Spring Integration and Apache Camel

Solution Using Spring Integration:

The Gateway component is easily configured using the following entry in the Spring Configuration. Internally Spring Integration uses AOP to hook up a component which routes the requests from an internal input channel and waits for the response in the response channel.

<si:gateway default-reply-channel="exit" default-request-channel="enter" id="reportGenerator" service-interface="org.bk.report.ReportGenerator">
</si:gateway>

The component to Split the Input Report Request to Section Request is fairly straightforward:

public class SectionRequestSplitter {    
    public List split(ReportRequest reportRequest){
        return reportRequest.getSectionRequests();
    }

}

and to hook this splitter with Spring Integration:

<bean class="org.bk.report.common.SectionRequestSplitter" id="sectionRequestSplitterBean">

<si:splitter id="sectionRequestSplitter" input-channel="enter" method="split" output-channel="sectionRequestToXMLChannel" ref="sectionRequestSplitterBean">

</si:splitter></bean>

Next, to transform the Section Request to an XML format - The component is the following:

public class SectionRequestToXMLTransformer {
    public String transform(SectionRequest sectionRequest){
 //this needs to be optimized...purely for demonstration of the concept
        String sectionRequestAsString = "<section><meta><entityId>" + sectionRequest.getEntityId()
        + "</entityId><sectionName>" + sectionRequest.getSectionId()
        + "</sectionName></meta></section>";
        
        return sectionRequestAsString;
        
    }
}

and is hooked up in the Spring Integration configuration file in the following way:

<bean id="sectionRequestToXMLBean" class="org.bk.report.common.SectionRequestToXMLTransformer"/>
<si:transformer input-channel="sectionRequestToXMLChannel" ref="sectionRequestToXMLBean" method="transform" output-channel="sectionRequestChannel"/>

To send an XML over http request using the Section Request XML to a section Service:

<http:outbound-gateway id="httpHeaderGateway"
  request-channel="sectionRequestChannel" reply-channel="sectionResponseChannel"
  default-url="${sectionBaseURL}/section" extract-request-payload="true"
  charset="UTF-8" request-timeout="1200" />

To transform the Section Response XML to a Section Object - The component is the following:

public class SectionResponseXMLToSectionTransformer {
 public Section transform(String sectionXML) {
  SAXReader saxReader = new SAXReader();
  Document document;
  String sectionName = "";
  String entityId = "";
  try {
   document = saxReader.read(new StringReader(sectionXML));

   sectionName = document
     .selectSingleNode("/section/meta/sectionName").getText();
   entityId = document.selectSingleNode("/section/meta/entityId")
     .getText();
  } catch (DocumentException e) {
   e.printStackTrace();
  }
  return new Section(entityId, sectionName, sectionXML);
 }
}

and is hooked up in the Spring Integration configuration file in the following way:

<bean id="sectionResponseXMLToSectionBean" class="org.bk.report.common.SectionResponseXMLToSectionTransformer" />
<si:transformer input-channel="sectionXMLResponseChannel"
  ref="sectionResponseXMLToSectionBean" method="transform" output-channel="sectionResponseChannel" />

To aggregate the Sections together into a report, the component is the following::

public class SectionResponseAggregator {

    public Report aggregate(List<Section> sections) {
        return new Report(sections);
    }

}

and is hooked up in the Spring Integration configuration file in the following way:

<bean id="sectionResponseAggregator" class="org.bk.report.common.SectionResponseAggregator"/>
<si:aggregator input-channel="sectionResponseChannel" output-channel="exit" ref="sectionResponseAggregator" method="aggregate"/>

This completes the Spring Integration implementation for this Integration Problem. The following is the complete Spring Integration configuration file:

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context" xmlns:si="http://www.springframework.org/schema/integration"
	xmlns:http="http://www.springframework.org/schema/integration/http"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
	http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration-1.0.xsd	
	http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
	http://www.springframework.org/schema/integration/http http://www.springframework.org/schema/integration/http/spring-integration-http-1.0.xsd
	">

	<context:property-placeholder />
	<si:channel id="enter" />

	<si:channel id="exit" />

	<si:gateway id="reportGenerator" default-request-channel="enter"
		default-reply-channel="exit" service-interface="org.bk.report.ReportGenerator" />

	<si:channel id="sectionRequestToXMLChannel" />
	<si:splitter id="sectionRequestSplitter" input-channel="enter"
		ref="sectionRequestSplitterBean" method="split" output-channel="sectionRequestToXMLChannel" />

	<si:channel id="sectionRequestChannel" />
	<si:transformer input-channel="sectionRequestToXMLChannel"
		ref="sectionRequestToXMLBean" method="transform" output-channel="sectionRequestChannel" />

	<si:channel id="sectionXMLResponseChannel" />
	<http:outbound-gateway id="httpHeaderGateway"
		request-channel="sectionRequestChannel" reply-channel="sectionXMLResponseChannel"
		default-url="${sectionBaseURL}/section" extract-request-payload="true"
		charset="UTF-8" request-timeout="1200" />

	<si:channel id="sectionResponseChannel" />
	<si:transformer input-channel="sectionXMLResponseChannel"
		ref="sectionResponseXMLToSectionBean" method="transform" output-channel="sectionResponseChannel" />

	<si:aggregator input-channel="sectionResponseChannel"
		output-channel="exit" ref="sectionResponseAggregator" method="aggregate" />

	<bean id="sectionRequestSplitterBean" class="org.bk.report.common.SectionRequestSplitter" />
	<bean id="sectionRequestToXMLBean" class="org.bk.report.common.SectionRequestToXMLTransformer" />
	<bean id="sectionResponseXMLToSectionBean" class="org.bk.report.common.SectionResponseXMLToSectionTransformer" />
	<bean id="sectionResponseAggregator" class="org.bk.report.common.SectionResponseAggregator" />
		
</beans>

 

A working sample is provided with the article(Download, extract and run "mvn test")

Legacy

Article Resources: 

reportgenerator-camel.zip

reportgenerator-springintegration.zip