integrate process engine from project 'dti-process-engine' - INCOMPLETE!

  - commit neccessary in order to avoid blocking the development process

additional small fix due to earlier package renaming

23 files changed, 1992 insertions, 0 deletions

diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ExecutionContextImpl.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ExecutionContextImpl.java
new file mode 100644
index 000000000..87ee57a24
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ExecutionContextImpl.java
@@ -0,0 +1,79 @@
+package at.gv.egovernment.moa.id.process;
+
+import java.io.Serializable;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+import com.datentechnik.process_engine.api.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ExpressionEvaluationContextImpl.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ExpressionEvaluationContextImpl.java
new file mode 100644
index 000000000..acc10449f
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ExpressionEvaluationContextImpl.java
@@ -0,0 +1,44 @@
+package at.gv.egovernment.moa.id.process;
+
+import java.io.Serializable;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+import com.datentechnik.process_engine.api.ExecutionContext;
+import com.datentechnik.process_engine.api.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessDefinitionParser.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessDefinitionParser.java
new file mode 100644
index 000000000..b38bb7aa0
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessDefinitionParser.java
@@ -0,0 +1,224 @@
+package at.gv.egovernment.moa.id.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 com.datentechnik.process_engine.model.EndEvent;
+import com.datentechnik.process_engine.model.ProcessDefinition;
+import com.datentechnik.process_engine.model.ProcessNode;
+import com.datentechnik.process_engine.model.StartEvent;
+import com.datentechnik.process_engine.model.TaskInfo;
+import com.datentechnik.process_engine.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://www.datentechnik.com/process-engine/processdefinition/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("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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessDefinitionParserException.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessDefinitionParserException.java
new file mode 100644
index 000000000..0c214750d
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessDefinitionParserException.java
@@ -0,0 +1,35 @@
+package at.gv.egovernment.moa.id.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessEngine.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessEngine.java
new file mode 100644
index 000000000..b4135ee41
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessEngine.java
@@ -0,0 +1,113 @@
+package at.gv.egovernment.moa.id.process;
+
+
+import java.io.InputStream;
+import java.io.Serializable;
+
+import com.datentechnik.process_engine.api.ExecutionContext;
+import com.datentechnik.process_engine.model.ProcessDefinition;
+
+/**
+ * Process engine providing means for starting and resuming processes.
+ * 
+ * @author tknall
+ */
+public interface ProcessEngine {
+
+	/**
+	 * Registers a new process definition. Note that existing definitions with the same identifier will be replaced.
+	 * 
+	 * @param processDefinition
+	 *            The process definition to be registered.
+	 */
+	void registerProcessDefinition(ProcessDefinition processDefinition);
+
+	/**
+	 * Registers a new process definition given as {@link InputStream}. Note that existing definitions with the same identifier will be replaced.
+	 *
+	 * @param processDefinitionInputStream The input stream to the definition to be registered.
+	 * @throws ProcessDefinitionParserException Thrown in case of an error parsing the process definition.
+	 */
+	void registerProcessDefinition(InputStream processDefinitionInputStream) throws ProcessDefinitionParserException;
+
+	/**
+	 * Creates a process instance according to the referenced process definition.
+	 * <p/>
+	 * Note that the method returns a process instance which will be needed in order to start a process or to continue
+	 * process execution after asynchronous task execution (refer to {@link #start(ProcessInstance)} and
+	 * {@link #signal(ProcessInstance)} for further information).
+	 * 
+	 * @param processDefinitionId
+	 *            The identifier of the respective process definition.
+	 * @param executionContext The execution context (may be {@code null}).
+	 * @return The newly created process instance (never {@code null}).
+	 * @throws ProcessExecutionException
+	 *             Thrown in case of error, e.g. when a {@code processDefinitionId} is referenced that does not exist.
+	 */
+	ProcessInstance createProcessInstance(String processDefinitionId, ExecutionContext executionContext) throws ProcessExecutionException;
+
+	/**
+	 * Creates a process instance according to the referenced process definition.
