26.3 Namespace support for xml transformers

Namespace support for all xml transformers is provided in the Spring Integration xml namespace, a template for which can be seen below. The namespace support for transformers creates an instance of either EventDrivenConsumer or PollingConsumer according to the type of the provided input channel. The namespace support is designed to reduce the amount of xml configuration by allowing the creation of an endpoint and transformer using one element.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:integration="http://www.springframework.org/schema/integration"
       xmlns:si-xml="http://www.springframework.org/schema/integration/xml"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/integration
           http://www.springframework.org/schema/integration/spring-integration-1.0.xsd
           http://www.springframework.org/schema/integration/xml
           http://www.springframework.org/schema/integration/xml/spring-integration-xml-1.0.xsd">
</beans>

The namespace support for XmlPayloadUnmarshallingTransformer is shown below. Since the namespace is now creating an instance of MessageEndpoint rather than a transformer a poller can also be nested within the element to control the polling of the input channel.

<si-xml:unmarshalling-transformer id="defaultUnmarshaller"
    input-channel="input"
    output-channel="output"
    unmarshaller="unmarshaller"/>

<si-xml:unmarshalling-transformer id="unmarshallerWithPoller"
    input-channel="input"
    output-channel="output"
    unmarshaller="unmarshaller">
    <si:poller>
        <si:interval-trigger interval="2000"/>
    </si:poller>
<si-xml:unmarshalling-transformer/>    
    

The namespace support for the marshalling transformer requires an input channel, output channel and a reference to a marshaller. The optional result-type attribute can be used to control the type of result created, valid values are StringResult or DomResult (the default). Where the provided result types are not sufficient a reference to a custom implementation of ResultFactory can be provided as an alternative to setting the result-type attribute using the result-factory attribute. An optional result-transformer can also be specified in order to convert the created Result after marshalling.

<si-xml:marshalling-transformer
     input-channel="marshallingTransformerStringResultFactory"
     output-channel="output"
     marshaller="marshaller"
     result-type="StringResult" />
     
<si-xml:marshalling-transformer
    input-channel="marshallingTransformerWithResultTransformer"
    output-channel="output"
    marshaller="marshaller"
    result-transformer="resultTransformer" />
     
<bean id="resultTransformer"
      class="org.springframework.integration.xml.transformer.ResultToStringTransformer"/>

Namespace support for the XsltPayloadTransformer allows either a resource to be passed in in order to create the Templates instance or alternatively a precreated Templates instance can be passed in as a reference. In common with the marshalling transformer the type of the result output can be controlled by specifying either the result-factory or result-type attribute. A result-transfomer attribute can also be used to reference an implementation of ResultTransfomer where conversion of the result is required before sending.

<si-xml:xslt-transformer id="xsltTransformerWithResource"
    input-channel="withResourceIn"
    output-channel="output"
    xsl-resource="org/springframework/integration/xml/config/test.xsl"/>
<si-xml:xslt-transformer id="xsltTransformerWithTemplatesAndResultTransformer"
    input-channel="withTemplatesAndResultTransformerIn"
    output-channel="output"
    xsl-templates="templates"
    result-transformer="resultTransformer"/>