Method and apparatus for mapping objects to multiple tables of a database

• US 20030212705A1
• Filed: 03/05/2003
• Published: 11/13/2003
• Est. Priority Date: 12/07/1994
• Status: Active Grant

• Current Assignee: Danlel Willhite, Jack Greenfield, Linus Upson, Richard Arthur Williamson
• Original Assignee: Danlel Willhite, Jack Greenfield, Linus Upson, Richard Arthur Williamson
• Inventors: Willhite, Danlel, Williamson, Richard, Upson, Linus, Greenfield, Jack
• Granted Patent: US 7,127,474 B2
• Time in Patent Office: Days
• US Class Current: 707/103R
• CPC Class Codes: G06F 16/2438 Embedded query languages
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: G06F 16/289 Object oriented databases
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure

Abstract

The present invention creates a model that maps object classes in an object-oriented environment to a data source. The model maps the relationship between properties of each object class and data of the data source. The present invention can be used with a data source such as a relational database, user interface, file system, or object-oriented database. An application'"'"'s object classes and data source schema are designed independent of the other since the model can be used to map one to the other. The model is comprised of entities and attributes. An entity maps to an object class and to at least one table of the DBMS. An entity contains attributes either simple or derived. A simple attribute maps to a DBMS column. A derived attribute is a combination of other attributes and does not directly map to a DBMS column. A relationship creates a link between entities of the model. A relationship can be used to flatten an attribute or flatten a relationship. A flattened attribute is an attribute of one entity that is added to another entity. A flattened relationship is created by the elimination of intermediate relationships between two entities. Relationships can be either unidirectional or bi-directional. A unidirectional relationship has a single traversal path that has a source entity and a destination. A bi-directional relationship has two traversal paths. A reflexive relationship can be created using a single entity. The model is used to synchronize object properties and the data of the data source.

Claims

1. A method of mapping objects to a data source comprising the steps of:

defining a plurality of object classes;

defining a schema for said data source;

defining a model that transparently maps said plurality of object classes to said data source schema.

2. The method of claim 1 wherein said data source schema is a database schema.

3. The method of claim 1 wherein said model is comprised of at least one entity that has at least one attribute.

4. The method of claim 3 wherein said attribute is a simple attribute that maps directly to an item of data in said data source.

5. The method of claim 3 wherein said attribute is a derived attribute that does not directly map to an item of data in said data source.

6. The method of claim 3 wherein said model has a plurality of entities and a plurality of relationships between at least two of said plurality of entities.

7. The method of claim 1 further comprising the steps of:

defining a first entity of said model having a first attribute;

defining a second entity of said model;

defining a relationship between said first and second entities;

using said relationship to define said first attribute as an attribute of said second entity.

8. The method of claim 1 further comprising the steps of:

defining a first entity of said model;

defining a second entity of said model;

defining a first relationship between said first and second entities;

defining a third entity of said model;

defining a second relationship between said second and third entities;

defining a third relationship between said first and third entities using said first and second relationships.

9. A method of mapping an object to multiple tables of a database comprising the steps of:

defining a plurality of properties for an object class;

defining a first table having one or more attributes;

defining a second table having one or more attributes;

defining a model having a first entity that corresponds with said first table and a second entity that corresponds with said second table;

creating a relationship between said first and second entities;

defining in said first entity a flattened attribute using said relationship, said flattened attribute being an attribute of said second entity; and

associated said object with said first entity, said plurality of properties corresponding to said attributes of said first entity.

10. The method of claim 9 further comprising the steps of:

generating, using said first entity'"'"'s definition, statements to fetch a record from said database;

instantiating an instance of said object class and loading said properties of said instance with data values contained in said record;

modifying said properties using one or more methods of said object;

generating, using said first entity'"'"'s definition to propagate said modifications made by said object to said first and second tables.