tailieunhanh - Design ejb design patterns phần 8

RDBMS hoặc OODBMS). Điều này cho phép logic kinh doanh là kinh doanh logic và không bị sa lầy với mã kiên trì. Đậu thực thể ẩn tất cả các logic kiên trì từ mã thực thể khách hàng đậu. Container được quản lý. | 180 Chapter Eight RDBMS or OODBMS . This allows business logic to be business logic and not be mired with persistence code. Entity beans hide all the persistence logic from the entity bean client code. Container Managed. When using Container-Managed Persistence CMP entity beans it is a major plus that the container can handle all the persistence logic and O R mapping as well as data caching on a developer s behalf. Persistence logic is notoriously long tedious and bug-ridden. Using CMP is a major plus for EJB developers. Distributed. Entity beans are distributed objects callable via RMI-IIOP from any Java or CORBA client on the network. Secure. Like session beans entity beans business methods can be configured with role-based security checks configurable in the deployment descriptors. Transactional. Entity beans provide developers with fine-grained transaction control. Deployment descriptors can be configured to assign different transaction semantics and isolation levels to different business methods on an entity bean providing automatic declarative transaction control. Components. Entity beans are designed to be components. Deployment descriptors and all the declarative tagging that needs to occur to make an entity bean deployable is intended to make an entity bean into a selfcontained component that is deployable in any J2EE application server without requiring any code changes. These features represent a significant value add that was previously never available on this scale in other distributed frameworks. So with this rich feature set why would people not want to use entity beans Entity Beans and Cognitive Dissonance Cognitive Dissonance is the inner conflict we experience when we do something that is counter to our prior values beliefs and feelings. To reduce our tension we either change our beliefs or explain away our actions. The Complete Idiot s Guide to Psychology Johnston 2000 Cognitive dissonance comes into play because entity beans are designed to be .

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