diff --git a/src/main/java/org/gcube/vremanagement/executor/persistence/orientdb/OrientDBPersistenceConnector.java b/src/main/java/org/gcube/vremanagement/executor/persistence/orientdb/OrientDBPersistenceConnector.java
index 1e83419..1205320 100644
--- a/src/main/java/org/gcube/vremanagement/executor/persistence/orientdb/OrientDBPersistenceConnector.java
+++ b/src/main/java/org/gcube/vremanagement/executor/persistence/orientdb/OrientDBPersistenceConnector.java
@@ -20,7 +20,6 @@ import org.gcube.vremanagement.executor.persistence.SmartExecutorPersistenceConf
 import org.gcube.vremanagement.executor.persistence.SmartExecutorPersistenceConnector;
 import org.gcube.vremanagement.executor.plugin.PluginDeclaration;
 import org.gcube.vremanagement.executor.plugin.PluginStateEvolution;
-import org.gcube.vremanagement.executor.plugin.RunOn;
 import org.gcube.vremanagement.executor.scheduledtask.ScheduledTask;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -49,7 +48,7 @@ public class OrientDBPersistenceConnector extends
 	protected final String UUID = "uuid";
 	protected final String ITERATION = "iteration";
 	protected final String TIMESTAMP = "timestamp";
-
+	
 	protected final String RUN_ON = "runOn";
 
 	protected OPartitionedDatabasePool oPartitionedDatabasePool;
@@ -329,46 +328,11 @@ public class OrientDBPersistenceConnector extends
 			}
 		}
 	}
-
+	
 	@Override
 	public void reserveScheduledTask(ScheduledTask scheduledTask)
 			throws SchedulePersistenceException {
-		ODatabaseDocumentTx db = null;
-		try {
-			db = oPartitionedDatabasePool.acquire();
-			UUID uuid = scheduledTask.getUUID();
-
-			ODocument doc = getScheduledTaskDocument(db, uuid);
-
-			
-			Long timestamp = doc.field(TIMESTAMP);
-			if (timestamp!=null && timestamp.compareTo(scheduledTask.getTimestamp())!=0) {
-				throw new SchedulePersistenceException(
-						"The ScheduledTask has been already reserved.");
-			}
-
-			RunOn runOn = ScheduledTask.generateRunOn();
-			
-			ODocument runOnDocument = new ODocument();
-			runOnDocument.fromJSON(mapper.writeValueAsString(runOn));
-			doc.field(RUN_ON, runOnDocument);
-
-			timestamp = Calendar.getInstance().getTimeInMillis();
-			doc.field(TIMESTAMP, timestamp);
-
-			doc.save();
-			db.commit();
-
-		} catch (Exception e) {
-			if (db != null) {
-				db.rollback();
-			}
-			throw new SchedulePersistenceException(e);
-		} finally {
-			if (db != null) {
-				db.close();
-			}
-		}
+		releaseScheduledTask(scheduledTask);
 	}
 
 	@Override
@@ -396,31 +360,7 @@ public class OrientDBPersistenceConnector extends
 	@Override
 	public void removeScheduledTask(ScheduledTask scheduledTask)
 			throws SchedulePersistenceException {
-		ODatabaseDocumentTx db = null;
-		try {
-			db = oPartitionedDatabasePool.acquire();
-			UUID uuid = scheduledTask.getUUID();
-
-			ODocument doc = getScheduledTaskDocument(db, uuid);
-
-			Long timestamp = doc.field(TIMESTAMP);
-			if (timestamp!=null && timestamp.compareTo(scheduledTask.getTimestamp())!=0) {
-				throw new SchedulePersistenceException(
-						"The ScheduledTask has been changed.");
-			}
-
-			doc.delete();
-			db.commit();
-		} catch (Exception e) {
-			if (db != null) {
-				db.rollback();
-			}
-			throw new SchedulePersistenceException(e);
-		} finally {
-			if (db != null) {
-				db.close();
-			}
-		}
+		removeScheduledTask(scheduledTask.getUUID());
 	}
 
 	@Override
@@ -447,29 +387,6 @@ public class OrientDBPersistenceConnector extends
 	@Override
 	public void releaseScheduledTask(ScheduledTask scheduledTask)
 			throws SchedulePersistenceException {
-		ODatabaseDocumentTx db = null;
-		try {
-			db = oPartitionedDatabasePool.acquire();
-			UUID uuid = scheduledTask.getUUID();
-			ODocument doc = getScheduledTaskDocument(db, uuid);
-
-			Long timestamp = doc.field(TIMESTAMP);
-			if (timestamp!=null && timestamp.compareTo(scheduledTask.getTimestamp())!=0) {
-				throw new SchedulePersistenceException(
-						"The ScheduledTask has been changed.");
-			}
-
-			doc.removeField(RUN_ON);
-			doc.save();
-		} catch (Exception e) {
-			if (db != null) {
-				db.rollback();
-			}
-			throw new SchedulePersistenceException(e);
-		} finally {
-			if (db != null) {
-				db.close();
-			}
-		}
+		releaseScheduledTask(scheduledTask.getUUID());
 	}
 }
diff --git a/src/main/java/org/gcube/vremanagement/executor/scheduledtask/ScheduledTask.java b/src/main/java/org/gcube/vremanagement/executor/scheduledtask/ScheduledTask.java
index e78a45b..005b824 100644
--- a/src/main/java/org/gcube/vremanagement/executor/scheduledtask/ScheduledTask.java
+++ b/src/main/java/org/gcube/vremanagement/executor/scheduledtask/ScheduledTask.java
@@ -30,8 +30,6 @@ public class ScheduledTask {
 	
 	public static final String LAUNCH_PARAMETER = "launchParameter";
 	
-	protected Long timestamp;
-	
 	protected UUID uuid;
 	@JsonProperty(value=LAUNCH_PARAMETER)
 	protected LaunchParameter launchParameter;
@@ -57,13 +55,6 @@ public class ScheduledTask {
 		this.runOn = runOn;
 	}
 	
-	/**
-	 * @return the timestamp
-	 */
-	public Long getTimestamp() {
-		return timestamp;
-	}
-	
 	/**
 	 * @return the uuid
 	 */