+	 * <p/>
+	 * Note that the method returns a process instance which will be needed in order to start a process or to continue
+	 * process execution after asynchronous task execution (refer to {@link #start(ProcessInstance)} and
+	 * {@link #signal(ProcessInstance)} for further information).
+	 * 
+	 * @param processDefinitionId
+	 *            The identifier of the respective process definition.
+	 * @return The newly created process instance (never {@code null}).
+	 * @throws ProcessExecutionException
+	 *             Thrown in case of error, e.g. when a {@code processDefinitionId} is referenced that does not exist.
+	 */
+	ProcessInstance createProcessInstance(String processDefinitionId) throws ProcessExecutionException;
+
+	/**
+	 * Returns the process instance with a given {@code processInstanceId}.
+	 * 
+	 * @param processInstanceId
+	 *            The process instance id.
+	 * @return The process instance (never {@code null}).
+	 * @throws IllegalArgumentException
+	 *             In case the process instance does not/no longer exist.
+	 */
+	ProcessInstance getProcessInstance(String processInstanceId);
+
+	/**
+	 * Starts the process using the given {@code processInstance}.
+	 * 
+	 * @param processInstance
+	 *            The process instance.
+	 * @throws ProcessExecutionException
+	 *             Thrown in case of error.
+	 */
+	void start(ProcessInstance processInstance) throws ProcessExecutionException;
+
+	/**
+	 * Resumes process execution after an asynchronous task has been executed.
+	 * 
+	 * @param processInstance
+	 *            The process instance.
+	 * @throws ProcessExecutionException
+	 *             Thrown in case of error.
+	 */
+	void signal(ProcessInstance processInstance) throws ProcessExecutionException;
+
+	/**
+	 * Performs cleanup, removing all process instances that have not been used for a certain time.
+	 * 
+	 * @see #setProcessInstanceMaxIdleTimeSeconds(long)
+	 */
+	void cleanup();
+
+	/**
+	 * Returns the first process instance with a process context containing some {@code value} stored under key {@code key}.
+	 * 
+	 * @param key
+	 *            The key.
+	 * @param value
+	 *            The value that needs to match.
+	 * @return The process instance or {@code null} in case no process instance was found.
+	 */
+	ProcessInstance findProcessInstanceWith(String key, Serializable value);
+
+}
\ No newline at end of file
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessEngineImpl.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessEngineImpl.java
new file mode 100644
index 000000000..8f9d73b3d
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessEngineImpl.java
@@ -0,0 +1,304 @@
+package at.gv.egovernment.moa.id.process;
+
+import java.io.InputStream;
+import java.io.Serializable;
+import java.util.Date;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Objects;
+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 com.datentechnik.process_engine.api.ExecutionContext;
+import com.datentechnik.process_engine.api.ExpressionEvaluationContext;
+import com.datentechnik.process_engine.api.ExpressionEvaluator;
+import com.datentechnik.process_engine.api.Task;
+import com.datentechnik.process_engine.model.EndEvent;
+import com.datentechnik.process_engine.model.ProcessDefinition;
+import com.datentechnik.process_engine.model.ProcessNode;
+import com.datentechnik.process_engine.model.StartEvent;
+import com.datentechnik.process_engine.model.TaskInfo;
+import com.datentechnik.process_engine.model.Transition;
+
+/**
+ * Process engine implementation allowing starting and continuing processes as well as providing means for cleanup actions.
