XSLT for-each-group not supported in Apache Camel? - apache-camel

Question

I'm trying to transform an XML using the for-each-group element as such:
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/orders">
<myElem>
<xsl:for-each-group select="order" group-by="identifier/value">
<xsl:sort select="current()/date" order="descending" />
<xsl:apply-templates select="current()" />
</xsl:for-each-group>
</myElem>
</xsl:template>
</xsl:stylesheet>
My source document:
<?xml version="1.0" encoding="UTF-8"?>
<orders>
<order>
<identifier>
<value>Order489</value>
</identifier>
<date>2016-08-10T15:39:16</date>
<customer>
<id>***</id>
<address>***</address>
</customer>
...
</order>
<order>
<identifier>
<value>Order490</value>
</identifier>
<date>2016-08-10T15:42:34</date>
<customer>
<id>***</id>
<address>***</address>
</customer>
...
</order>
</orders>
No matter what I do the transformed XML ends up with an empty root element.
I have included the camel-saxon dependency in my POM and the feature is installed in the Karaf container.
My endpoint:
<to uri="xslt:/xsl/foo.xsl?transformerFactoryClass=net.sf.saxon.TransformerFactoryImpl" />
I'm starting to think that this feature is not supported by the camel-saxon component. I find it strange that I'm not getting any errors until further down my route.
Update
I have now noticed that when I start my bundle I get the following stacktrace:
"select" attribute is not allowed on the xsl:for-each-group element!; Line#: 10; Column#: 99
javax.xml.transform.TransformerException: "select" attribute is not allowed on the xsl:for-each-group element!
at org.apache.xalan.processor.StylesheetHandler.error(StylesheetHandler.java:904)[:]
at org.apache.xalan.processor.StylesheetHandler.error(StylesheetHandler.java:947)[:]
at org.apache.xalan.processor.XSLTElementProcessor.setPropertiesFromAttributes(XSLTElementProcessor.java:347)[:]
at org.apache.xalan.processor.XSLTElementProcessor.setPropertiesFromAttributes(XSLTElementProcessor.java:267)[:]
at org.apache.xalan.processor.ProcessorLRE.startElement(ProcessorLRE.java:283)[:]
at org.apache.xalan.processor.StylesheetHandler.startElement(StylesheetHandler.java:623)[:]
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown Source)[:]
at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)[:]
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)[:]
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)[:]
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)[:]
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)[:]
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)[:]
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)[:]
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)[:]
at org.apache.xalan.processor.TransformerFactoryImpl.newTemplates(TransformerFactoryImpl.java:917)[:]
at org.apache.camel.builder.xml.XsltBuilder.setTransformerSource(XsltBuilder.java:360)
at org.apache.camel.component.xslt.XsltEndpoint.loadResource(XsltEndpoint.java:342)
at org.apache.camel.component.xslt.XsltEndpoint.doStart(XsltEndpoint.java:396)
at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)
at org.apache.camel.impl.DefaultCamelContext.startService(DefaultCamelContext.java:2869)
at org.apache.camel.impl.DefaultCamelContext.doAddService(DefaultCamelContext.java:1097)
at org.apache.camel.impl.DefaultCamelContext.addService(DefaultCamelContext.java:1058)
at org.apache.camel.impl.DefaultCamelContext.addService(DefaultCamelContext.java:1054)
at org.apache.camel.impl.DefaultCamelContext.getEndpoint(DefaultCamelContext.java:574)
at org.apache.camel.util.CamelContextHelper.getMandatoryEndpoint(CamelContextHelper.java:79)
at org.apache.camel.model.RouteDefinition.resolveEndpoint(RouteDefinition.java:200)
at org.apache.camel.impl.DefaultRouteContext.resolveEndpoint(DefaultRouteContext.java:107)
at org.apache.camel.impl.DefaultRouteContext.resolveEndpoint(DefaultRouteContext.java:113)
at org.apache.camel.model.SendDefinition.resolveEndpoint(SendDefinition.java:62)
at org.apache.camel.model.SendDefinition.createProcessor(SendDefinition.java:56)
