<p>XStream is a simple library to serialize objects to XML and back again.</p>
<p>Sometimes it can get tedious to call all those XStream
aliases/register converter methods or you might simply like the new
trend on configuring POJOs: Java annotations.</p>
<p>While using annotations if you ever got this exception the there might be a change that you forgot to call process annotation</p>
<pre> XStream stream = new XStream(new DomDriver());
stream.processAnnotations(YourClassName.class);</pre>
<p>Calling stream.processAnnotations(YourClassName.class); will clear down this exception.</p><br><br><div class="gmail_quote">On Tue, May 29, 2012 at 11:40 PM, Francois Rouaix <span dir="ltr"><<a href="mailto:francois.rouaix@gmail.com" target="_blank">francois.rouaix@gmail.com</a>></span> wrote:<br>
<blockquote style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid" class="gmail_quote">Folks,<div>I'm trying to use Drools in a mostly Java-less environment (rules are written in .drl files, facts will be inserted from XML files). I'm running into an issue where the XStream unmarshaller is unable to convert my XML to a BatchExecutionCommand because it cannot find the class for a type declared in the .drl file.</div>
<div>Is there any configuration required to make sure the XStream marshaller knows about the dynamically generated classes from the .drl?</div><div>I'd appreciated any clues. I cannot add POJO classes for my types due to the nature of the app.</div>
<div>Thanks.</div><div><br></div><div><br></div><div>DRL file</div><div>-----------</div><div><div>package com.example</div><div>declare Answers </div></div><div>....</div><div>end</div><div>/* some rules after this */</div>
<div>...</div><div><br></div><div>XML file</div><div>-----------</div><div><div><batch-execution></div><div> <insert></div><div> <com.example.Answers></div></div><div> ....</div><div><br></div>
<div>
<br></div><div>Runner code</div><div><div><span style="white-space:pre-wrap"> </span>public static void Run(String xmlFactsFile, String drlFilename)</div><div><span style="white-space:pre-wrap"> </span>{</div>
<div><span style="white-space:pre-wrap"> </span>// Compile the drl file</div><div><span style="white-space:pre-wrap"> </span>KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();</div>
<div><span style="white-space:pre-wrap"> </span>kbuilder.add( ResourceFactory.newFileResource(drlFilename),</div><div><span style="white-space:pre-wrap"> </span>ResourceType.DRL );</div>
<div><span style="white-space:pre-wrap"> </span>if ( kbuilder.hasErrors() ) {</div><div><span style="white-space:pre-wrap"> </span>System.err.println( kbuilder.getErrors().toString() );</div>
<div><span style="white-space:pre-wrap"> </span>throw new RuntimeException("Cannot compile \"" + drlFilename + "\"");</div><div><span style="white-space:pre-wrap"> </span>}</div>
<div><span style="white-space:pre-wrap"> </span></div><div><span style="white-space:pre-wrap"> </span>// kbase setup from the compiled rules</div><div><span style="white-space:pre-wrap"> </span>KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();</div>
<div><span style="white-space:pre-wrap"> </span>kbase.addKnowledgePackages( kbuilder.getKnowledgePackages() );</div><div><span style="white-space:pre-wrap"> </span></div><div><span style="white-space:pre-wrap"> </span>StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();</div>
<div><span style="white-space:pre-wrap"> </span>File facts = new File(xmlFactsFile);</div><div><span style="white-space:pre-wrap"> </span>BatchExecutionCommand command = (BatchExecutionCommand) BatchExecutionHelper.newXStreamMarshaller().fromXML(facts);</div>
<div><span style="white-space:pre-wrap"> </span>ExecutionResults bresults = ksession.execute(command);</div><div><span style="white-space:pre-wrap"> </span>System.out.println(BatchExecutionHelper.newXStreamMarshaller().toXML(bresults));</div>
<div><span style="white-space:pre-wrap"> </span>}</div><div>}</div></div><div><br></div><div>Error at runtime</div><div>----------------------</div><div><div>Exception in thread "main" com.thoughtworks.xstream.converters.ConversionException: com.example.Answers : com.example.Answers</div>
<div>---- Debugging information ----</div><div>message : com.example.Answers</div><div>cause-exception : com.thoughtworks.xstream.mapper.CannotResolveClassException</div><div>cause-message : com.example.Answers</div>
<div>class : org.drools.command.runtime.rule.InsertObjectCommand</div><div>required-type : org.drools.command.runtime.rule.InsertObjectCommand</div><div>converter-type : org.drools.runtime.help.impl.XStreamXML$InsertConverter</div>
<div>path : /batch-execution/insert/com.example.Answers</div><div>line number : 3</div><div>class[1] : org.drools.command.runtime.BatchExecutionCommandImpl</div><div>converter-type[1] : com.thoughtworks.xstream.converters.reflection.ReflectionConverter</div>
<div>version : null</div><div>-------------------------------</div><div> at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:79)</div><div> at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)</div>
<div> at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)</div><div> at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:50)</div><div>
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:318)</div><div> at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:230)</div>
<div> at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)</div><div> at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)</div>
<div> at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)</div><div> at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:50)</div><div>
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:134)</div><div> at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:32)</div>
<div> at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1035)</div><div> at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1019)</div><div> at com.thoughtworks.xstream.XStream.fromXML(XStream.java:930)</div>
<div> at com.intentsoft.RulesEngine.RulesExecution.Run(RulesExecution.java:34)</div><div> at com.intentsoft.RulesEngine.Main.main(Main.java:10)</div><div>Caused by: com.thoughtworks.xstream.mapper.CannotResolveClassException: com.example.Answers</div>
<div> at com.thoughtworks.xstream.mapper.DefaultMapper.realClass(DefaultMapper.java:56)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.DynamicProxyMapper.realClass(DynamicProxyMapper.java:55)</div>
<div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.PackageAliasingMapper.realClass(PackageAliasingMapper.java:88)</div><div>
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.ClassAliasingMapper.realClass(ClassAliasingMapper.java:79)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div>
<div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div>
<div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.ArrayMapper.realClass(ArrayMapper.java:74)</div>
<div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div>
<div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div>
<div> at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)</div><div> at com.thoughtworks.xstream.mapper.CachingMapper.realClass(CachingMapper.java:45)</div><div> at com.thoughtworks.xstream.core.util.HierarchicalStreams.readClassType(HierarchicalStreams.java:29)</div>
<div> at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.readItem(AbstractCollectionConverter.java:70)</div><div> at org.drools.runtime.help.impl.XStreamXML$InsertConverter.unmarshal(XStreamXML.java:135)</div>
<div> at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)</div><div> ... 16 more</div></div><div><br></div>
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<br></blockquote></div><br>