+ * @author tknall
+ *
+ */
+public class ProcessEngineImpl implements ProcessEngine {
+	
+	private Logger log = LoggerFactory.getLogger(getClass());
+	
+	private ProcessDefinitionParser pdp = new ProcessDefinitionParser();
+
+	private Map<String, ProcessDefinition> processDefinitions = new ConcurrentHashMap<String, ProcessDefinition>();
+	private Map<String, ProcessInstance> processInstances = new ConcurrentHashMap<String, ProcessInstance>();
+	
+	private final static String MDC_CTX_PI_NAME = "processInstanceId";
+	private final static String MDC_CTX_TASK_NAME = "taskId";
+	
+	private static final long DEFAULT_PROCESS_INSTANCE_MAX_AGE_SECONDS = 3600;
+	private long processInstanceIdleTimeSeconds = DEFAULT_PROCESS_INSTANCE_MAX_AGE_SECONDS;
+	private ExpressionEvaluator transitionConditionExpressionEvaluator;
+	
+	@Override
+	public void registerProcessDefinition(ProcessDefinition processDefinition) {
+		log.info("Registering process definition '{}'.", processDefinition.getId());
+		processDefinitions.put(processDefinition.getId(), processDefinition);
+	}
+
+	@Override
+	public void registerProcessDefinition(InputStream processDefinitionInputStream) throws ProcessDefinitionParserException{
+		registerProcessDefinition(pdp.parse(processDefinitionInputStream));
+	}
+
+	/**
+	 * 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);
+		}
+	}
+	
+	/**
+	 * Defines the time frame in seconds an idle process instance will be managed by the process engine. A process
+	 * instance with an idle time larger than the given time will be removed.
+	 * <p/>
+	 * Note that {@link #cleanup()} needs to be called in order to remove expired process instances.
+	 * 
+	 * @param processInstanceMaxIdleTimeSeconds
+	 *            The maximum idle time in seconds.
+	 */
+	public void setProcessInstanceMaxIdleTimeSeconds(long processInstanceMaxIdleTimeSeconds) {
+		this.processInstanceIdleTimeSeconds = processInstanceMaxIdleTimeSeconds;
+	}
+
+	/**
+	 * 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 ProcessInstance 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());
+		processInstances.put(pi.getId(), pi);
+		return pi;
+	}
+
+	@Override
+	public ProcessInstance createProcessInstance(String processDefinitionId) throws ProcessExecutionException {
+		return createProcessInstance(processDefinitionId, null);
+	}
+
+	@Override
+	public void start(ProcessInstance pi) throws ProcessExecutionException {
+		MDC.put(MDC_CTX_PI_NAME, pi.getId());
+		try {
+			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);
+		} finally {
+			MDC.remove(MDC_CTX_PI_NAME);
+		}
+	}
+	
+	@Override
+	public void signal(ProcessInstance pi) throws ProcessExecutionException {
+		MDC.put(MDC_CTX_PI_NAME, pi.getId());
+		try {
+			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);
+			execute(pi);
+		} finally {
+			MDC.remove(MDC_CTX_PI_NAME);
+		}
+	}
+	
+	@Override
+	public synchronized void cleanup() {
+		log.trace("Cleanup job started.");
+		Iterator<Entry<String, ProcessInstance>> it = processInstances.entrySet().iterator();
+		while (it.hasNext()) {
+			Entry<String, ProcessInstance> entry = it.next();
+			ProcessInstance pi = entry.getValue();
+			log.trace("Checking process instance {}.", pi);
+			long ageMillis = new Date().getTime() - pi.getLru().getTime();
+			if (ageMillis > processInstanceIdleTimeSeconds * 1000) {
+				log.info("Removing process instance '{}'.", pi.getId());
+				processInstances.remove(entry.getKey());
+			}
+		}
+		log.trace("Cleanup job completed.");
+	}
+
+	/**
+	 * Instantates 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);
+			Class<?> instanceClass = null;
+			try {
+				instanceClass = Class.forName(clazz, true, Thread.currentThread().getContextClassLoader());
+			} catch (Exception e) {
+				throw new ProcessExecutionException("Unable to get class '" + clazz + "' associated with task '" + ti.getId() + "' .", e);
+			}
+			if (!Task.class.isAssignableFrom(instanceClass)) {
+				throw new ProcessExecutionException("Class '" + clazz + "' associated with task '" + ti.getId() + "' is not assignable to " + Task.class.getName() + ".");
+			}
+			try {
+				task = (Task) instanceClass.newInstance();
+			} 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.
+	 * @throws ProcessExecutionException Thrown in case of error.
