Summary of Business Tier Patterns

The Presentation Tier will access the Business Tier via Business Delegate .
Business Delegate inturn access EJB by looking up using Service Locator.
The EJB [Session Facade] or the WebService End Point representing the Deployment Layer communicates to Application Service Layer [Algorithms, Main Logic].
Application Service Layer access Entities [Business Objects].

The communication between Tiers happen using Transfer Objects [not shown in the figure].
The Deployment Layer can also communicate to Business Objects directly and not via Application Service Layer depending on the Transaction Design.