diff options
Diffstat (limited to 'eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process')
20 files changed, 2180 insertions, 0 deletions
diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ExecutionContextImpl.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ExecutionContextImpl.java new file mode 100644 index 00000000..05fe030d --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ExecutionContextImpl.java @@ -0,0 +1,81 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process; + +import java.io.Serializable; +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; +import java.util.Set; + +import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext; + +/** + * ExecutionContext implementation, related to a certain process instance. + * + * @author tknall + * + */ +public class ExecutionContextImpl implements ExecutionContext { + + private static final long serialVersionUID = 1L; + + private Map<String, Serializable> ctxData = Collections.synchronizedMap(new HashMap<String, Serializable>()); + + private String processInstanceId; + + /** + * Creates a new instance. + */ + public ExecutionContextImpl() { + } + + /** + * Creates a new instance and associated it with a certain process instance. + */ + public ExecutionContextImpl(String processInstanceId) { + this.processInstanceId = processInstanceId; + } + + @Override + public void setProcessInstanceId(String processInstanceId) { + this.processInstanceId = processInstanceId; + } + + @Override + public String getProcessInstanceId() { + return processInstanceId; + } + + @Override + public Serializable get(String key) { + return ctxData.get(key); + } + + @Override + public Serializable remove(String key) { + return ctxData.remove(key); + } + + @Override + public void put(String key, Serializable object) { + ctxData.put(key, object); + } + + @Override + public Set<String> keySet() { + return Collections.unmodifiableSet(ctxData.keySet()); + } + + @Override + public String toString() { + StringBuilder builder = new StringBuilder(); + builder.append("ExecutionContextImpl ["); + builder.append("id=").append(processInstanceId); + builder.append(", variables="); + builder.append(ctxData.keySet()); + builder.append("]"); + return builder.toString(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ExpressionEvaluationContextImpl.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ExpressionEvaluationContextImpl.java new file mode 100644 index 00000000..5a85487f --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ExpressionEvaluationContextImpl.java @@ -0,0 +1,46 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process; + +import java.io.Serializable; +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; +import java.util.Set; + +import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext; +import at.gv.egiz.eaaf.core.api.idp.process.ExpressionEvaluationContext; + +/** + * Context implementation used for expression evaluation only. + * + * @author tknall + * + */ +public class ExpressionEvaluationContextImpl implements ExpressionEvaluationContext { + + private static final long serialVersionUID = 1L; + + private Map<String, Serializable> ctxData; + + /** + * Creates a new instance and initializes it with data from a given process instance. + * + * @param processInstance + * The process instance. + */ + ExpressionEvaluationContextImpl(ProcessInstance processInstance) { + ExecutionContext executionContext = processInstance.getExecutionContext(); + Set<String> keys = executionContext.keySet(); + ctxData = Collections.synchronizedMap(new HashMap<String, Serializable>(keys.size())); + for (String key : keys) { + ctxData.put(key, executionContext.get(key)); + } + } + + @Override + public Map<String, Serializable> getCtx() { + return Collections.unmodifiableMap(ctxData); + } + +} 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 + } + } + } + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParserException.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParserException.java new file mode 100644 index 00000000..1ea811c6 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessDefinitionParserException.java @@ -0,0 +1,37 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process; + +/** + * Exception thrown in case of error parsing a process definition. + * + * @author tknall + * + */ +public class ProcessDefinitionParserException extends Exception { + + private static final long serialVersionUID = 1L; + + /** + * Creates a new parser exception providing a {@code message} describing the reason and the {@code cause}. + * + * @param message + * The message. + * @param cause + * The cause. + */ + public ProcessDefinitionParserException(String message, Throwable cause) { + super(message, cause); + } + + /** + * Creates a new parser exception providing a {@code message} describing the reason. + * + * @param message + * The message. + */ + public ProcessDefinitionParserException(String message) { + super(message); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessEngineImpl.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessEngineImpl.java new file mode 100644 index 00000000..b5028542 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessEngineImpl.java @@ -0,0 +1,424 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process; + +import java.io.InputStream; +import java.io.Serializable; +import java.util.HashMap; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; + +import org.apache.commons.collections4.CollectionUtils; +import org.apache.commons.collections4.Predicate; +import org.apache.commons.lang3.StringUtils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.slf4j.MDC; +import org.springframework.beans.factory.annotation.Autowired; +import org.springframework.context.ApplicationContext; + +import at.gv.egiz.eaaf.core.api.IRequest; +import at.gv.egiz.eaaf.core.api.data.EAAFConstants; +import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext; +import at.gv.egiz.eaaf.core.api.idp.process.ExpressionEvaluationContext; +import at.gv.egiz.eaaf.core.api.idp.process.ExpressionEvaluator; +import at.gv.egiz.eaaf.core.api.idp.process.ProcessEngine; +import at.gv.egiz.eaaf.core.api.idp.process.ProcessInstanceStoreDAO; +import at.gv.egiz.eaaf.core.api.idp.process.Task; +import at.gv.egiz.eaaf.core.exceptions.EAAFException; +import at.gv.egiz.eaaf.core.exceptions.ProcessExecutionException; +import at.gv.egiz.eaaf.core.impl.idp.process.dao.ProcessInstanceStore; +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; + +/** + * Process engine implementation allowing starting and continuing processes as well as providing means for cleanup actions. + */ +public class ProcessEngineImpl implements ProcessEngine { + + private Logger log = LoggerFactory.getLogger(getClass()); + + @Autowired ProcessInstanceStoreDAO piStoreDao; + @Autowired ApplicationContext context; + + private ProcessDefinitionParser pdp = new ProcessDefinitionParser(); + + private Map<String, ProcessDefinition> processDefinitions = new ConcurrentHashMap<String, ProcessDefinition>(); + + private final static String MDC_CTX_PI_NAME = "processInstanceId"; + private final static String MDC_CTX_TASK_NAME = "taskId"; + + private ExpressionEvaluator transitionConditionExpressionEvaluator; + + @Override + public void registerProcessDefinition(ProcessDefinition processDefinition) { + log.info("Registering process definition '{}'.", processDefinition.getId()); + processDefinitions.put(processDefinition.getId(), processDefinition); + } + + @Override + public String registerProcessDefinition(InputStream processDefinitionInputStream) throws ProcessDefinitionParserException{ + ProcessDefinition pd = pdp.parse(processDefinitionInputStream); + registerProcessDefinition(pd); + return pd.getId(); + } + + /** + * Sets the process definitions. + * + * @param processDefinitions + * The process definitions. + * @throws IllegalArgumentException + * In case the process definitions contain definitions with the same identifier. + */ + public void setProcessDefinitions(Iterable<ProcessDefinition> processDefinitions) { + this.processDefinitions.clear(); + for (ProcessDefinition