Detailed Comparison of ODMG 3.0 and JDO
This table shows a summary of the similarities and differences between the two approaches to transparent persistence: ODMG 3.0 and JDO. It is from a presentation at JavaOne by Heiko Bobzin of POET Software.
|Transparent Persistence||Transparent Persistence|
|Persistence by Reachability||Persistence by Reachability|
|Java, C++, and Smalltalk Language Bindings on top of ODMG object model||Tight integration with Java object model|
|Vendor specific interfaces||PersistenceCapable interface|
|Collection factory for five basic collections||Collection factory “by Example”, Second Class Objects|
|Object identity managed by database system||Three identity models (more)|
|Objects live until transaction completes||Objects can live as long as PersistenceManager (more)|
|Objects can not be accessed after transaction completes||API allows the setting of properties|
|Callbacks not defined||Callbacks for load, store, delete, and clear|
|Databases and Transactions|
|Easy to use but proprietary database and transaction management||Databases, connections and transactions fit into other Java APIs|
|No distributed transactions defined||Support for distributed transactions|
|Vendor specific extensions for managed environments (EJB)||Support for managed environments (EJB)|
|Vendor specific extension for optimistic locking||Optimistic locking is optional API|
|Explicit locking of objects||No explicit locking -- locks set automatically|
|OQL: an extensive object query language||Queries based on Java programming language — JDOQL (more)|
|Complex query expressions||Simple filter strings|
|Results can be compositions, projections or just an integer||Results are always collections of persistence capable objects|
|Class name is part of query string||Class objects explicitly used as parameters|
|No imports or name scope||Imports, "this", named parameters|
This table, copyright © 2001 FastObjects by Poet, used with permission.
For more information on transparent persistence, see:
- Transparent persistence for object databases
- Transparent persistence for relational databases using object-relational mapping products
For more information on ODMG 3.0 and JDO as well as other database specifications, see the related content below.
More on the general topic: DBMS Standards
- Java Data Objects (JDO)
- ODMG 3.0
- Summary Comparison of DBMS Standards
Author: Douglas K Barry
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