at org.apache.camel.model.ProcessorDefinition.makeProcessorImpl(ProcessorDefinition.java:533)
at org.apache.camel.model.ProcessorDefinition.makeProcessor(ProcessorDefinition.java:494)
at org.apache.camel.model.ProcessorDefinition.addRoutes(ProcessorDefinition.java:219)
at org.apache.camel.model.RouteDefinition.addRoutes(RouteDefinition.java:1025)
at org.apache.camel.model.RouteDefinition.addRoutes(RouteDefinition.java:185)
at org.apache.camel.impl.DefaultCamelContext.startRoute(DefaultCamelContext.java:841)
at org.apache.camel.impl.DefaultCamelContext.startRouteDefinitions(DefaultCamelContext.java:2895)
at org.apache.camel.impl.DefaultCamelContext.doStartCamel(DefaultCamelContext.java:2618)
at org.apache.camel.impl.DefaultCamelContext.access$000(DefaultCamelContext.java:167)
at org.apache.camel.impl.DefaultCamelContext$2.call(DefaultCamelContext.java:2467)
at org.apache.camel.impl.DefaultCamelContext$2.call(DefaultCamelContext.java:2463)
at org.apache.camel.impl.DefaultCamelContext.doWithDefinedClassLoader(DefaultCamelContext.java:2486)
at org.apache.camel.impl.DefaultCamelContext.doStart(DefaultCamelContext.java:2463)
at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)
at org.apache.camel.impl.DefaultCamelContext.start(DefaultCamelContext.java:2432)
at org.apache.camel.blueprint.BlueprintCamelContext.start(BlueprintCamelContext.java:180)
at org.apache.camel.blueprint.BlueprintCamelContext.maybeStart(BlueprintCamelContext.java:212)
at org.apache.camel.blueprint.BlueprintCamelContext.serviceChanged(BlueprintCamelContext.java:150)
at org.apache.felix.framework.util.EventDispatcher.invokeServiceListenerCallback(EventDispatcher.java:943)
at org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:794)
at org.apache.felix.framework.util.EventDispatcher.fireServiceEvent(EventDispatcher.java:544)
at org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:4445)
at org.apache.felix.framework.Felix.registerService(Felix.java:3431)
at org.apache.felix.framework.BundleContextImpl.registerService(BundleContextImpl.java:346)
at org.apache.felix.framework.BundleContextImpl.registerService(BundleContextImpl.java:353)
at org.apache.camel.blueprint.BlueprintCamelContext.init(BlueprintCamelContext.java:100)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)[:1.8.0_101]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)[:1.8.0_101]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)[:1.8.0_101]
at java.lang.reflect.Method.invoke(Unknown Source)[:1.8.0_101]
at org.apache.aries.blueprint.utils.ReflectionUtils.invoke(ReflectionUtils.java:299)
at org.apache.aries.blueprint.container.BeanRecipe.invoke(BeanRecipe.java:956)
at org.apache.aries.blueprint.container.BeanRecipe.runBeanProcInit(BeanRecipe.java:712)
at org.apache.aries.blueprint.container.BeanRecipe.internalCreate2(BeanRecipe.java:824)
at org.apache.aries.blueprint.container.BeanRecipe.internalCreate(BeanRecipe.java:787)
at org.apache.aries.blueprint.di.AbstractRecipe$1.call(AbstractRecipe.java:79)
at java.util.concurrent.FutureTask.run(Unknown Source)[:1.8.0_101]
at org.apache.aries.blueprint.di.AbstractRecipe.create(AbstractRecipe.java:88)
at org.apache.aries.blueprint.container.BlueprintRepository.createInstances(BlueprintRepository.java:247)
at org.apache.aries.blueprint.container.BlueprintRepository.createAll(BlueprintRepository.java:183)
at org.apache.aries.blueprint.container.BlueprintContainerImpl.instantiateEagerComponents(BlueprintContainerImpl.java:682)
at org.apache.aries.blueprint.container.BlueprintContainerImpl.doRun(BlueprintContainerImpl.java:377)
at org.apache.aries.blueprint.container.BlueprintContainerImpl.run(BlueprintContainerImpl.java:269)
at org.apache.aries.blueprint.container.BlueprintExtender.createContainer(BlueprintExtender.java:294)
at org.apache.aries.blueprint.container.BlueprintExtender.createContainer(BlueprintExtender.java:263)
at org.apache.aries.blueprint.container.BlueprintExtender.modifiedBundle(BlueprintExtender.java:253)