pd : processDefinitions) { + if (this.processDefinitions.containsKey(pd.getId())) { + throw new IllegalArgumentException("Duplicate process definition identifier '" + pd.getId() + "'."); + } + registerProcessDefinition(pd); + } + } + + /** + * Sets an expression evaluator that should be used to process transition condition expressions. + * @param transitionConditionExpressionEvaluator The expression evaluator. + */ + public void setTransitionConditionExpressionEvaluator( + ExpressionEvaluator transitionConditionExpressionEvaluator) { + this.transitionConditionExpressionEvaluator = transitionConditionExpressionEvaluator; + } + + + @Override + public String createProcessInstance(String processDefinitionId, ExecutionContext executionContext) throws ProcessExecutionException { + // look for respective process definition + ProcessDefinition pd = processDefinitions.get(processDefinitionId); + if (pd == null) { + throw new ProcessExecutionException("Unable to find process definition for process '" + processDefinitionId + "'."); + } + // create and keep process instance + ProcessInstance pi = new ProcessInstance(pd, executionContext); + log.info("Creating process instance from process definition '{}': {}", processDefinitionId, pi.getId()); + + try { + saveOrUpdateProcessInstance(pi); + + } catch (EAAFException e) { + throw new ProcessExecutionException("Unable to persist process instance.", e); + } + + return pi.getId(); + } + + @Override + public String createProcessInstance(String processDefinitionId) throws ProcessExecutionException { + return createProcessInstance(processDefinitionId, null); + } + + @Override + public void start(IRequest pendingReq) throws ProcessExecutionException { + try { + if (StringUtils.isEmpty(pendingReq.getProcessInstanceId())) { + log.error("Pending-request with id:" + pendingReq.getPendingRequestId() + + " includes NO 'ProcessInstanceId'"); + throw new ProcessExecutionException("Pending-request with id:" + pendingReq.getPendingRequestId() + + " includes NO 'ProcessInstanceId'"); + } + + ProcessInstance pi = loadProcessInstance(pendingReq.getProcessInstanceId()); + + if (pi == null ) { + throw new ProcessExecutionException("Process instance '" + pendingReq.getProcessInstanceId() + "' does not exist."); + + } + + MDC.put(MDC_CTX_PI_NAME, pi.getId()); + + if (!ProcessInstanceState.NOT_STARTED.equals(pi.getState())) { + throw new ProcessExecutionException("Process instance '" + pi.getId() + "' has already been started (current state is " + pi.getState() + ")."); + } + log.info("Starting process instance '{}'.", pi.getId()); + // execute process + pi.setState(ProcessInstanceState.STARTED); + execute(pi, pendingReq); + + //store ProcessInstance if it is not already ended + if (!ProcessInstanceState.ENDED.equals(pi.getState())) + saveOrUpdateProcessInstance(pi); + + } catch (EAAFException e) { + throw new ProcessExecutionException("Unable to load/save process instance.", e); + + } finally { + MDC.remove(MDC_CTX_PI_NAME); + } + } + + @Override + public void signal(IRequest pendingReq) throws ProcessExecutionException { + + try { + if (StringUtils.isEmpty(pendingReq.getProcessInstanceId())) { + log.error("Pending-request with id:" + pendingReq.getPendingRequestId() + + " includes NO 'ProcessInstanceId'"); + throw new ProcessExecutionException("Pending-request with id:" + pendingReq.getPendingRequestId() + + " includes NO 'ProcessInstanceId'"); + } + + ProcessInstance pi = loadProcessInstance(pendingReq.getProcessInstanceId()); + + if (pi == null ) { + throw new ProcessExecutionException("Process instance '" + pendingReq.getProcessInstanceId() + "' does not exist."); + + } + + MDC.put(MDC_CTX_PI_NAME, pi.getId()); + + if (!ProcessInstanceState.SUSPENDED.equals(pi.getState())) { + throw new ProcessExecutionException("Process instance '" + pi.getId() + "' has not been suspended (current state is " + pi.getState() + ")."); + } + + log.info("Waking up process instance '{}'.", pi.getId()); + pi.setState(ProcessInstanceState.STARTED); + + //put pending-request ID on execution-context because it could be changed + pi.getExecutionContext().put(EAAFConstants.PARAM_HTTP_TARGET_PENDINGREQUESTID, pendingReq.getPendingRequestId()); + + execute(pi, pendingReq); + + //store ProcessInstance if it is not already ended + if (!ProcessInstanceState.ENDED.equals(pi.getState())) + saveOrUpdateProcessInstance(pi); + + } catch (EAAFException e) { + throw new ProcessExecutionException("Unable to load/save process instance.", e); + + } finally { + MDC.remove(MDC_CTX_PI_NAME); + } + } + + + /** + * Instantiates a task implementation given by a {@link TaskInfo}. + * @param ti The task info. + * @return A Task implementation or {@code null} if the task info does not reference any task implementing classes. + * @throws ProcessExecutionException Thrown in case of error (when the referenced class does not implement {@link Task} for instance). + */ + private Task createTaskInstance(TaskInfo ti) throws ProcessExecutionException { + String clazz = StringUtils.trimToNull(ti.getTaskImplementingClass()); + Task task = null; + + if (clazz != null) { + log.debug("Instantiating task implementing class '{}'.", clazz); + Object instanceClass = null; + try { + instanceClass = context.getBean(clazz); + + } catch (Exception e) { + throw new ProcessExecutionException("Unable to get class '" + clazz + "' associated with task '" + ti.getId() + "' .", e); + + } + if (instanceClass == null || !(instanceClass instanceof Task)) { + throw new ProcessExecutionException("Class '" + clazz + "' associated with task '" + ti.getId() + "' is not assignable to " + Task.class.getName() + "."); + + } + try { + task = (Task) instanceClass; + + } catch (Exception e) { + throw new ProcessExecutionException("Unable to instantiate class '" + clazz + "' associated with task '" + ti.getId() + "' .", e); + } + } + + return task; + } + + /** + * Starts/executes a given process instance. + * @param pi The process instance. + * @param pendingReq + * @throws ProcessExecutionException Thrown in case of error. + */ + private void execute(final ProcessInstance pi, IRequest pendingReq) throws ProcessExecutionException { + if (ProcessInstanceState.ENDED.equals(pi.getState())) { + throw new ProcessExecutionException("Process for instance '" + pi.getId() + "' has already been ended."); + } + ProcessDefinition pd = pi.getProcessDefinition(); + ProcessNode processNode = pd.getProcessNode(pi.getNextId()); + log.debug("Processing node '{}'.", processNode.getId()); + + // distinguish process node types StartEvent, TaskInfo and EndEvent + + if (processNode instanceof TaskInfo) { + // TaskInfo types need to be executed + TaskInfo ti = (TaskInfo) processNode; + MDC.put(MDC_CTX_TASK_NAME, ti.getId()); + try { + log.info("Processing task '{}'.", ti.getId()); + Task task = createTaskInstance(ti); + if (task != null) { + try { + log.info("Executing task implementation for task '{}'.", ti.getId()); + log.debug("Execution context before task execution: {}", pi.getExecutionContext().keySet()); + pendingReq = task.execute(pendingReq, pi.getExecutionContext()); + log.info("Returned from execution of task '{}'.", ti.getId()); + log.debug("Execution context after task execution: {}", pi.getExecutionContext().keySet()); + } catch (Throwable t) { + throw new ProcessExecutionException("Error executing task '" + ti.getId() + "'.", t); + } + } else { + log.debug("No task implementing class set."); + } + } finally { + MDC.remove(MDC_CTX_TASK_NAME); + } + + } else if (processNode instanceof EndEvent) { + log.info("Finishing process instance '{}'.", pi.getId()); + + try { + piStoreDao.remove(pi.getId()); + + } catch (EAAFException e) { + throw new ProcessExecutionException("Unable to remove process instance.", e); + + } + pi.setState(ProcessInstanceState.ENDED); + log.debug("Final process context: {}", pi.getExecutionContext().keySet()); + return; + } + + final ExpressionEvaluationContext expressionContext = new ExpressionEvaluationContextImpl(pi); + + // traverse pointer + Transition t = CollectionUtils.find(processNode.getOutgoingTransitions(), new Predicate<Transition>() { + @Override + public boolean evaluate(Transition transition) { + if (transitionConditionExpressionEvaluator != null && transition.getConditionExpression() != null) { + log.trace("Evaluating transition expression '{}'.", transition.getConditionExpression()); + return transitionConditionExpressionEvaluator.evaluate(expressionContext, transition.getConditionExpression()); + } + return true; + } + }); + if (t == null) { + throw new ProcessExecutionException("No valid transition starting from process node '" + processNode.getId()+ "'."); + } + log.trace("Found suitable transition: {}", t); + // update pointer + log.trace("Shifting process token from '{}' to '{}'.", pi.getNextId(), t.getTo().getId()); + pi.setNextId(t.getTo().getId()); + + // inspect current task + if (t.getTo() instanceof TaskInfo && (((TaskInfo) t.getTo()).isAsync())) { + // immediately return in case of asynchonous task + log.info("Suspending process instance '{}' for asynchronous task '{}'.", pi.getId(), t.getTo().getId()); + pi.setState(ProcessInstanceState.SUSPENDED); + return; + } + + // continue execution in case of StartEvent or Task + if (processNode instanceof StartEvent || processNode instanceof TaskInfo) { + execute(pi, pendingReq); + } + } + + @Override + public ProcessInstance getProcessInstance(String processInstanceId) { + + ProcessInstance processInstance; + try { + processInstance = loadProcessInstance(processInstanceId); + + } catch (EAAFException e) { + throw new RuntimeException("The process instance '" + processInstanceId + "' could not be retrieved.", e); + } + + if (processInstance == null) { + throw new IllegalArgumentException("The process instance '" + processInstanceId + "' does not/no longer exist."); + } + + return processInstance; + } + + /** + * Persists a {@link ProcessInstance} to the database. + * @param processInstance The object to persist. + * @throws MOADatabaseException Thrown if an error occurs while accessing the database. + */ + private void saveOrUpdateProcessInstance(ProcessInstance processInstance) throws EAAFException { + ProcessInstanceStore store = new ProcessInstanceStore(); + + ExecutionContext ctx = processInstance.getExecutionContext(); + + Map<String, Serializable> ctxData = new HashMap<String, Serializable>(); + for (String key : ctx.keySet()) { + ctxData.put(key, ctx.get(key)); + } + store.setExecutionContextData(ctxData); + + store.setNextTaskId(processInstance.getNextId()); + store.setProcessDefinitionId(processInstance.getProcessDefinition().getId()); + + store.setProcessInstanceId(processInstance.getId()); + store.setProcessState(processInstance.getState()); + + piStoreDao.saveOrUpdate(store); + } + + /** + * Load a {@link ProcessInstance} with a certain id from the database. + * @param processInstanceId The process instance id + * @return The process instance corresponding to the id or {@code null} if no such object is found. + * @throws MOADatabaseException Thrown if an error occurs while accessing the database. + */ + private ProcessInstance loadProcessInstance(String processInstanceId) throws EAAFException { + + ProcessInstanceStore piStore = piStoreDao.load(processInstanceId); + + if (piStore == null) { + return null; + } + + ExecutionContext executionContext = new ExecutionContextImpl(piStore.getProcessInstanceId()); + + Map<String, Serializable> executionContextData = piStore.getExecutionContextData(); + for (String key : executionContextData.keySet()) { + executionContext.put(key, executionContextData.get(key)); + } + + ProcessInstance pi = new ProcessInstance(processDefinitions.get(piStore.getProcessDefinitionId()), executionContext); + pi.setNextId(piStore.getNextTaskId()); + pi.setState(piStore.getProcessState()); + + return pi; + } + + /* (non-Javadoc) + * @see at.gv.egovernment.moa.id.process.ProcessEngine#deleteProcessInstance(java.lang.String) + */ + @Override + public void deleteProcessInstance(String processInstanceId) throws ProcessExecutionException { + if (StringUtils.isEmpty(processInstanceId)) { + throw new ProcessExecutionException("Unable to remove process instance: ProcessInstanceId is empty"); + + } + + try { + piStoreDao.remove(processInstanceId); + + } catch (EAAFException e) { + throw new ProcessExecutionException("Unable to remove process instance.", e); + + } + + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessInstance.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessInstance.java new file mode 100644 index 00000000..ab6f7916 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessInstance.java @@ -0,0 +1,166 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process; + +import java.io.Serializable; +import java.util.Date; + +import org.apache.commons.lang3.RandomStringUtils; +import org.apache.commons.lang3.time.DurationFormatUtils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext; +import at.gv.egiz.eaaf.core.impl.idp.process.model.ProcessDefinition; +import at.gv.egiz.eaaf.core.impl.idp.process.support.SecureRandomHolder; + +/** + * Represents a process being executed. The process instance provides information about the process and its state. + * + * @author tknall + * + */ +public class ProcessInstance implements Serializable { + + private static final long serialVersionUID = 1L; + private static final int RND_ID_LENGTH = 22; + + private ProcessDefinition processDefinition; + private String nextId; + private Date lru; + private ExecutionContext executionContext; + private ProcessInstanceState state = ProcessInstanceState.NOT_STARTED; + + private Logger log = LoggerFactory.getLogger(getClass()); + + /** + * Creates a new process instance, based on a given process definition and a + * given execution context. If the given execution context is {@code null} a new execution context will be created.<p/> + * The process instance id of the execution context will be newly generated if it is {@code null} in the execution context. + * + * @param processDefinition + * The process definition. + * @param executionContext + * The execution context (may be {@code null}). If {@code null} a new execution context will be created internally. + */ + ProcessInstance(ProcessDefinition processDefinition, ExecutionContext executionContext) { + this.processDefinition = processDefinition; + nextId = processDefinition.getStartEvent().getId(); + if (executionContext == null) { + executionContext = new ExecutionContextImpl(); + } + if (executionContext.getProcessInstanceId() == null) { + String pdIdLocalPart = RandomStringUtils.random(RND_ID_LENGTH, 0, 0, true, true, null, + SecureRandomHolder.getInstance()); + executionContext.setProcessInstanceId(this.processDefinition.getId() + "-" + pdIdLocalPart); + } else { + log.debug("Using process instance id from execution context."); + } + log.debug("Creating process instance with id '{}'.", executionContext.getProcessInstanceId()); + this.executionContext = executionContext; + touch(); + } + + /** + * Returns the underlying process definition. + * + * @return The underlying process definition. + */ + ProcessDefinition getProcessDefinition() { + touch(); + return processDefinition; + } + + /** + * Returns the id of the process node to be executed next. + * + * @return The process node pointer indicating the process node to be executed next. + */ + public String getNextId() { + touch(); + return nextId; + } + + /** + * Sets the internal pointer to the process node to be executed next. + * + * @param nextId + * The process node id to be executed next. + */ + void setNextId(String nextId) { + touch(); + this.nextId = nextId; + } + + /** + * Returns the current state of the process instance. + * + * @return The current state. + */ + public ProcessInstanceState getState() { + touch(); + return state; + } + + /** + * Sets the current state of the process instance. + * + * @param state + * The current state. + */ + void setState(ProcessInstanceState state) { + touch(); + this.state = state; + } + + public String getId() { + touch(); + return executionContext.getProcessInstanceId(); + } + + /** + * Updates the last recently used date of the process instance. + */ + private void touch() { + lru = new Date(); + } + + /** + * Returns the date the process instance has been accessed last. + * + * @return The last recently used date. + */ + Date getLru() { + return lru; + } + + /** + * Returns the associated execution context. + * @return The execution context (never {@code null}). + */ + public ExecutionContext getExecutionContext() { + touch(); + return executionContext; + } + + @Override + public String toString() { + StringBuilder builder = new StringBuilder(); + builder.append("ProcessInstance ["); + builder.append("id=").append(executionContext.getProcessInstanceId()); + builder.append(", idle since=").append( + DurationFormatUtils.formatDurationWords(new Date().getTime() - this.lru.getTime(), true, true)); + if (processDefinition != null) { + builder.append(", processDefinition.id="); + builder.append(processDefinition.getId()); + } + if (nextId != null) { + builder.append(", nextId="); + builder.append(nextId); + } + builder.append(", executionContext=").append(executionContext); + builder.append("]"); + return builder.toString(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessInstanceState.