SUMit Roster Software > Nut's Weekly > February 2002 > Bean | Nederlands · Search... |
Bean |
Monday, 4 February 2002 | December 2001 January 2001 Expired Immigrant Crossroad March 2002 April 2002 | ||||
How does one map an entity from
an ERD
to a Java bean
(= Class)?
The week the continuation, mapping of the entities, in 5 steps:
1. From optionality to specialisationAn optionality can be a clue leading to specialisation. Look for properties such as:
The given simple example does not have any optional attributes.
But Subscription could have had a
2. Analyse top level methodsData analysis will provide sufficient stability in 99% of the cases. Yet, it is still theoretically possible that a subclass has reason to exist solely because of special functionality that wasn't obvious from the data side.
An abundance of conditional processing,
3. Combine classes
Remark: This step is comparable with combining tables in physical database design. 4. Remove exiseSome 'link' classes may still be present, rudiments from the second normal form.An OO model does not need link classes, unlike a physical database:
5. Use cachingUse caching to improve performance. Save CPU time by keeping the right collection of objects at runtime.Remark: This step is comparable with creating indexes in physical database design. |