XPath/XSLT Conflict

Hi all. I'm attempting to create a Spring Integration flow involving an xpath-header-enricher and an xslt-transformer. The transformer works fine on its own, as does the header enricher. However, once I follow the header enricher with the transformer, I get a "failed to transform"/"content is not allowed in prolog" error.

That error is usually indicative of malformed XML somewhere or an encoding issue, but when the transformation works perfectly on its own, I can't possibly imagine that a header enricher would affect the payload (which is a Document) at all, let alone to the point where it would break it.

This leads me to believe that using the xpath-header-enricher introduces a parser which doesn't play nice with the transformer. I have Saxon as a dependency so I can use XSLT 2.0. I looked into the hierarchy and saw that Jaxen is an optional dependency to spring-xml (the WS version), but including it in my project didn't change anything.

Any ideas? Here's my configuration:

Code:

---

<int:gateway service-interface="com.domain.framework.event.gateway.EventGateway"
        id="eventGateway" default-request-channel="eventRouteAccessChainChannel"
        default-reply-channel="eventGatewayOutputChannel" />

<int-xml:xpath-expression id="eventTypeExp"
        expression="/emit:event/@eventType" namespace-map="namespaceMap" />

<int:chain input-channel="eventRouteAccessChainChannel">
        <int-xml:validating-filter schema-location="classpath:schemas/emitterEvent.xsd"
                discard-channel="eventErrorChannel" />
        <int-xml:xpath-header-enricher>
                <int-xml:header name="eventType" xpath-expression-ref="eventTypeExp" />
                <int-xml:header name="eventAll" xpath-expression="/" />
        </int-xml:xpath-header-enricher>
        <int:router default-output-channel="eventErrorChannel"
                expression="headers.eventType + 'RulesChannel'" />
</int:chain>

<int:service-activator input-channel="testRulesChannel"
        output-channel="eventRouteChainChannel" expression="@routingMap.get(headers.eventType)" />

<int:chain input-channel="eventRouteChainChannel"
        output-channel="eventGatewayOutputChannel">
        <int:splitter expression="payload" />
        <int:header-enricher>
                <int:header name="eventRoute" expression="payload" />
        </int:header-enricher>
        <int:service-activator expression="headers.eventAll" />
        <int-xml:xslt-transformer xsl-resource="xsl/emitterEvent-to-event-transformer.xsl" />
</int:chain>

---

I have wiretaps on my channels so I can see that my message is definitely passing through the flow, as it gets the correct headers/payload based on the other components.

Thanks.

Can you run with DEBUG level logging and compare the inbound message to the transformer on the works Vs. not works scenario?

Hi, Matt!

So, I see where is a problem.
I minimize your config to show it:

HTML Code:

---

<int-xml:xpath-header-enricher>
        <int-xml:header name="eventAll" xpath-expression="/" /> !!! HERE !!!
</int-xml:xpath-header-enricher>
<int:service-activator expression="headers.eventAll" />
<int-xml:xslt-transformer xsl-resource="xsl/emitterEvent-to-event-transformer.xsl" />

---

By default <xml:header> will be converted to the String, because:

Quote:

---

<xsd:attribute name="evaluation-type" default="STRING_RESULT">

---

So to fix your issue, just to make it like this:

HTML Code:

---

<int-xml:header name="eventAll" xpath-expression="/" evaluation-type="NODE_RESULT"/>

---

Take care,
Artem

Thanks, Artem. That worked. I also found that I could have used a regular header enricher with an expression of "payload" to get the same result, but I'm going with your idea so I can group all the headers I'm adding together.

Thanks again!