+	 */
+	private void execute(final ProcessInstance pi) 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());
+						task.execute(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());
+			processInstances.remove(pi.getId());
+			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);
+		}
+	}
+
+	@Override
+	public ProcessInstance getProcessInstance(String processInstanceId) {
+		ProcessInstance processInstance = processInstances.get(processInstanceId);
+		if (processInstance == null) {
+			throw new IllegalArgumentException("The process instance '" + processInstanceId + "' does not/no longer exist.");
+		}
+		return processInstance;
+	}
+
+	@Override
+	public ProcessInstance findProcessInstanceWith(String key, Serializable value) {
+		Iterator<ProcessInstance> it = processInstances.values().iterator();
+		while (it.hasNext()) {
+			ProcessInstance pi = it.next();
+			if (Objects.equals(pi.getExecutionContext().get(key), value)) {
+				return pi;
+			}
+		}
+		return null;
+	}
+	
+}
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessExecutionException.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessExecutionException.java
new file mode 100644
index 000000000..821bbe6dc
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessExecutionException.java
@@ -0,0 +1,36 @@
+package at.gv.egovernment.moa.id.process;
+
+/**
+ * Indicates a problem when executing a process.
+ * 
+ * @author tknall
+ * 
+ */
+public class ProcessExecutionException extends Exception {
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * Creates a new process execution exception providing a {@code message} describing the reason and the respective
+	 * {@code cause}.
+	 * 
+	 * @param message
+	 *            The message.
+	 * @param cause
+	 *            The cause.
+	 */
+	public ProcessExecutionException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+	/**
+	 * Creates a new process execution exception providing a {@code message} describing the reason.
+	 * 
+	 * @param message
+	 *            The message.
+	 */
+	public ProcessExecutionException(String message) {
+		super(message);
+	}
+
+}
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessInstance.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessInstance.java
new file mode 100644
index 000000000..0899426ca
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessInstance.java
@@ -0,0 +1,166 @@
+package at.gv.egovernment.moa.id.process;
+
+import java.io.Serializable;
+import java.util.Date;
+
+import org.apache.commons.lang3.RandomStringUtils;
+import org.apache.commons.lang3.time.DurationFormatUtils;
+
+import com.datentechnik.process_engine.api.ExecutionContext;
+import com.datentechnik.process_engine.model.ProcessDefinition;
+import com.datentechnik.process_engine.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;
+
+	/**
+	 * Creates a new process instance, based on a given process definition.<p/>
+	 * An execution context will be created internally.
+	 * 
+	 * @param processDefinition
+	 *            The process definition.
+	 */
+	ProcessInstance(ProcessDefinition processDefinition) {
+		this(processDefinition, null);
+	}
+
+	/**
+	 * 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 automatically be set (and overwritten if already set).
+	 * 
+	 * @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();
+		String pdIdLocalPart = RandomStringUtils.random(RND_ID_LENGTH, 0, 0, true, true, null,
+				SecureRandomHolder.getInstance());
+		if (executionContext == null) {
+			executionContext = new ExecutionContextImpl();
+		}
+		executionContext.setProcessInstanceId(this.processDefinition.getId() + "-" + pdIdLocalPart);
+		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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessInstanceState.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessInstanceState.java
new file mode 100644
index 000000000..2765283a0
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/ProcessInstanceState.java
@@ -0,0 +1,30 @@
+package at.gv.egovernment.moa.id.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExecutionContext.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExecutionContext.java
new file mode 100644
index 000000000..4a9dfc336
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExecutionContext.java
@@ -0,0 +1,63 @@
+package at.gv.egovernment.moa.id.process.api;
+
+import java.io.Serializable;
+import java.util.Set;
+
+/**
+ * Encapsulates data needed for or provided by task execution.
+ * 
+ * @author tknall
+ * 
+ */
+public interface ExecutionContext extends Serializable {
+
+	/**
+	 * Returns the identifier of underlying process instance.
+	 * 
+	 * @return The identifier of the process instance.
+	 */
+	String getProcessInstanceId();
+
+	/**
+	 * Sets the identifier of underlying process instance.
+	 * 
+	 * @param processInstanceId
+	 *            The identifier of the process instance.
