PersistenceContext in distributed environment
Hi,
I want to split up my seam application into 2 different application, so that I can use one JBoss as a webserver and another one as the application-server with the underlyng database. Therefor I use the EntityManager only on the application-server, so that all the updates etc. on the database all go through the same method. Now I experience problems when using my entities and want to use object, that are lazy-loaded.
One example, I have a User-object with a UserLog:
@Name("user")
@Scope(ScopeType.SESSION)
public class User implements Serializable {
...
@OneToMany(cascade = CascadeType.ALL, mappedBy = "user", fetch=FetchType.LAZY)
private Set<UserLog> userLogCollection ;
...
public Set<UserLog> getUserLogCollection() {
return this.userLogCollection;
}
protected void setUserLogCollection(Set<UserLog> userLogCollection) {
this.userLogCollection = userLogCollection;
}
public void addUserLog(UserLog userLog) {
if (this.userLogCollection == null) {
this.userLogCollection = new HashSet();
}
this.userLogCollection.add(userLog);
}
When I Login I query the EnitityManager through my application-server and return the user-object.
When I try to add a new UserLog-Object using the methods of my entity object I get a LIE, probably because the user-object is detached:
16:45:59,978 ERROR [LazyInitializationException] failed to lazily initialize a collection of role: common.entity.User.userLogCollection, no session or session was closed org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: common.entity.User.userLogCollection, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:350) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:343) at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86) at org.hibernate.collection.PersistentSet.toString(PersistentSet.java:309) at java.lang.String.valueOf(String.java:2615) at java.lang.StringBuilder.append(StringBuilder.java:116)
When I do this through a method on my application-server together with a em.merge, everything works fine, because the entity becomes managed again. But this cannot be the solution, as would have to write a method for every lazy-loaded object on my application-server.
public User addUserLog(User user, UserLog userLog) {
User userTmp = (User) em.merge(user);
userTmp.addUserLog(userLog);
return userTmp;
}
I tryied to work with the Seam Managed Persistence Context, but as far as I could see in the documentation I have to initialize the EntityManager through the Seam-@In-Annotation, which doesn´t seem very good, if I would like to have seam-independent controller-beans on my application server.
What would be the best solution to work with lazily-loaded objects in a distributed environment? Does anyone have some experiences with that and therefor has a good recommendation?
Thank you very much
Thomas
