persistence

We are developing a WCF based system. In the process we are trying to lock some data from being modified by more than one users. So we decided to have a data structure that will contain the necessary information for the locking logic to execute (by for example storing the ID of the locked objects) The problem we are having is persisting that data between sessions. Is there anyway we can avoid executing expensive database calls? I am not sure how can we do that in WCF since it can only persist data (in memory) during an open session. Static members of the service implementing class are shared

I have Issue with using database I was going with this tutorial http://vimeo.com/58969923# (one from playframework.com page) in the model: play-2.2.1/jcirs/app/models/MedicalIncident.java public class MedicalIncident extends Model{} I am trying to use Entity. For that I have to import: javax.persistence.* and play.db.ebean.* but none of them can be found. The error is package javax.persistence does not exist What should I do? Use any other database engine? Or should download some dependency. I would like to go with playframework best way. Please help. My configuration application.conf: db

I use JDO within GAE to batch persist objects using the following method: public void makePersistent(PersistenceManager pm, List<Regeling> makePersistent) { Transaction tx = pm.currentTransaction(); try { // Start the transaction tx.begin(); // Persist to the datastore // pm.makePersistentAll(makePersistent); for (int i = 0; i < makePersistent.size(); i += BATCH_SIZE) { int last = i + BATCH_SIZE; last = last > makePersistent.size() ? makePersistent.size() : last; pm.makePersistentAll(makePersistent.subList(i, last)); pm.flush(); System.out.println("Made "+last+" items persistent."); } //

I want to do this column can´t be null but when I insert in database one register values null this allows me inserted. I read documentation and I don´t know why doesn´t work. @Column(name="QWECOD", nullable = false) private String qwe; THX UPDATE: I´m using Toplink and java org.eclipse.persistence.eclipselink:2.4.2 . Andreas Aumayr I think nullable is used if you generate the schema, using the implementation of the entitymanager. I don't know whether it is / has to be validated while persisting an entity as well. Maybe it helps if you use the @NotNull annotation, but this is NOT plain JPA. It