[jboss-user] [JBoss Seam] - 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
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