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessInstanceState.java new file mode 100644 index 00000000..cfb5479b --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/ProcessInstanceState.java @@ -0,0 +1,32 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process; + +/** + * Represents a certain process instance state. + * @author tknall + * + */ +public enum ProcessInstanceState { + + /** + * Indicates that the process with this process instance has not yet been started. + */ + NOT_STARTED, + + /** + * Indicates that the process is currently running. + */ + STARTED, + + /** + * Indicates that the process has been suspended until being waken up by someonce calling {@code signal}. + */ + SUSPENDED, + + /** + * Indicates that the process has been completed. + */ + ENDED + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/dao/ProcessInstanceStore.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/dao/ProcessInstanceStore.java new file mode 100644 index 00000000..1ac65e10 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/dao/ProcessInstanceStore.java @@ -0,0 +1,75 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.dao; + +import java.io.Serializable; +import java.util.Map; + +import at.gv.egiz.eaaf.core.impl.idp.process.ProcessInstanceState; + +public class ProcessInstanceStore implements Serializable{ + + private static final long serialVersionUID = -6147519767313903808L; + + /** + * A process instance identifier qualifies as natural primary key by satisfying these requirements + * ("unique, constant, required"): + * <ul> + * <li>unique value</li> + * <li>never changes (immutable)</li> + * <li>never {@code null}</li> + * </ul> + */ + + private String processInstanceId; + + private String processDefinitionId; + + private String nextTaskId; + + private ProcessInstanceState processState; + + private Map<String, Serializable> executionContextData; + + public String getProcessInstanceId() { + return processInstanceId; + } + + public String getProcessDefinitionId() { + return processDefinitionId; + } + + public String getNextTaskId() { + return nextTaskId; + } + + public ProcessInstanceState getProcessState() { + return processState; + } + + @SuppressWarnings("unchecked") + public Map<String, Serializable> getExecutionContextData() { + return executionContextData; + } + + public void setProcessInstanceId(String processInstanceId) { + this.processInstanceId = processInstanceId; + } + + public void setProcessDefinitionId(String processDefinitionId) { + this.processDefinitionId = processDefinitionId; + } + + public void setNextTaskId(String nextTaskId) { + this.nextTaskId = nextTaskId; + } + + public void setProcessState(ProcessInstanceState processState) { + this.processState = processState; + } + + public void setExecutionContextData(Map<String, Serializable> executionContextData) { + this.executionContextData = executionContextData; + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/dao/ProcessInstanceStoreDAOImpl.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/dao/ProcessInstanceStoreDAOImpl.java new file mode 100644 index 00000000..be80a629 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/dao/ProcessInstanceStoreDAOImpl.java @@ -0,0 +1,73 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.dao; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.springframework.beans.factory.annotation.Autowired; +import org.springframework.stereotype.Service; + +import at.gv.egiz.eaaf.core.api.idp.process.ProcessInstanceStoreDAO; +import at.gv.egiz.eaaf.core.api.storage.ITransactionStorage; +import at.gv.egiz.eaaf.core.exceptions.EAAFException; + +/** + * Database backed implementation of the {@link ProcessInstanceStoreDAO} + * interface. + */ +@Service("ProcessInstanceStoreage") +public class ProcessInstanceStoreDAOImpl implements ProcessInstanceStoreDAO { + + private Logger log = LoggerFactory.getLogger(getClass()); + + @Autowired ITransactionStorage transactionStorage; + + @Override + public void saveOrUpdate(ProcessInstanceStore pIStore) throws EAAFException { + try { + transactionStorage.put(pIStore.getProcessInstanceId(), pIStore, -1); + log.debug("Store process instance with='{}' in the database.", pIStore.getProcessInstanceId()); + + } catch (EAAFException e) { + log.warn("ProcessInstanceStore could not be persisted to the database."); + throw e; + } + } + + @Override + public ProcessInstanceStore load(String processInstanceId) throws EAAFException { + log.debug("Retrieve the ProcessInstanceStore for id='{}' from the database.", processInstanceId); + ProcessInstanceStore result = null; + try { + result = transactionStorage.get(processInstanceId, ProcessInstanceStore.class); + + } catch (Exception e) { + log.error("There are multiple persisted processes with the same process instance id '{}'", + processInstanceId); + + throw e; + } + + if (result != null) { + log.debug("Found process instance store for instance '{}'.", processInstanceId); + + } else { + log.debug("Unable to find process instance store for instance '{}'.", processInstanceId); + + } + + return result; + } + + @Override + public void remove(String processInstanceId) throws EAAFException { + + log.debug("Delete the ProcessInstanceStore for id='{}' from the database.", processInstanceId); + + if (transactionStorage.containsKey(processInstanceId)) + transactionStorage.remove(processInstanceId); + else + log.trace("ProcessInstanceStore for id='{}' was not found and could therefore not be deleted.", processInstanceId); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/EndEvent.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/EndEvent.java new file mode 100644 index 00000000..a8b757e3 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/EndEvent.java @@ -0,0 +1,44 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.model; + +import java.io.Serializable; + +import org.apache.commons.collections4.CollectionUtils; + +/** + * Represents an end event. Process execution terminates when an end event is reached. + * + * @author tknall + */ +public class EndEvent extends ProcessNode implements Serializable { + + private static final long serialVersionUID = 1L; + + @Override + public String toString() { + StringBuilder builder = new StringBuilder(); + builder.append("EndEvent ["); + if (getId() != null) { + builder.append("id="); + builder.append(getId()); + } + if (CollectionUtils.isNotEmpty(getIncomingTransitions())) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("incomingTransitions="); + builder.append(getIncomingTransitions()); + } + if (CollectionUtils.isNotEmpty(getOutgoingTransitions())) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("outgoingTransitions="); + builder.append(getOutgoingTransitions()); + } + builder.append("]"); + return builder.toString(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/ProcessDefinition.