Implementing persistent object services (POS) on top of a relational database

• US 6,470,354 B1
• Filed: 08/05/1999
• Issued: 10/22/2002
• Est. Priority Date: 08/05/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Murthy, Suresh Narayana, Rulong, Gordon Scott, Xu, Tingting, Aldridge, Amy S.
• Primary Examiner(s): Breene, John
• Assistant Examiner(s): Ali, Mohammad
• Application Number:
  US09/368,698
• Time in Patent Office: 1,174 Days
• Field of Search: 707/3-4, 707/102-104, 709/102, 709/203, 709/217, 709/250, 717/6.5
• US Class Current: 1/1
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: G06F 16/289 Object oriented databases
• CPC Class Codes: Y10S 707/954 Relational
• 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
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

A persistent object service (POS) that interfaces to a set of one or more relational database management systems. A persistent object is mapped to one or more tables in a relational database based on the object'"'"'s attribute types and the object'"'"'s relationships with other objects. If the object inherits from another object, the mapping creates multiple tables, a top level table for base attributes, and a set of one or more child tables that contain extended attributes of the inherited objects. A routine for storing an object converts persistent object operations to a sequence of SQL statements for storing the object in the relational database.

Claims

1. A method for interfacing an object-oriented application to a set of relational databases, comprising the steps of:

mapping persistent objects to a set of relational database tables including a top level table and a set of one or more child tables, wherein each object is mapped to one or more tables based on the object'"'"'s attributes and the object'"'"'s relationships with other objects, wherein the top level table stores base attributes and a given child table stores only extended attributes of inherited objects;

in response to a request from the application to store an object in a given one of the relational databases, converting persistent object operations to a sequence of SQL statements to enable the object to be stored in the relational database; and

in response to a request from the application to restore the object from the given one of the relational databases, retrieving object at tribute information from the relational database and generating the object.

2. The method as described in claim 1 wherein the step of converting includes:

extracting object information relating to an object from a stream;

constructing an insert statement from the extracted object information;

responsive to a failure of the insert statement, constructing an update statement from the extracted object information; and

storing the object information.

3. A computer program product in a computer readable medium for interfacing an object-oriented application to a set of relational databases, comprising the steps of:

means for mapping persistent objects to a set of relational database tables including a top level table and a set of one or more child tables, wherein each object is mapped to one or more tables based on the object'"'"'s attributes and the object'"'"'s relationships with other objects, and wherein the top level table stores base attributes and a given child table stores only extended attributes of inherited objects;

means responsive to a request from the application to store an object in a given one of the relational databases for converting persistent object operations to a sequence of SQL statements to enable the object to be stored in the relational database; and

means responsive to a request from the application to restore the object from the given one of the relational databases for retrieving object attribute information from the relational database and generating the object.

4. In a distributed object oriented computer environment having a set of one or more relational database management systems, the improvement comprising:

means for mapping persistent objects to a set of relational database tables including a top level table and a set of one or more child tables, wherein each object is mapped to one or more tables based on the object'"'"'s attributes and the object'"'"'s relationships with other objects, and wherein the top level table stores base attributes and a given child table stores only extended attributes of inherited objects;

means responsive to a request to store an object in a given one of the relational databases for converting persistent object operations to a sequence of SQL statements to enable the object to be stored in the relational database; and

means responsive to a request to restore the object from the given one of the relational databases for retrieving object attribute information from the relational database and generating the object.

5. In a relational database management system (RDBMS), the improvement comprising:

means for mapping persistent objects to a set of relational database tables including a top level table and a set of one or more child tables, wherein each object is mapped to one or more tables based on the object'"'"'s attributes and the object'"'"'s relationships with other objects, and wherein the top level table stores base attributes and a given child table stores only extended attributes of inherited objects;

means responsive to a request to store an object in a given one of the relational databases for converting persistent object operations to a sequence of SQL statements to enable the object to be stored in the relational database; and

means responsive to a request to restore the object from the given one of the relational databases for retrieving object attribute information from the relational database and generating the object.