diff options
Diffstat (limited to 'eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParser.java')
| -rw-r--r-- | eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParser.java | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParser.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParser.java new file mode 100644 index 00000000..2c715b94 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParser.java @@ -0,0 +1,226 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process; + +import java.io.IOException; +import java.io.InputStream; +import java.util.ArrayList; +import java.util.Iterator; +import java.util.List; +import java.util.Objects; + +import javax.xml.XMLConstants; +import javax.xml.namespace.QName; +import javax.xml.stream.XMLEventReader; +import javax.xml.stream.XMLInputFactory; +import javax.xml.stream.XMLStreamConstants; +import javax.xml.stream.XMLStreamException; +import javax.xml.stream.events.Attribute; +import javax.xml.stream.events.StartElement; +import javax.xml.stream.events.XMLEvent; +import javax.xml.stream.util.EventReaderDelegate; +import javax.xml.transform.stax.StAXSource; +import javax.xml.transform.stream.StreamSource; +import javax.xml.validation.Schema; +import javax.xml.validation.SchemaFactory; +import javax.xml.validation.Validator; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.xml.sax.SAXException; + +import at.gv.egiz.eaaf.core.impl.idp.process.model.EndEvent; +import at.gv.egiz.eaaf.core.impl.idp.process.model.ProcessDefinition; +import at.gv.egiz.eaaf.core.impl.idp.process.model.ProcessNode; +import at.gv.egiz.eaaf.core.impl.idp.process.model.StartEvent; +import at.gv.egiz.eaaf.core.impl.idp.process.model.TaskInfo; +import at.gv.egiz.eaaf.core.impl.idp.process.model.Transition; + +/** + * Parses an XML representation of a process definition as defined by the respective XML schema. + * <p/ + * The parser is thread-safe. + * @author tknall + * + */ +public class ProcessDefinitionParser { + + private static final String NS = "http://reference.e-government.gv.at/namespace/moa/process/definition/v1"; + + private static Logger log = LoggerFactory.getLogger(ProcessDefinitionParser.class); + + private static class LazyProcessDefinitionSchemaHolder { + private static final Schema PD_SCHEMA_INSTANCE; + static { + try (InputStream in = ProcessDefinitionParser.class.getResourceAsStream("/process/ProcessDefinition.xsd")) { + log.trace("Compiling process definition schema."); + SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI); + // schema is thread-safe + PD_SCHEMA_INSTANCE = factory.newSchema(new StreamSource(in)); + } catch (Exception e) { + throw new RuntimeException("Unable to compile process definition schema.", e); + } + } + } + + /** + * Parses an XML representation of a process definition. The representation is being validated in order to suffice + * the related XML schema. + * + * @param processDefinitionInputStream + * The process definition. + * @return A new process definition. + * @throws ProcessDefinitionParserException + * Thrown in case of error parsing the process definition. + */ + public ProcessDefinition parse(InputStream processDefinitionInputStream) throws ProcessDefinitionParserException { + XMLEventReader reader = null; + final ProcessDefinition pd = new ProcessDefinition(); + log.debug("Parsing and validating process definition."); + try { + + // Standard implementation of XMLInputFactory seems not to be thread-safe + XMLInputFactory inputFactory = XMLInputFactory.newInstance(); + reader = inputFactory.createXMLEventReader(processDefinitionInputStream); + + final List<StartElement> transitionElements = new ArrayList<>(); + final List<StartEvent> startEvents = new ArrayList<>(); + + reader = new EventReaderDelegate(reader) { + + @Override + public XMLEvent nextEvent() throws XMLStreamException { + XMLEvent event = super.nextEvent(); + + switch (event.getEventType()) { + case XMLStreamConstants.START_ELEMENT: + StartElement element = event.asStartElement(); + QName qname = element.getName(); + + if (NS.equals(qname.getNamespaceURI())) { + log.trace("Found process description element '{}'.", qname.getLocalPart()); + Attribute