The book is great! Learned a lot...

But there is this small problem that prevents me from running the helloworld-jpa example..The following stack trace is thrown...

Can someone throw some light at this? Thanks in advance

[java] 15:58:36,812 WARN FileZippedJarVisitor:37 - Unable to find file (ig
nored): file:/G:/Hibernate%20CaveatEmptor%20Examples/jpwh-gettingstarted-070401/
helloworld-jpa/build
[java] java.io.FileNotFoundException: G:\Hibernate CaveatEmptor Examples\jp
wh-gettingstarted-070401\helloworld-jpa\build (Access is denied)
[java] at java.util.zip.ZipFile.open(Native Method)
[java] at java.util.zip.ZipFile.<init>(ZipFile.java:114)
[java] at java.util.jar.JarFile.<init>(JarFile.java:133)
[java] at java.util.jar.JarFile.<init>(JarFile.java:70)
[java] at org.hibernate.ejb.packaging.FileZippedJarVisitor.doProcessEle
ments(FileZippedJarVisitor.java:34)
[java] at org.hibernate.ejb.packaging.JarVisitor.getMatchingEntries(Jar
Visitor.java:215)
[java] at org.hibernate.ejb.Ejb3Configuration.addMetadataFromVisitor(Ej
b3Configuration.java:253)
[java] at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configurati
on.java:229)
[java] at org.hibernate.ejb.HibernatePersistence.createEntityManagerFac
tory(HibernatePersistence.java:120)
[java] at javax.persistence.Persistence.createEntityManagerFactory(Pers
istence.java:51)
[java] at javax.persistence.Persistence.createEntityManagerFactory(Pers
istence.java:33)
[java] at hello.HelloWorld.main(Unknown Source)
[java] Exception in thread "main" java.lang.IllegalArgumentException: Unkno
wn entity: hello.Message
[java] at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractE
ntityManagerImpl.java:215)
[java] at hello.HelloWorld.main(Unknown Source)
[java] Java Result: 1[/b]

Probably some old Windows and Hibernate EntityManager bug (note the date of the package you are using here...). I'd try it in a directory path without a space in the names.