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/ProcessDefinition.java new file mode 100644 index 00000000..af4c0a1f --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/ProcessDefinition.java @@ -0,0 +1,160 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.model; + +import java.util.LinkedHashMap; +import java.util.Map; +import java.util.Objects; + +import at.gv.egiz.eaaf.core.impl.idp.process.ProcessDefinitionParser; + +/** + * Represents a single process definition containing + * <ul> + * <li>a {@link StartEvent},</li> + * <li>one or more {@linkplain TaskInfo Tasks},</li> + * <li>one or more {@linkplain EndEvent EndEvents} and</li> + * <li>some {@linkplain Transition Transitions} linking StartEvents, Tasks and EndEvents. + * </ul> + * + * @author tknall + * + */ +public class ProcessDefinition { + + private String id; + private StartEvent startEvent; + private Map<String, TaskInfo> taskInfos = new LinkedHashMap<>(); + private Map<String, EndEvent> endEvents = new LinkedHashMap<>(); + + /** + * Returns the unique identifier of the process definition. + * + * @return The unique identifier (never {@code null} if process definition comes from + * {@link ProcessDefinitionParser}). + */ + public String getId() { + return id; + } + + /** + * Sets the unique identifier of the process definition. + * + * @param id + * The unique identifier. + */ + public void setId(String id) { + this.id = id; + } + + /** + * Returns the start event of the process definition. + * + * @return The start event (never {@code null} if process definition comes from {@link ProcessDefinitionParser}). + */ + public StartEvent getStartEvent() { + return startEvent; + } + + /** + * Sets the start event of the process definition. + * + * @param startEvent + * The start event. + */ + public void setStartEvent(StartEvent startEvent) { + this.startEvent = startEvent; + } + + /** + * Returns a map containing the tasks of the process definition. + * + * @return The tasks (map is never {@code null} if process definition comes from {@link ProcessDefinitionParser}). + */ + public Map<String, TaskInfo> getTaskInfos() { + return taskInfos; + } + + /** + * Sets the map containing the tasks. + * + * @param taskInfos + * The map containing the tasks. + */ + public void setTaskInfos(Map<String, TaskInfo> taskInfos) { + this.taskInfos = taskInfos; + } + + /** + * Returns a map containing the end events of the process description. + * + * @return The map containing the end events (map is never {@code null} if process definition comes from + * {@link ProcessDefinitionParser}). + */ + public Map<String, EndEvent> getEndEvents() { + return endEvents; + } + + /** + * Sets a map containing the end events of the process description. + * + * @param endEvents + * The map containing the end events. + */ + public void setEndEvents(Map<String, EndEvent> endEvents) { + this.endEvents = endEvents; + } + + /** + * Returns the process node associated with the given {@code id}. + * + * @param id + * The identifier of the process node. + * @return The process node (may be {code null} when no process node with the given {@code id} exists). + */ + public ProcessNode getProcessNode(String id) { + Objects.requireNonNull(id, "Identifier must not be null."); + if (startEvent != null && id.equals(startEvent.getId())) { + return startEvent; + } + TaskInfo task = taskInfos.get(id); + if (task != null) { + return task; + } + return endEvents.get(id); + } + + @Override + public String toString() { + StringBuilder builder = new StringBuilder(); + if (id != null) { + builder.append("id="); + builder.append(id); + } + if (startEvent != null) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("startEvent="); + builder.append(startEvent); + } + if (taskInfos != null && !taskInfos.isEmpty()) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("tasksInfos="); + builder.append(taskInfos.values()); + } + if (endEvents != null && !endEvents.isEmpty()) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("endEvents="); + builder.append(endEvents.values()); + } + builder.insert(0, "ProcessDefinition ["); + builder.append("]"); + return builder.toString(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/ProcessNode.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/ProcessNode.java new file mode 100644 index 00000000..e1109336 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/ProcessNode.java @@ -0,0 +1,71 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.model; + +import java.util.ArrayList; +import java.util.List; + +import at.gv.egiz.eaaf.core.impl.idp.process.ProcessDefinitionParser; + +/** + * Represents a {@link StartEvent}, an {@link EndEvent} or a {@linkplain TaskInfo Task}. + * @author tknall + * + */ +public abstract class ProcessNode { + + private String id; + private List<Transition> outgoingTransitions = new ArrayList<>(); + private List<Transition> incomingTransitions = new ArrayList<>(); + + /** + * Returns the unique identifier of the process node. + * + * @return The unique identifier (never {@code null} if process node comes from a process definition from + * {@link ProcessDefinitionParser}). + */ + public String getId() { + return id; + } + + /** + * Sets the unique identifier of the process node. + * @param id The unique identifier. + */ + public void setId(String id) { + this.id = id; + } + + /** + * Returns a list of transitions pointing from this process node to another one. + * @return A list of transitions (never {@code null} if process node comes from a process definition from {@link ProcessDefinitionParser}). + */ + public List<Transition> getOutgoingTransitions() { + return outgoingTransitions; + } + + /** + * Sets the list of transitions pointing from this process node to another one. + * @param outgoingTransitions The list of transitions originating from this process node. + */ + public void setOutgoingTransitions(List<Transition> outgoingTransitions) { + this.outgoingTransitions = outgoingTransitions; + } + + /** + * Returns a list of transitions pointing from another process node to this one. + * @return A list of transitions (never {@code null} if process node comes from a process definition from {@link ProcessDefinitionParser}). + */ + public List<Transition> getIncomingTransitions() { + return incomingTransitions; + } + + /** + * Sets the list of transitions pointing from another process node to this one. + * @param incomingTransitions A list of transitions pointing to this process node. + */ + public void setIncomingTransitions(List<Transition> incomingTransitions) { + this.incomingTransitions = incomingTransitions; + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/StartEvent.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/StartEvent.java new file mode 100644 index 00000000..3d3111c2 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/StartEvent.java @@ -0,0 +1,47 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.model; + +import java.io.Serializable; + +import org.apache.commons.collections4.CollectionUtils; + +/** + * Represents a start event. Each process description contains a single start event. Process execution starts with a + * start event. + * + * @author tknall + * + */ +public class StartEvent extends ProcessNode implements Serializable { + + private static final long serialVersionUID = 1L; + + @Override + public String toString() { + StringBuilder builder = new StringBuilder(); + builder.append("StartEvent ["); + if (getId() != null) { + builder.append("id="); + builder.append(getId()); + } + if (CollectionUtils.isNotEmpty(getIncomingTransitions())) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("incomingTransitions="); + builder.append(getIncomingTransitions()); + } + if (CollectionUtils.isNotEmpty(getOutgoingTransitions())) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("outgoingTransitions="); + + builder.append(getOutgoingTransitions()); + } + builder.append("]"); + return builder.toString(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/TaskInfo.