Mick, The design pattern doesn't states how DAO's are to be implemented, but rather what problem they are supposed to solve.
One reason why you might not want a DAO to be a singleton is if you instantiate one with an Connection. This might be done to avoid having to pass the Connection to each method. I think your implementation is appropriate. It makes sense performance wise and it is also intuitively more OO. Why create a new instance of an object if it does not maintain state? My .02, robert > -----Original Message----- > From: news [mailto:[EMAIL PROTECTED] Behalf Of Mick Wever > Sent: Sunday, August 24, 2003 12:59 PM > To: [EMAIL PROTECTED] > Subject: Is singleton DAO acceptable? -- Best Practices > > > All the DAO examples I've read have DaoFactory classes that always return > a new DAO instance, and typically the action using it keeps a handle to it > for that session. > > The DAOs that I've created have no state or instance variables, and get > their connections from a synchronized pool (and always returning the > connection within the same method call). So, since they are > multi-threaded, it makes sense to me performance wise it is better > for the factory to always return a singleton instance of the DAO. > This single instance of the DAO is shared across all sessions in > the JVM. > (Note this is not the traditional usage of singleton where the singleton > itself is responsible for returning the single instance through a static > method). > > My question is, is this such a good idea? Am I missing or misunderstanding > something crucial about the DAO Design Pattern? > > Mick. > > -- > <BR/> > "We all may have come on different ships, but we’re in the same > boat now." > Martin Luther King. Jr. > <BR/> > --- <a > href=http://www.harryspractice.com.au>www.harryspractice.com.au</a> --- > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
