try {
      // define the type of schema - we use W3C:
      String schemaLang = "http://www.w3.org/2001/XMLSchema";

      // get validation driver:
      SchemaFactory factory = SchemaFactory.newInstance(schemaLang);

      // create schema by reading it from an XSD file:
      Schema schema = factory.newSchema(new StreamSource(new File("bpmnXMI.xsd")));
      Validator validator = schema.newValidator();

      // at last perform validation:
      validator.validate(new StreamSource(new File("bpmnModelTest.bpmn")));
      
    }catch (SAXException ex) {
      ex.printStackTrace();
    } catch (Exception ex) {
      ex.printStackTrace();
    }

org.xml.sax.SAXParseException: cvc-complex-type.3.2.2: Attribute 'xmi:version' is not allowed to appear in element 'bpmn:BpmnDiagram'.
	at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
	at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator$XSIErrorReporter.reportError(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.reportSchemaError(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.processAttributes(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.handleStartElement(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.startElement(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl$NSContentDriver.scanRootElementHook(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source)
	at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
	at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
	at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
	at com.sun.org.apache.xerces.internal.jaxp.validation.StreamValidatorHelper.validate(Unknown Source)
	at com.sun.org.apache.xerces.internal.jaxp.validation.ValidatorImpl.validate(Unknown Source)
	at javax.xml.validation.Validator.validate(Unknown Source)
	at it.eng.rspa.validator.Test.main(Test.java:33)