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/TaskInfo.java new file mode 100644 index 00000000..b7171236 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/TaskInfo.java @@ -0,0 +1,96 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.model; + +import java.io.Serializable; + +import org.apache.commons.collections4.CollectionUtils; + +import at.gv.egiz.eaaf.core.api.idp.process.Task; + +/** + * Represents information about a single task to be performed upon process execution. + * @author tknall + * + */ +public class TaskInfo extends ProcessNode implements Serializable { + + private static final long serialVersionUID = 1L; + private static final boolean DEFAULT_ASYNC = false; + + private String taskImplementingClass; + private boolean async = DEFAULT_ASYNC; + + /** + * Determines if the task is marked asynchronous ({@code true}) or synchronous ({@code false}). + * @return A flag indicating if the task should be executed asynchronously or synchronously. (Default: {@code false}) + */ + public boolean isAsync() { + return async; + } + + /** + * Marks a task to executed asynchronously ({@code true}) or synchronously ({@code false}). + * @param async The flag. + */ + public void setAsync(boolean async) { + this.async = async; + } + + /** + * Returns the class that implements the actual task (must implement {@link Task}). + * @return The task implementing class. + */ + public String getTaskImplementingClass() { + return taskImplementingClass; + } + + /** + * Sets the class that implements the actual task (must implement {@link Task}). + * @param taskImplementingClass The task implementing class. + */ + public void setTaskImplementingClass(String taskImplementingClass) { + this.taskImplementingClass = taskImplementingClass; + } + + @Override + public String toString() { + StringBuilder builder = new StringBuilder(); + if (getId() != null) { + builder.append("id="); + builder.append(getId()); + } + if (async != DEFAULT_ASYNC) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("async="); + builder.append(async); + } + if (taskImplementingClass != null) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("taskImplementingClass="); + builder.append(taskImplementingClass); + } + if (CollectionUtils.isNotEmpty(getIncomingTransitions())) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("incomingTransitions="); + builder.append(getIncomingTransitions()); + } + if (CollectionUtils.isNotEmpty(getOutgoingTransitions())) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("outgoingTransitions="); + builder.append(getOutgoingTransitions()); + } + builder.insert(0, "TaskInfo ["); + builder.append("]"); + return builder.toString(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/Transition.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/Transition.java new file mode 100644 index 00000000..7ac26c20 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/model/Transition.java @@ -0,0 +1,138 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.model; + +import java.io.Serializable; + +import at.gv.egiz.eaaf.core.impl.idp.process.ProcessDefinitionParser; + +/** + * Represents a single transition from a {@link StartEvent} or {@linkplain TaskInfo Task} to another + * {@linkplain TaskInfo Task} or {@link EndEvent}. + * + * @author tknall + * + */ +public class Transition implements Serializable { + + private static final long serialVersionUID = 1L; + + private String id; + private String conditionExpression; + private ProcessNode from; + private ProcessNode to; + + /** + * Returns the process node (effectively a {@link StartEvent} or {@linkplain TaskInfo Task}) the transition is + * pointing from. + * + * @return The transition's source process node (never {@code null} if transition comes from a process definition + * from {@link ProcessDefinitionParser}). + */ + public ProcessNode getFrom() { + return from; + } + + /** + * Sets the process node the transition is pointing from. + * + * @param from + * The transition's source process node. + */ + public void setFrom(ProcessNode from) { + this.from = from; + } + + /** + * Returns the process node (effectively a {@linkplain TaskInfo Task} or {@link EndEvent}) the transition is + * pointing to. + * + * @return The transition's destination process node (never {@code null} if transition comes from a process + * definition from {@link ProcessDefinitionParser}). + */ + public ProcessNode getTo() { + return to; + } + + /** + * Sets the process node the transition is pointing to. + * + * @param to + * The transition's destination process node. + */ + public void setTo(ProcessNode to) { + this.to = to; + } + + /** + * Returns the unique identifier of the transition. + * + * @return The unique identifier (may be {@code null}). + */ + public String getId() { + return id; + } + + /** + * Sets the unique identifier of the transition. + * + * @param id + * The unique identifier. + */ + public void setId(String id) { + this.id = id; + } + + /** + * Returns the condition expression for this transition. + * + * @return The condition expression (may be {@code null}). + */ + public String getConditionExpression() { + return conditionExpression; + } + + /** + * Sets the condition expression for this transition. + * + * @param conditionExpression + * The condition expression. + */ + public void setConditionExpression(String conditionExpression) { + this.conditionExpression = conditionExpression; + } + + @Override + public String toString() { + StringBuilder builder = new StringBuilder(); + if (id != null) { + builder.append("id="); + builder.append(id); + } + if (from != null) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("from.id="); + builder.append(from.getId()); + } + if (to != null) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("to.id="); + builder.append(to.getId()); + } + if (conditionExpression != null) { + if (builder.length() > 0) { + builder.append(", "); + } + builder.append("conditionExpression="); + builder.append(conditionExpression); + } + builder.insert(0, "Transition ["); + builder.append("]"); + return builder.toString(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/spring/SpringExpressionEvaluator.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/spring/SpringExpressionEvaluator.java new file mode 100644 index 00000000..d301b77e --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/spring/SpringExpressionEvaluator.java @@ -0,0 +1,63 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.spring; + +import java.util.Objects; + +import javax.annotation.PostConstruct; + +import org.apache.commons.lang3.BooleanUtils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.springframework.beans.factory.annotation.Autowired; +import org.springframework.context.ApplicationContext; +import org.springframework.context.expression.BeanFactoryResolver; +import org.springframework.expression.Expression; +import org.springframework.expression.ExpressionParser; +import org.springframework.expression.spel.standard.SpelExpressionParser; +import org.springframework.expression.spel.support.StandardEvaluationContext; + +import at.gv.egiz.eaaf.core.api.idp.process.ExpressionEvaluationContext; +import at.gv.egiz.eaaf.core.api.idp.process.ExpressionEvaluator; +import at.gv.egiz.eaaf.core.impl.idp.process.model.Transition; + +/** + * Expression evaluator for processing {@link Transition} conditions allowing to reference Spring beans from the + * application context. + * + * @author tknall + * + */ +public class SpringExpressionEvaluator implements ExpressionEvaluator { + + private Logger log = LoggerFactory.getLogger(getClass()); + private ExpressionParser parser = new SpelExpressionParser(); + private StandardEvaluationContext evaluationContext = new StandardEvaluationContext(); + + @Autowired(required = false) + private ApplicationContext ctx; + + @PostConstruct + private void init() { + if (ctx != null) { + evaluationContext.setBeanResolver(new BeanFactoryResolver(ctx)); + } + } + + @Override + public boolean evaluate(ExpressionEvaluationContext expressionContext, String expression) { + Objects.requireNonNull(expression, "Expression must not be null."); + log.trace("Evaluating '{}'.", expression); + + Expression expr = parser.parseExpression(expression); + Boolean result = expr.getValue(evaluationContext, expressionContext, Boolean.class); + if (result == null) { + log.warn("Evaluation of '{}' results in null-value.", expression); + } else { + log.debug("Expression '{}' -> {}", expression, result); + } + + return BooleanUtils.isTrue(result); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/AbstractAuthSourceServlet.