Notification of aspect value change in object-oriented programming

• US 5,819,281 A
• Filed: 02/26/1996
• Issued: 10/06/1998
• Est. Priority Date: 02/26/1996
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Electronic Data Systems Corporation (Perspecta, Inc.)
• Inventors: Cummins, Fred A.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): RONES, CHARLES
• Application Number:
  US08/606,983
• Time in Patent Office: 953 Days
• Field of Search: 395/614, 395/200.51, 395/617, 395/500, 395/702, 395/683, 707/2, 707/103
• US Class Current: 1/1
• CPC Class Codes: G06F 16/289 Object oriented databases
• CPC Class Codes: G06F 9/542 Event management; Broadcasting; Multicasting; Notifications
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure

Abstract

An object-oriented programming language includes support for encapsulation of aspects and for change notification for aspect values. These features are then used to implement various change notification mechanisms. In general, a notification request for change in an aspect value in a target object is forwarded to any object (which may be the same object or another object) having aspects from which the aspect value is computed, derived, or replicated.

Claims

1. An active view object for use in an object-oriented software system, comprising:

at least one aspect with a derived aspect value derived from an aspect in an underlying object;

an associated object protocol; and

a method that complies with a notification request to said active view object for a change in said derived aspect value by generating a notification request to said underlying object.

2. A method of using an object-oriented programming language to define an active view object, for use in a computer system, comprising the steps of:

receiving a view object definition, said view object definition having an aspect with a derived aspect value derived from an aspect of an underlying object and having an associated object protocol; and

generating programming code for a method associated with said view object such that a notification request to said view object for a change in said derived aspect value will generate a notification request to said underlying object.

3. A method of using object-oriented programming to provide change notification for an active view object having a derived aspect value that is derived from an aspect of an underlying object, for implementation on a computer system, comprising the steps of:

receiving a notification request to said view object requesting notice of a change in the value of said derived value;

sending a notification request to said underlying object; and

attaching said notification request to said underlying object such that said underlying object will deliver a change notification message to said view object when a value of said aspect changes;

wherein the above steps use object protocols during execution of said object-oriented programming.

4. The method of claim 3, wherein said view object has methods for translating an interface.

5. The method of claim 3, wherein said view object has methods for providing an abstraction of a complex structure.

6. The method of claim 3, wherein said view object excludes access to aspect values of said underlying objects.

7. A method of using object-oriented programming to provide a shared object having one or more aspects, for implementation on a computer system, comprising the steps of:

creating at least one proxy object for said shared object in a client environment, said proxy having the same stored aspect values as said shared object;

providing said proxy object with a message protocol such that if said proxy object receives a notification request it then automatically sends a notification request to said shared object requesting notice of a change in a value of an aspect of said shared object; and

attaching said notification request to said shared object such that said shared object will deliver a change notification message to said proxy object when said value changes, thereby causing said aspect value in said proxy object to be updated;

wherein the above steps use object protocols during execution of said object-oriented programming.

8. The method of claim 7, wherein at least one of said aspect values is a computed value, and further comprising the step of sending notification requests to each aspect used to obtain said computed value.

9. A method of using object-oriented programming to provide change notification of aspect values for implementation on a computer system that stores objects having at least one attribute aspect or at least one relationship aspect, comprising the steps of:

receiving a notification request from a requester object to a target object, wherein said notification request is the same for stored and computed aspect values of said target object;

if said aspect has a computed value, identifying the aspects used to compute said computed value, based on references in a computation expression;

sending notification requests to any object, which may be one or more objects other than the target object, having aspects referenced in said computation expression; and

attaching said notification requests to said objects having aspects referenced in said computation expression such that a change notification message will be delivered when a value used to compute said computed value changes;

wherein the above steps use object protocols during execution of said object-oriented programming.

10. The method of claim 9, wherein said attaching step is performed in a manner that permits said notification request to generate said notification messages.

11. The method of claim 9, wherein said software system is a compiled system and said identifying step is a result of identifying said computation expression during compilation.

12. The method of claim 9, wherein said software system is an interpreted system and wherein said computation expression is identified at run time.

13. The method of claim 9, wherein said requester object is the recipient of said change notification message.

14. The method of claim 9, wherein said notification request identifies an object other than said requestor object as the recipient of said change notification message.

15. The method of claim 9, wherein aspects referenced in said computation expression are indirectly referenced.

16. A method of using an object-oriented programming language to define an object, said object having at least one computed aspect value, for use in a computer system, comprising the steps of:

receiving an object definition, said object definition having at least one aspect with an aspect value computed by means of a computation expression and having an associated object protocol;

receiving a notification request for notice of a change in said aspect value, wherein said notification request is the same for stored and computed values; and

generating programming code for a method associated with said object such that said notification request will generate a notification request to any aspect used in said computation expression, said generating step being performed by identifying the aspects used to compute said computed value, based on references in a computation expression;

sending notification requests to other objects having aspects referenced in said computation expression; and

attaching said notification requests to said objects having aspects referenced in said computation expression such that a change notification message will be delivered when a value used to compute said computed value changes.

17. An object for use in an object-oriented software system, comprising:

at least one aspect, said aspect representing an attribute or relationship of said object, and said aspect having a value computed by means of a computation expression;

an associated object protocol; and

a method that complies with a notification request to said object for a change in said computed aspect value by generating a notification request to aspects used in said computation expression, wherein said method has means for identifying the aspects used to compute said computed value, based on references in a computation expression;

sending notification requests to other objects having aspects referenced in said computation expression; and

attaching said notification requests to said objects having aspects referenced in said computation expression such that a change notification message will be delivered when a value used to compute said computed value changes.