Oracle Database Discussions

Hi,

I'm making a sales system in Java with Oracle at backed db. I want to know what should be the relation between db users and Application user. Should I make a single database users and put all stuff in that user and then make as many application users as want and then connecting these application users through this single database user. OR Should I make a each oracle db user against single application user. In first case the relation between db and application user will be i to many and in second case it will be one to one.

I want to know what is the preferred approach. weather it depends upon application architect to architect or some other thing should be kept in mind.
Please help me in making this decision. All your opinions with some real examples will be appreciated. If some body has an Experience with Oracle EBS-Suit; I will be glad if you provide me knowledge about Oracle EBS system strategy in this matters.

Regards,

Abbasi