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/AbstractAuthSourceServlet.java new file mode 100644 index 00000000..095c3439 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/AbstractAuthSourceServlet.java @@ -0,0 +1,118 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.springweb; + +import javax.servlet.http.HttpServlet; +import javax.servlet.http.HttpServletRequest; + +import org.apache.commons.lang3.StringUtils; +import org.springframework.beans.BeansException; +import org.springframework.beans.factory.NoSuchBeanDefinitionException; +import org.springframework.beans.factory.NoUniqueBeanDefinitionException; +import org.springframework.web.context.WebApplicationContext; +import org.springframework.web.context.support.WebApplicationContextUtils; + +import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext; +import at.gv.egiz.eaaf.core.api.idp.process.ProcessEngine; +import at.gv.egiz.eaaf.core.impl.idp.process.ProcessInstance; + +/** + * Abstract HttpServlet that provides means for retrieving the process engine (Spring Web required) as well as + * retrieving the underlying process instance and execution context evaluating a certain request parameter. + * + * @author tknall + * + */ +public abstract class AbstractAuthSourceServlet extends HttpServlet { + + private static final long serialVersionUID = 1L; + + private ProcessEngine processEngine; + + /** + * Returns the name of the request parameter representing the respective instance id. + * <p/>Default is {@code processInstanceId}. + * @return The request parameter name. + */ + public String getProcessInstanceIdParameterName() { + return "processInstanceId"; + } + + /** + * Returns the underlying process engine instance. + * + * @return The process engine (never {@code null}). + * @throws NoSuchBeanDefinitionException + * if no {@link ProcessEngine} bean was found. + * @throws NoUniqueBeanDefinitionException + * if more than one {@link ProcessEngine} bean was found. + * @throws BeansException + * if a problem getting the {@link ProcessEngine} bean occurred. + * @throws IllegalStateException + * if the Spring WebApplicationContext was not found, which means that the servlet is used outside a + * Spring web environment. + */ + public synchronized ProcessEngine getProcessEngine() { + if (processEngine == null) { + WebApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(getServletContext()); + if (ctx == null) { + throw new IllegalStateException( + "Unable to find Spring WebApplicationContext. Servlet needs to be executed within a Spring web environment."); + } + processEngine = ctx.getBean(ProcessEngine.class); + } + return processEngine; + } + + /** + * Retrieves the process instance referenced by the request parameter {@link #getProcessInstanceIdParameterName()}. + * + * @param request + * The HttpServletRequest. + * @return The process instance (never {@code null}). + * @throws NoSuchBeanDefinitionException + * if no {@link ProcessEngine} bean was found. + * @throws NoUniqueBeanDefinitionException + * if more than one {@link ProcessEngine} bean was found. + * @throws BeansException + * if a problem getting the {@link ProcessEngine} bean occurred. + * @throws IllegalStateException + * if the Spring WebApplicationContext was not found, which means that the servlet is used outside a + * Spring web environment. + * @throws IllegalArgumentException + * in case the process instance id referenced by the request parameter + * {@link #getProcessInstanceIdParameterName()} does not exist. + */ + public ProcessInstance getProcessInstance(HttpServletRequest request) { + String processInstanceId = StringUtils.trimToNull(request.getParameter(getProcessInstanceIdParameterName())); + if (processInstanceId == null) { + throw new IllegalArgumentException("Missing request parameter '" + getProcessInstanceIdParameterName() + "'."); + } + return getProcessEngine().getProcessInstance(processInstanceId); + } + + /** + * Retrieves the execution context for the respective process instance referenced by the request parameter + * {@link #getProcessInstanceIdParameterName()}. + * + * @param request + * The HttpServletRequest. + * @return The execution context (never {@code null}). + * @throws NoSuchBeanDefinitionException + * if no {@link ProcessEngine} bean was found. + * @throws NoUniqueBeanDefinitionException + * if more than one {@link ProcessEngine} bean was found. + * @throws BeansException + * if a problem getting the {@link ProcessEngine} bean occurred. + * @throws IllegalStateException + * if the Spring WebApplicationContext was not found, which means that the servlet is used outside a + * Spring web environment. + * @throws IllegalArgumentException + * in case the process instance id referenced by the request parameter + * {@link #getProcessInstanceIdParameterName()} does not exist. + */ + public ExecutionContext getExecutionContext(HttpServletRequest request) { + return getProcessInstance(request).getExecutionContext(); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/AbstractTask.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/AbstractTask.java new file mode 100644 index 00000000..446bf690 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/AbstractTask.java @@ -0,0 +1,101 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.springweb; + +import javax.servlet.http.HttpServletRequest; +import javax.servlet.http.HttpServletResponse; + +import org.springframework.web.context.request.RequestAttributes; +import org.springframework.web.context.request.RequestContextHolder; +import org.springframework.web.context.request.ServletRequestAttributes; +import org.springframework.web.filter.RequestContextFilter; + +import at.gv.egiz.eaaf.core.api.IRequest; +import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext; +import at.gv.egiz.eaaf.core.api.idp.process.Task; +import at.gv.egiz.eaaf.core.exceptions.TaskExecutionException; + +/** + * Abstract task implementation providing {@link HttpServletRequest} and {@link HttpServletResponse}. + * <p/> + * Note that this abstract task requires the Spring (web) framework including a {@link RequestContextFilter} to be set + * within {@code web.xml}. + * + * <pre> + * ... + * <filter> + * <filter-name>requestContextFilter</filter-name> + * <filter-class>org.springframework.web.filter.RequestContextFilter</filter-class> + * </filter> + * <filter-mapping> + * <filter-name>requestContextFilter</filter-name> + * <url-pattern>/*</url-pattern> + * </filter-mapping> + * ... + * </pre> + * + * @author tknall + * @author tlenz + * + */ +public abstract class AbstractTask implements Task { + + /** + * Executes the task providing the underlying {@link ExecutionContext} {@code executionContext} as well as the + * respective {@link HttpServletRequest} and {@link HttpServletResponse}. + * + * @param executionContext + * The execution context (never {@code null}). + * @param request + * The HttpServletRequest (never {@code null}). + * @param response + * The HttpServletResponse (never {@code null}). + * @throws IllegalStateException + * Thrown in case the task is nur being run within the required environment. Refer to javadoc for + * further information. + * @throws Exception + * Thrown in case of error executing the task. + */ + public abstract void execute(ExecutionContext executionContext, HttpServletRequest request, + HttpServletResponse response) throws TaskExecutionException; + + /** + * Executes the task providing the underlying {@link ExecutionContext} {@code executionContext} + * and the {@link IRequest} {@code pendingReq }as well as the + * respective {@link HttpServletRequest} and {@link HttpServletResponse}. + * + * This method sets the pending-request object of the task implementation and starts the + * {@code execute} method of the task + * + * @param pendingReq The pending-request object (never {@code null}). + * @param executionContext The execution context (never {@code null}). + * @param request The HttpServletRequest (never {@code null}). + * @param response The HttpServletResponse (never {@code null}). + * @return The pending-request object, because Process-management works recursive + * + * @throws IllegalStateException + * Thrown in case the task is being run within the required environment. Refer to javadoc for + * further information. + * @throws Exception + * Thrown in case of error executing the task. + */ + protected abstract IRequest internalExecute(IRequest pendingReq, ExecutionContext executionContext, HttpServletRequest request, + HttpServletResponse response) throws TaskExecutionException; + + @Override + public IRequest execute(IRequest pendingReq, ExecutionContext executionContext) throws TaskExecutionException { + RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes(); + if (requestAttributes != null && requestAttributes instanceof ServletRequestAttributes) { + HttpServletRequest request = ((ServletRequestAttributes) requestAttributes).getRequest(); + HttpServletResponse response = ((ServletRequestAttributes) requestAttributes).getResponse(); + if (request == null || response == null) { + throw new IllegalStateException( + "Spring's RequestContextHolder did not provide HttpServletResponse. Did you forget to set the required org.springframework.web.filter.RequestContextFilter in your web.xml."); + } + return internalExecute(pendingReq, executionContext, request, response); + } else { + throw new IllegalStateException("Task needs to be executed within a Spring web environment."); + } + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/SpringWebExpressionEvaluator.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/SpringWebExpressionEvaluator.java new file mode 100644 index 00000000..229735e3 --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/springweb/SpringWebExpressionEvaluator.java @@ -0,0 +1,145 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.springweb; + +import java.io.Serializable; +import java.util.Collections; +import java.util.HashMap; +import java.util.Iterator; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Objects; + +import javax.annotation.PostConstruct; +import javax.servlet.http.HttpServletRequest; + +import org.apache.commons.lang3.ArrayUtils; +import org.apache.commons.lang3.BooleanUtils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.springframework.beans.factory.annotation.Autowired; +import org.springframework.context.ApplicationContext; +import org.springframework.context.expression.BeanFactoryResolver; +import org.springframework.expression.Expression; +import org.springframework.expression.ExpressionParser; +import org.springframework.expression.spel.standard.SpelExpressionParser; +import org.springframework.expression.spel.support.StandardEvaluationContext; + +import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext; +import at.gv.egiz.eaaf.core.api.idp.process.ExpressionEvaluationContext; +import at.gv.egiz.eaaf.core.api.idp.process.ExpressionEvaluator; +import at.gv.egiz.eaaf.core.impl.idp.process.model.Transition; + +/** + * Expression evaluator for processing {@link Transition} conditions allowing to + * <ul> + * <li>reference Spring beans from the application context using {@code @myBeanName...},</li> + * <li>{@link ExecutionContext} properties using {@code ctx['property']},</li> + * <li>Multi valued {@link HttpServletRequest} parameters using {@code requestParameters['foo']} (keep in mind that this + * expression returns an array of String values) and</li> + * <li>Single valued {@link HttpServletRequest} parameters using {@code requestParameter['foo']}</li> + * </ul> + * + * @author tknall + * + */ +public class SpringWebExpressionEvaluator implements ExpressionEvaluator { + + private Logger log = LoggerFactory.getLogger(getClass()); + private ExpressionParser parser = new SpelExpressionParser(); + private StandardEvaluationContext evaluationContext = new StandardEvaluationContext(); + + @Autowired(required = false) + private ApplicationContext ctx; + + @Autowired(required = false) + private HttpServletRequest request; + + @PostConstruct + private void init() { + if (ctx != null) { + evaluationContext.setBeanResolver(new BeanFactoryResolver(ctx)); + } + } + + /** + * Evaluation context that provides access to {@link HttpServletRequest} parameters using + * {@code requestParameter['foo']} for single value parameters or {@code requestParameters['foo']} for multi value + * parameters. Basic calls to {@code ctx} will be delegated. + * + * @author tknall + * + */ + private class SpringWebExpressionEvaluationContext implements ExpressionEvaluationContext { + + private static final long serialVersionUID = 1L; + + /** + * Creates a new expression evaluation context, providing access to HttpServletRequest parameter(s). + * + * @param delegate + * The original {@link ExpressionEvaluationContext} to be delegated to for {@code ctx['foo']} + * expressions. + */ + public SpringWebExpressionEvaluationContext(ExpressionEvaluationContext delegate) { + this.delegate = delegate; + } + + private ExpressionEvaluationContext delegate; + + @Override + public Map<String, Serializable> getCtx() { + return delegate.getCtx(); + } + + @SuppressWarnings("unused") + public Map<String, String> getRequestParameter() { + if (request != null) { + Map<String, String> singleValueMap = new HashMap<String, String>(); + Iterator<Entry<String, String[]>> it = request.getParameterMap().entrySet().iterator(); + while (it.hasNext()) { + Entry<String, String[]> entry = it.next(); + if (ArrayUtils.isNotEmpty(entry.getValue())) { + singleValueMap.put(entry.getKey(), entry.getValue()[0]); + } + } + return singleValueMap; + } else { + return Collections.<String, String> emptyMap(); + } + } + + @SuppressWarnings("unused") + public Map<String, String[]> getRequestParameters() { + if (request != null) { + return request.getParameterMap(); + } else { + return Collections.<String, String[]> emptyMap(); + } + } + + } + + @Override + public boolean evaluate(ExpressionEvaluationContext expressionContext, String expression) { + Objects.requireNonNull(expression, "Expression must not be null."); + log.trace("Evaluating '{}'.", expression); + + Expression expr = parser.parseExpression(expression); + Boolean result = null; + try { + result = expr.getValue(evaluationContext, new SpringWebExpressionEvaluationContext(expressionContext), + Boolean.class); + if (result == null) { + log.warn("Evaluation of '{}' results in null-value.", expression); + } else { + log.debug("Expression '{}' -> {}", expression, result); + } + } catch (Exception e) { + log.warn("Expression '{}' could not be processed.", expression, e); + } + + return BooleanUtils.isTrue(result); + } + +} diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/support/SecureRandomHolder.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/support/SecureRandomHolder.java new file mode 100644 index 00000000..0f581dae --- /dev/null +++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/process/support/SecureRandomHolder.java @@ -0,0 +1,37 @@ +/******************************************************************************* + *******************************************************************************/ +package at.gv.egiz.eaaf.core.impl.idp.process.support; + +import java.security.NoSuchAlgorithmException; +import java.security.SecureRandom; + +/** + * Holder for a secure random instance following the initialization on demand holder design pattern. The secure random + * instance is a singleton that is initialized on first usage. + * + * @author tknall + * + */ +public class SecureRandomHolder { + + private SecureRandomHolder() { + } + + private static final SecureRandom SRND_INSTANCE; + static { + try { + SRND_INSTANCE = SecureRandom.getInstance("SHA1PRNG"); + } catch (NoSuchAlgorithmException e) { + throw new RuntimeException("Unable to instantiate SHA1PRNG.", e); + } + } + + /** + * Returns a secure random generator instance. + * @return The secure random instance. + */ + public static SecureRandom getInstance() { + return SecureRandomHolder.SRND_INSTANCE; + } + +}
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