at org.apache.aries.util.tracker.hook.BundleHookBundleTracker$Tracked.customizerModified(BundleHookBundleTracker.java:500)[17:org.apache.aries.util:1.1.0]
at org.apache.aries.util.tracker.hook.BundleHookBundleTracker$Tracked.customizerModified(BundleHookBundleTracker.java:433)[17:org.apache.aries.util:1.1.0]
at org.apache.aries.util.tracker.hook.BundleHookBundleTracker$AbstractTracked.track(BundleHookBundleTracker.java:725)[17:org.apache.aries.util:1.1.0]
at org.apache.aries.util.tracker.hook.BundleHookBundleTracker$Tracked.bundleChanged(BundleHookBundleTracker.java:463)[17:org.apache.aries.util:1.1.0]
at org.apache.aries.util.tracker.hook.BundleHookBundleTracker$BundleEventHook.event(BundleHookBundleTracker.java:422)
at org.apache.felix.framework.util.SecureAction.invokeBundleEventHook(SecureAction.java:1127)
at org.apache.felix.framework.util.EventDispatcher.createWhitelistFromHooks(EventDispatcher.java:696)
at org.apache.felix.framework.util.EventDispatcher.fireBundleEvent(EventDispatcher.java:484)
at org.apache.felix.framework.Felix.fireBundleEvent(Felix.java:4429)
at org.apache.felix.framework.Felix.startBundle(Felix.java:2100)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:976)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:963)
at org.apache.karaf.shell.osgi.RestartBundle.doExecute(RestartBundle.java:45)
at org.apache.karaf.shell.osgi.BundlesCommand.doExecute(BundlesCommand.java:37)
at org.apache.karaf.shell.console.OsgiCommandSupport.execute(OsgiCommandSupport.java:38)
at org.apache.felix.gogo.commands.basic.AbstractCommand.execute(AbstractCommand.java:35)
at sun.reflect.GeneratedMethodAccessor169.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)[:1.8.0_101]
at java.lang.reflect.Method.invoke(Unknown Source)[:1.8.0_101]
at org.apache.aries.proxy.impl.ProxyHandler$1.invoke(ProxyHandler.java:54)[19:org.apache.aries.proxy.impl:1.0.4]
at org.apache.aries.proxy.impl.ProxyHandler.invoke(ProxyHandler.java:119)[19:org.apache.aries.proxy.impl:1.0.4]
at org.apache.karaf.shell.console.commands.$BlueprintCommand796348771.execute(Unknown Source)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.felix.gogo.runtime.CommandProxy.execute(CommandProxy.java:78)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.felix.gogo.runtime.Closure.executeCmd(Closure.java:477)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.felix.gogo.runtime.Closure.executeStatement(Closure.java:403)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.felix.gogo.runtime.Pipe.run(Pipe.java:108)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:183)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:120)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.felix.gogo.runtime.CommandSessionImpl.execute(CommandSessionImpl.java:92)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.karaf.shell.console.jline.Console.run(Console.java:197)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
at org.apache.karaf.shell.console.jline.DelayedStarted.run(DelayedStarted.java:79)[38:org.apache.karaf.shell.console:2.4.0.redhat-621084]
So, am I missing a dependency somewhere or is this plainly not supported in Camel as of now?

Answer 1

The symptoms you describe suggest that the path expression otherElem is not selecting anything.
It's an odd path expression to find here, because if it does select anything it will only select one element (your context node is the root node "/", which can only have one element child), and if you've only got one element in a node-set then grouping it is rather pointless.
Show us your source document and your desired output, and we're more likely to be able to see where you've gone astray.
Later
You have now provided a source document and a stylesheet. After repairing your source document (the final end tag was wrong), the transformation produces the output:
<?xml version="1.0" encoding="UTF-8"?><myElem>
Order490
2016-08-10T15:42:34
***
***
...
Order489
2016-08-10T15:39:16
***
***
... </myElem>
Doesn't look very useful, but it's certainly not the "empty root element" that you allege.