Can l make an instance of EJB home handler / Datasource shared by EJB objs

Question

all ejb guru
As far as l know, it is general rule of thumb to cache the EJB home handlers and datasource object at EJB bean instance. But can l go a step further, make the same instance of EJB home handlers and datasource object shared by more than 1 EJB bean instance ?
( l checked out the methods of javax.ejb.EJBhome and javax.sql.DataSource. They are not declared as synchronized. It seems to me that EJB home handlers and datasource object are not thread safe and not suitable for being shared. Even they are thread-safe, if they are shared by 1+ EJB bean instance. Sharing EJB home handlers and datasource object may interfere the thread management of EJB container. Am l correct ? )
It is highly appreciated someone can share with me your insight in this issue.
thanks & regards
Danny

Answer 1

Okay, you got me there. However, it's usually a better practice to start a new thread with your specific question instead of resurrecting old threads that (obviously) nobody cared enough to answer.
DataSources are retrieved from the container via JNDI. You may (generally) cache them in order to alleviate the JNDI lookup without worrying about Threads, as there is only (usually) one DataSource object per server (or node in a cluster). Do not cache (in your code) the Connection objects obtained from the DataSource - always close them in order to return them to the pool maintained by the DataSource.
Caching EJB HomeHandles is the accepted manner of avoiding repeated JNDI calls to locate EJBs. Typically, extracting the EJBHome from the HomeHandle re-initializes whatever network operations are embedded in the EJBHome object(s) by the vendor's implementation. Once again, you do not necessarily need to worry about Threads - the container and vendor implementation is already taking care of that for you, transparently.
Think about it: if there were Threading issues, even retrieving the above objects via JNDI would ensure that J2EE application servers wouldn't be Thread safe and all operations would be, essentially, blocked each time. Obviously, this is not the case since both DataSources and EJBHome objects can have multiple clients using them simultaneously. Just because there's not explicit synchronized tag on any of the methods defined in these interfaces doesn't mean they're single-Thread objects.