Just in case no one else has already pointed this out, I think there is another error in the EJB Design patterns book that is not documented in the current Errata.
Sorry if this is posted to the wrong place, but the link on the website for reporting errors in the book is actually not working.
See the Appendix, Page 232, sample code for Business Delegate class.
In the method addForum see the following line of code in the try block:
return getEJB().sb.addForum(categoryPK, forumTitle, summary);
Note the presence of .sb private member data.
I think this code should really be as follows:
return getEJB().addForum(categoryPK, forumTitle, summary);
Because the getEJB method already returns the sb. Or, perhaps alternatively this could be:
return this.sb.addForum(categoryPK, forumTitle, summary);
Although this would not be as robust as the first suggestion...
In addition, the sample code for this Business Delegate class is not present in the ZIP file download.
Nonetheless, thank you Floyd for an excellent book. I have recommended it to several people.