+	 */
+	void setProcessInstanceId(String processInstanceId);
+
+	/**
+	 * Stores a serializable object using {@code key}.
+	 * 
+	 * @param key
+	 *            The key under that the {@code object} should be stored.
+	 * @param object The object to be stored.
+	 */
+	void put(String key, Serializable object);
+
+	/**
+	 * Returns an serializable object stored within this process context using {@code key}.
+	 * 
+	 * @param key
+	 *            The key that has been used to store the serializable object (may be {@code null}).
+	 * @return The object or {@code null} in case the key does not relate to a stored object or the stored object itself
+	 *         was {@code null}.
+	 */
+	Serializable get(String key);
+	
+	/**
+	 * Removes the object stored using {@code key}.
+	 * @param key
+	 *            The key that has been used to store the serializable object (may be {@code null}).
+	 * @return The object that has been removed or {@code null} there was no object stored using {@code key}.
+	 */
+	Serializable remove(String key);
+
+	/**
+	 * Returns an unmodifiable set containing the stored keys.
+	 * 
+	 * @return The keyset (never {@code null}).
+	 */
+	Set<String> keySet();
+
+}
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExpressionEvaluationContext.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExpressionEvaluationContext.java
new file mode 100644
index 000000000..bb3b267cf
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExpressionEvaluationContext.java
@@ -0,0 +1,23 @@
+package at.gv.egovernment.moa.id.process.api;
+
+import java.io.Serializable;
+import java.util.Map;
+
+import com.datentechnik.process_engine.model.Transition;
+
+/**
+ * Context used for evaluation of condition expressions set for {@linkplain Transition Transitions}.
+ * 
+ * @author tknall
+ * 
+ */
+public interface ExpressionEvaluationContext extends Serializable {
+
+	/**
+	 * Returns the context data map used for expression evaluation.
+	 * 
+	 * @return An unmodifiable map (never {@code null}).
+	 */
+	Map<String, Serializable> getCtx();
+
+}
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExpressionEvaluator.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExpressionEvaluator.java
new file mode 100644
index 000000000..fe0743201
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/ExpressionEvaluator.java
@@ -0,0 +1,25 @@
+package at.gv.egovernment.moa.id.process.api;
+
+/**
+ * Evaluates a given {@code expression} returning a boolean value.
+ * 
+ * @author tknall
+ */
+public interface ExpressionEvaluator {
+
+	/**
+	 * Evaluates a given {@code expression} returning a boolean value.
+	 * 
+	 * @param expressionContext
+	 *            The context which can be used for evaluation of the expression.
+	 * @param expression
+	 *            The expression resulting in a boolean (must not be {@code null}).
+	 * @return A boolean value.
+	 * @throws IllegalArgumentException
+	 *             In case of an invalid {@code expression}.
+	 * @throws NullPointerException
+	 *             In case of a {@code null} expression.
+	 */
+	boolean evaluate(ExpressionEvaluationContext expressionContext, String expression);
+
+}
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/Task.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/Task.java
new file mode 100644
index 000000000..6401b1d5d
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/api/Task.java
@@ -0,0 +1,21 @@
+package at.gv.egovernment.moa.id.process.api;
+
+
+/**
+ * Represents a single task to be performed upon process execution.
+ * 
+ * @author tknall
+ * 
+ */
+public interface Task {
+
+	/**
+	 * Executes this task.
+	 * 
+	 * @param executionContext
+	 *            Provides execution related information.
+	 * @throws Exception An exception upon task execution.
