Hi Vlad,
in your first posting you wundered about entity EJB vs. DAO, but now I read about business logic:
Originally posted by Vlad eroshin:
He strongly promotes the idea that Business logic must be deployment independent and selfcontained - meaning that
For clustered servers you might prefere a session EJB being a pure/poor Session Facade. That is all what JNDI goes to - not much.
For doing the business logic you may choose remote Session EJBs as well (allowing for further clustering of parts of the business logic if via remote interface), or local Session EJBs, or just local POJOs, all trhee realizing the Business Tier.
This Business Tier accesses Entity EJBs and / or DAOs of the Enterprise Integration / Data Access Tier that in turn access db tables or other resources in EIS / Data Tier.
Originally posted by Vlad eroshin:
... Derec C. Ashmore. He makes two separate layers - Deployment Layer and Business Logic layer. In Deployment layer he puts all the EJBs and Business Logic he implements as plain java objects.
Is he talking about
tiers or about
layers? In Suns three dimensional cube tiers are vertical (Client, Presentation, Business, Data Access, Data Tier) and layers are horizontal like transport layer.
In my world his Deployment layer would just be the Session Facade EJB mentioned above for Business Tier, right?
And for Data Access Tier there would be a Deployment layer only if using EJBs, not for DAOs?
How Deployment layer is defined? That what we need a deployment descriptor for?
Thomas