You have a remote client that wants to iterate over a large results
- You want to avoid the overhead of using EJB finder methods for large
- You want to implement a read-only use-case that does not require a
- You want to provide the clients with an efficient search and iterate
mechanism over a large results set.
- You want to maintain the search results on the server side.
Use a Value List Handler to search, cache the results,
and allow the client to traverse and select items from the results.
- POJO Handler Strategy
- Value List Handler Session Façade Strategy
- Value List from Data Access Object Strategy
- Provides efficient alternative to EJB finders
- Caches search results
- Provides flexible search capabilities
- Improves network performance
- Allows deferring entity bean transactions
- Promotes layering and separation of concerns
- Creating a large list of Transfer Objects can be expensive
- Iterator [GoF]
This Value List Handler uses the Iterator pattern, described in the
GoF book, Design Patterns: Elements of Reusable Object-Oriented Software.
- Data Access Object
This Value List Handler uses the Data Access Object to perform searches
using either the DAO Transfer Object Collection strategy to obtain a
collection of transfer objects or using the DAO RowSet Wrapper List
strategy to obtain a custom List implementation.
- Session Façade
The Value List Handler is often implemented as a specialized version
of the Session Façade responsible for managing the search results
and providing a remote interface. Some applications might have Session
Façades that expose other business methods and also include the
functionality of the Value List Handler. However, it might be better
to keep the list handling functionality of the Value List Handler separate
from the business methods of a Session Façade. Thus, if the Value
List Handler needs a remote interface, provide a dedicated session bean
implementation that encapsulates and facades the Value List Handler.