+	 */
+	void execute(ExecutionContext executionContext) throws Exception;
+
+}
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/EndEvent.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/EndEvent.java
new file mode 100644
index 000000000..49fb082ea
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/EndEvent.java
@@ -0,0 +1,42 @@
+package at.gv.egovernment.moa.id.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/ProcessDefinition.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/ProcessDefinition.java
new file mode 100644
index 000000000..19e78b0e6
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/ProcessDefinition.java
@@ -0,0 +1,158 @@
+package at.gv.egovernment.moa.id.process.model;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Objects;
+
+import com.datentechnik.process_engine.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/ProcessNode.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/ProcessNode.java
new file mode 100644
index 000000000..a94d33943
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/ProcessNode.java
@@ -0,0 +1,69 @@
+package at.gv.egovernment.moa.id.process.model;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import com.datentechnik.process_engine.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/StartEvent.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/StartEvent.java
new file mode 100644
index 000000000..60175e09c
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/StartEvent.java
@@ -0,0 +1,45 @@
+package at.gv.egovernment.moa.id.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/TaskInfo.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/TaskInfo.java
new file mode 100644
index 000000000..b7f13a880
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/TaskInfo.java
@@ -0,0 +1,94 @@
+package at.gv.egovernment.moa.id.process.model;
+
+import java.io.Serializable;
+
+import org.apache.commons.collections4.CollectionUtils;
+
+import com.datentechnik.process_engine.api.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/Transition.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/Transition.java
new file mode 100644
index 000000000..9d9c44c8c
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/model/Transition.java
@@ -0,0 +1,136 @@
+package at.gv.egovernment.moa.id.process.model;
+
+import java.io.Serializable;
+
+import com.datentechnik.process_engine.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/spring/SpringExpressionEvaluator.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/spring/SpringExpressionEvaluator.java
new file mode 100644
index 000000000..1c91cf780
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/spring/SpringExpressionEvaluator.java
@@ -0,0 +1,61 @@
+package at.gv.egovernment.moa.id.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 com.datentechnik.process_engine.api.ExpressionEvaluationContext;
+import com.datentechnik.process_engine.api.ExpressionEvaluator;
+import com.datentechnik.process_engine.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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/springweb/AbstractAuthSourceServlet.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/springweb/AbstractAuthSourceServlet.java
new file mode 100644
index 000000000..4b5af854e
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/springweb/AbstractAuthSourceServlet.java
@@ -0,0 +1,116 @@
+package at.gv.egovernment.moa.id.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 com.datentechnik.process_engine.ProcessEngine;
+import com.datentechnik.process_engine.ProcessInstance;
+import com.datentechnik.process_engine.api.ExecutionContext;
+
+/**
+ * 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/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/springweb/AbstractSpringWebSupportedTask.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/springweb/AbstractSpringWebSupportedTask.java
new file mode 100644
index 000000000..1f7fb7690
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/springweb/AbstractSpringWebSupportedTask.java
@@ -0,0 +1,73 @@
+package at.gv.egovernment.moa.id.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 com.datentechnik.process_engine.api.ExecutionContext;
+import com.datentechnik.process_engine.api.Task;
+
+/**
+ * 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>
+ * ...
+ * &lt;filter&gt;
+ *   &lt;filter-name&gt;requestContextFilter&lt;/filter-name&gt;
+ *   &lt;filter-class&gt;org.springframework.web.filter.RequestContextFilter&lt;/filter-class&gt;
+ * &lt;/filter&gt;
+ * &lt;filter-mapping&gt;
+ *   &lt;filter-name&gt;requestContextFilter&lt;/filter-name&gt;
+ *   &lt;url-pattern&gt;/*&lt;/url-pattern&gt;
+ * &lt;/filter-mapping&gt;
+ * ...
+ * </pre>
+ * 
+ * @author tknall
+ * 
+ */
+public abstract class AbstractSpringWebSupportedTask 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 Exception;
+
+	@Override
+	public void execute(ExecutionContext executionContext) throws Exception {
+		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.");
+			}
+			execute(executionContext, request, response);
+		} else {
+			throw new IllegalStateException("Task needs to be executed within a Spring web environment.");
+		}
+	}
+
+}
diff --git a/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/support/SecureRandomHolder.java b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/support/SecureRandomHolder.java
new file mode 100644
index 000000000..72677739a
--- /dev/null
+++ b/id/server/idserverlib/src/main/java/at/gv/egovernment/moa/id/process/support/SecureRandomHolder.java
@@ -0,0 +1,35 @@
+package at.gv.egovernment.moa.id.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;
+	}
+
+}
\ No newline at end of file