id = element.getAttributeByName(new QName("id")); + + switch (qname.getLocalPart()) { + case "ProcessDefinition": + if (id != null) { + pd.setId(id.getValue()); + } + break; + case "StartEvent": + StartEvent startEvent = new StartEvent(); + if (id != null) { + startEvent.setId(id.getValue()); + } + startEvents.add(startEvent); + break; + case "EndEvent": + EndEvent endEvent = new EndEvent(); + if (id != null) { + endEvent.setId(id.getValue()); + pd.getEndEvents().put(id.getValue(), endEvent); + } + break; + case "Transition": + transitionElements.add(element); + break; + case "Task": + TaskInfo taskInfo = new TaskInfo(); + if (id != null) { + taskInfo.setId(id.getValue()); + pd.getTaskInfos().put(id.getValue(), taskInfo); + } + Attribute async = element.getAttributeByName(new QName("async")); + if (async != null) { + taskInfo.setAsync(Boolean.valueOf(async.getValue())); + } + Attribute implementingClass = element.getAttributeByName(new QName("class")); + if (implementingClass != null) { + taskInfo.setTaskImplementingClass(implementingClass.getValue()); + } + break; + } + + } + + break; + } + + return event; + } + + }; + + // validator is not thread-safe + Validator validator = LazyProcessDefinitionSchemaHolder.PD_SCHEMA_INSTANCE.newValidator(); + validator.validate(new StAXSource(reader)); + log.trace("Process definition successfully schema validated."); + + // perform some basic checks + log.trace("Building model and performing some plausibility checks."); + if (startEvents.size() != 1) { + throw new ProcessDefinitionParserException("A ProcessDefinition must contain exactly one single StartEvent."); + } + pd.setStartEvent(startEvents.get(0)); + + // link transitions + Iterator<StartElement> transitions = transitionElements.iterator(); + while (transitions.hasNext()) { + StartElement element = transitions.next(); + Transition transition = new Transition(); + Attribute id = element.getAttributeByName(new QName("id")); + if (id != null) { + transition.setId(id.getValue()); + } + Attribute conditionExpression = element.getAttributeByName(new QName("conditionExpression")); + if (conditionExpression != null) { + transition.setConditionExpression(conditionExpression.getValue()); + } + Attribute from = element.getAttributeByName(new QName("from")); + if (from != null) { + ProcessNode fromNode = pd.getProcessNode(from.getValue()); + if (fromNode == null) { + throw new ProcessDefinitionParserException("Transition's 'from'-attribute refers to a non-existing event or task '" + from.getValue() + '.'); + } + if (fromNode instanceof EndEvent) { + throw new ProcessDefinitionParserException("Transition cannot start from end event."); + } + transition.setFrom(fromNode); + fromNode.getOutgoingTransitions().add(transition); + } + Attribute to = element.getAttributeByName(new QName("to")); + if (to != null) { + ProcessNode toNode = pd.getProcessNode(to.getValue()); + if (toNode == null) { + throw new ProcessDefinitionParserException("Transition's 'to'-attribute refers to a non-existing event or task '" + to.getValue() + '.'); + } + transition.setTo(toNode); + toNode.getIncomingTransitions().add(transition); + } + if (transition.getConditionExpression() == null && Objects.equals(transition.getFrom(), transition.getTo())) { + throw new ProcessDefinitionParserException("Transition's 'from' equals its 'to'. Since no 'conditionExpression' has been set this will cause a loop."); + } + } + log.debug("Process definition '{}' successfully parsed.", pd.getId()); + return pd; + + } catch (ProcessDefinitionParserException e) { + throw e; + } catch (XMLStreamException|IOException e) { + throw new ProcessDefinitionParserException("Unable to read process definition from inputstream.", e); + } catch (SAXException e) { + throw new ProcessDefinitionParserException("Schema validation of process description failed.", e); + } catch (Exception e) { + throw new ProcessDefinitionParserException("Internal error creating process definition from inputstream.", e); + } finally { + if (reader != null) { + try { + reader.close(); + } catch (XMLStreamException e) { + // error freeing resources + } + } + } + } + +} |