System and Method for Heterogeneous Caching

• US 20070192334A1
• Filed: 04/06/2007
• Published: 08/16/2007
• Est. Priority Date: 01/18/2002
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: BEA Systems Incorporated (Oracle Corporation)
• Inventors: White, Seth
• Granted Patent: US 7,467,166 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/084 with a shared cache
• CPC Class Codes: G06F 12/0875 with dedicated cache, e.g. instruction or stack
• CPC Class Codes: G06F 16/24552 Database cache management
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

The caching of heterogeneous bean sets has been improved from requiring each bean to have its own cache instance to caching the beans in a single cache. The beans can be identified by generating a unique identifier that is a combination of the bean'"'"'s primary key and a self-reference identifier of the bean manager associated with that bean. The average size of a bean set associated with a bean manager can be specified such that the cache allocates memory for that set based on the average size. A callback interface can also be used to shift knowledge of a bean life cycle back to the bean manager.

Claims

1. A method for providing data caching for transactions involving entity beans in an application server, said method comprising the steps of:

reading a data item instance that is contained in a database and is required by a transaction;

holding the data item instance by an entity bean in a cache; and

associating a time-out value with said entity bean in the cache wherein said time-out value determines how long the entity bean should hold the instance of said data item before updating to a new version of said data item.

2. The method of claim 1 further comprising:

acquiring a new instance of said data item by said entity bean after the entity bean has been existence for a period of time equal to its time-out value.

3. The method of claim 2 wherein said entity bean acquires the new instance of said data item by either reading from a database or reading from another entity bean in said cache.

4. The method of claim 2 wherein said new instance of the data item is a newer version of the data item that has been updated during said period of time.

5. The method of claim 1 wherein said time-out value is specified by an element in a deployment descriptor.

6. The method of claim 1 further comprising:

reaching a time-out period by the entity bean wherein said time-out period is specified by an expiration of a period of time equal to said time-out value;

determining, by said entity bean, whether a second entity bean in the cache contains a more recent copy of said data item than said entity bean;

updating the entity bean by reading the data item from said second entity bean if said second entity bean contains a more recent copy, otherwise updating the entity bean by reading from a database.

7. The method of claim 1 wherein said time-out value specifies the number of seconds between Enterprise Java Bean (EJB) Load method calls by a read-only EJB.

8. The method of claim 5 wherein a time-out value of zero indicates that the EJB Load method is called only when the entity bean is brought into the cache.

10. The system of claim 7 wherein said entity bean acquires a new copy of the data item after the entity bean has been in existence for the period of time equal to said time-out value.

11. The system of claim 8 wherein said entity bean acquires the new copy of said data item by either reading from a database or reading from another entity bean in said cache.

12. The system of claim 8 wherein said new instance of the data item is a potentially newer version of the data item that has been updated during said period of time.

13. The system of claim 7 wherein said time-out value is specified by an element in an application level deployment descriptor of said cache.

14. The system of claim 7 wherein said entity bean is configured to:

reach a time-out period by the entity bean wherein said time-out period is specified by an expiration of a period of time equal to said time-out value;

determine whether a second entity bean in the cache contains a more recent copy of said data item than said entity bean; and

update the copy of the data item by reading from said second entity bean if said second entity bean contains a more recent copy, otherwise update the copy of the data item by reading from a database.

15. The system of claim 7 wherein said time-out value specifies the number of seconds between Enterprise Java Bean (EJB) Load method calls by a read-only EJB.

16. The system of claim 13 wherein a time-out value of zero indicates that the EJB Load method is called only when the entity bean is brought into the cache.

9. A system for providing data caching for transactions involving entity beans, said system comprising:

a database containing a plurality of data items accessed by one or more transactions;

a cache that includes a plurality of entity beans, each entity bean storing a copy of a data item for use by said transactions; and

a time-out value associated with each said entity bean wherein said time-out value specifies a period of time that said entity bean should hold the copy of the data item before updating to a new version of said data item.

17. A computer readable medium having instructions stored thereon which when executed by one or more processors cause a system to perform the steps of:

reading a data item instance that is contained in a database and is required by a transaction;

holding the data item instance by an entity bean in a cache; and

associating a time-out value with said entity bean in the cache wherein said time-out value determines how long the entity bean should hold the instance of said data item.