOutboundGatewayRequest" />
<int:header-filter header-names="accept-encoding"/>
<int-http:outbound-gateway url-expression="headers.restResourceUrl"
http-method-expression="headers.httpMethod"
extract-request-payload="true"
expected-response-type="java.lang.String">
</int-http:outbound-gateway>
<int:service-activator ref="msgHandler" method="buildMessageFromExtSysResponse" />
<int-xml:xslt-transformer xsl-resource="${stylesheet.PQGetWorklist-Response-MoveSources}" />
</int:chain>
<int:aggregator input-channel="PQGetWorklist-Aggregate-sources" output-channel="PQGetWorklist-MoveSourcesUnderIssues"
ref="xmlAggregator" method="aggregateSources">
</int:aggregator>
In the above code, <int-http:outbound-gateway is getting executed, but the XmlAggregator.aggregateSources is not called for unknown reasons. I could see that the message is sent to on the channel PQGetWorklist-Aggregate-sources. But from there the aggregator's method aggregateSources is not called. As a result, we are getting No reply received within timeout. Remember the same configuration is working fine with spring-integration-core:jar:3.0.1.RELEASE. The problem is seen only when we upgrade it to spring-integration-core:jar:4.3.2.RELEASE .
Here is my XmlAggregator.java
public class XmlAggregator {
private static final Logger logger = Logger.getLogger(XmlAggregator.class);
public Message aggregateSources(List < Message > messages) throws DocumentException {
Document mainDom = XmlParserUtil.convertString2Document("<Results> </Results>");
Document splitMessageDom = XmlParserUtil.convertString2Document(messages.get(0).getPayload().toString());
Document IssuesDom = XmlParserUtil.convertString2Document("<Issues> </Issues>");
Document sourcesDom = XmlParserUtil.convertString2Document("<RetrievedSources> </RetrievedSources>");
if(messages.get(0).getHeaders().get("jobDesignerJobName").equals("PQIssueInquiry")){
//extract callerType node
Element callerType = XmlParserUtil.getXmlElements(XmlParserUtil.convertString2Document(messages.get(0).getPayload().toString()), "//callerType").get(0);
//add callerType to root node
mainDom.getRootElement().content().add(callerType);
}
//extract sort node
Element sort = XmlParserUtil.getXmlElements(XmlParserUtil.convertString2Document(messages.get(0).getPayload().toString()), "//sort").get(0);
//add sort to root node
mainDom.getRootElement().content().add(sort);
//get all the issues
List < Element > transactionElements = XmlParserUtil.getXmlElements(splitMessageDom, "//transaction");
for (Element issue: transactionElements) {
// add all the issues to the IssuesDom
IssuesDom.getRootElement().content().add(issue);
}
//add all the issues to the root node
XmlParserUtil.appendChild(mainDom, IssuesDom, null);
for (Message source: messages) {
Document sourcesTempDom = XmlParserUtil.convertString2Document(source.getPayload().toString());
Reader xml = new StringReader((String) source.getPayload());
SAXReader reader = new SAXReader();
Document document = reader.read(xml);
//get all the sources
List < Element > sourceElements = XmlParserUtil.getXmlElements(sourcesTempDom, "//sources");
for (Element sources: sourceElements) {
//add all the sources to sourcesDom
sourcesDom.getRootElement().content().add(sources);
}
}
// add all the sources to the root node
XmlParserUtil.appendChild(mainDom, sourcesDom, null);
MessageBuilder < ? > msgBuilder = MessageBuilder.withPayload(mainDom.asXML());
Message message = msgBuilder.build();
logger.debug("aggregateSources Results after aggregation " + mainDom.asXML());
return message;
}
}
Any thoughts?

Answer 1

Starting with version 4.2 the XPathMessageSplitter is based on the iterator functionality by default:
<xsd:attribute name="iterator" default="true">
<xsd:annotation>
<xsd:documentation>
The iterator mode: 'true' (default) to return an 'java.util.Iterator'
for splitting 'payload', 'false to return a 'java.util.List'.
Note: the 'list' contains transformed nodes whereas with the
'iterator' each node is transformed while iterating.
</xsd:documentation>
</xsd:annotation>
<xsd:simpleType>
<xsd:union memberTypes="xsd:boolean xsd:string" />
</xsd:simpleType>
</xsd:attribute>
Do not overhead the memory with the size interest and pull the data from the target source on demand.
The functionality can be turned off via iterator="false" option.