2.7. Java EE Declarative Security Overview

The J2EE security model is declarative in that you describe the security roles and permissions in a standard XML descriptor rather than embedding security into your business component. This isolates security from business-level code because security tends to be more a function of where the component is deployed than an inherent aspect of the component's business logic. For example, consider an Automated Teller Machine (ATM) that is to be used to access a bank account. The security requirements, roles and permissions will vary independent of how you access the bank account, based on what bank is managing the account, where the ATM is located, and so on.
Securing a J2EE application is based on the specification of the application security requirements via the standard J2EE deployment descriptors. You secure access to EJBs and web components in an enterprise application by using the ejb-jar.xml and web.xml deployment descriptors.