Method and apparatus for information state management

• US 5,842,223 A
• Filed: 07/03/1995
• Issued: 11/24/1998
• Est. Priority Date: 07/03/1995
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Bristor, David M.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): LEWIS, CHERYL RENEA
• Application Number:
  US08/497,526
• Time in Patent Office: 1,240 Days
• Field of Search: 395/185.05, 395/185.02, 395/614, 395/600, 395/650, 707/100, 707/101, 707/103, 707/204
• US Class Current: 1/1
• CPC Class Codes: G06F 9/4488 Object-oriented
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

Data elements which can be combined to define a state are defined by respective attributes of an attribute set. An attribute includes an identifier, a data type, an accessor, and procedures for storing and retrieving values of the data element. A context includes at most one value for each attribute of an attribute set. Different contexts can have different respective values for the same attribute. Since an attribute includes a data type and procedures for storing and retrieving values of the attribute, type checking error detection mechanisms of the computer instruction language in which the attributes are implemented remain in effect. In addition, attribute values are stored in an ordered structure, e.g., an ordered list, in each context and the location within the ordered structure at which an attribute value corresponding to a particular attribute is stored in the particular attribute. As a result, attribute values are accessed within contexts in a particularly efficient manner. Attribute sets are extensible at run time such that attributes can be added to an attribute list during execution of a computer process in which the attribute set is implemented.

Claims

1. A method for accessing a data element in a memory of a computer system, the method comprising:

forming in the memory an attribute which defines the data element;

including the attribute in an attribute set structure which includes zero or more other attributes and to which additional attributes can subsequently be added;

forming in the memory one or more contexts, each of which can include a value of the data element;

including in the attribute an access procedure, execution of which accesses the value of the data element within a selected one of the one or more contexts; and

executing the access procedure while specifying the selected context to thereby access the value of the selected context.

2. The method of claim 1 further comprising:

including in the attribute a data type according to which values of the data element are accessed.

3. The method of claim 1 further comprising:

including in the attribute an accessor which specifies a location within each of the contexts of the respective values of the data element.

4. The method of claim 1 wherein execution of the access procedure stores the value in the selected context.

5. The method of claim 1 wherein execution of the access procedure retrieves the value from the selected context.

6. The method of claim 1 wherein the step of executing the access procedure comprises:

supplying as an argument the selected context.

7. The method of claim 1 further comprising:

detecting as an error condition an attempted access from within the selected context of a value of an attribute which is not included in the attribute set structure.

8. The method of claim 1 further comprising:

associating the selected context with the attribute set structure.

9. The method of claim 8 further comprising:

detecting as an error condition an attempted access from within the selected context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.

10. The method of claim 1 further comprising:

including in each of the contexts at most one value for each of the attributes included in the attribute set structure, the attributes including the attribute, the other attributes, and the additional attributes.

11. A method for accessing a data element in a memory of a computer system, the method comprising:

forming in the memory an attribute which defines the data element;

including the attribute in an attribute set structure which includes zero or more other attributes;

including in the attribute an accessor which specifies a location within a context of a value of the data element; and

accessing a value of the data element within a context, the step of accessing comprising;

accessing the value from within a specified context at the location specified by the accessor.

12. The method of claim 11 wherein one or more additional attributes can be added to the attribute set structure.

13. The method of claim 11 wherein the accessor is an array index.

14. The method of claim 11 wherein the accessor is an offset into a collection of one or more values within the context which correspond to one or more respective data elements.

15. The method of claim 11 further comprising:

including in the attribute an access procedure, execution of which accesses the value of the data element within the context; and

executing the access procedure while specifying the context to thereby access the value of the data element.

16. The method of claim 15 further comprising:

including in the attribute a data type according to which values of the data element are accessed.

17. The method of claim 11 wherein the accessor specifies a location within a collection of one or more values within the context.

18. The method of claim 11 further comprising:

detecting as an error condition an attempted access of a value from within the specified context of an attribute which is not included in the attribute set structure.

19. The method of claim 11 further comprising:

associating the specified context with the attribute set structure.

20. The method of claim 19 further comprising:

detecting as an error condition an attempted access from within the specified context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.

21. A structure for maintaining state information in a memory of a computer system, the structure comprising:

one or more contexts, each of which can include a value of a data element of the state;

an attribute, which is operatively coupled to the contexts and which is formed in the memory and which defines the data element, the attribute comprising;

an access procedure, execution of which accesses the value of the data element within a specified one of the contexts;

an attribute set structure which includes the attribute and zero or more other attributes; and

means, operatively coupled to the attribute set structure, for adding one or more additional attributes to the attribute set structure.

22. The structure of claim 21 wherein the attribute further comprises:

a data type, operatively coupled to the access procedure, according to which the value of the data element is accessed.

23. The structure of claim 21 wherein the attribute further comprises:

an accessor operatively coupled to the access procedure; and

further wherein the access procedure accesses the value of the attribute within the specified context by accessing a position specified by the accessor within a collection of at most one value for each of one or more attributes.

24. The structure of claim 21 wherein execution of the access procedure stores the value of the data element in the specified context.

25. The structure of claim 21 wherein execution of the access procedure retrieves the value of the data element from the specified context.

26. The structure of claim 21 further comprising:

an error detection mechanism, operatively coupled to the access procedure, for detecting as an error condition an attempted access of a value from within the specified context of an attribute which is not included in the attribute set structure.

27. The structure of claim 21 wherein the specified context further comprises:

an association with the attribute set structure.

28. The structure of claim 27 wherein the association of the specified context is a pointer to the attribute set structure.

29. The structure of claim 27 further comprising:

an error detection mechanism, operatively coupled to the access procedure and to the association of the specified context with the attribute set structure, for detecting as an error condition an attempted access from within the specified context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.

30. A structure for maintaining state information in a memory of a computer system, the structure comprising:

an attribute set structure which is formed in the memory and which includes one or more attributes, wherein each of the attributes defines a respective data element of the state and comprises;

an accessor which specifies a location within each of one or more contexts, each of which comprises at most one data element value for each of the attributes, at which a value of the data element of the attribute is located.

31. The structure of claim 30 further comprising:

means, operatively coupled to the attribute set structure, for adding one or more additional attributes to the attribute set structure.

32. The structure of claim 30 wherein the accessor of each attribute is an array index.

33. The structure of claim 30 wherein the accessor is an offset into the at most one value of each of the attributes within the context.

34. The structure of claim 30 wherein each of the attributes further comprises:

an access procedure, which is operatively coupled to the accessor and execution of which accepts specification of a selected one of the contexts and accesses the value of the data element within the selected context.

35. The structure of claim 34 wherein the attribute further comprises:

a data type, operatively coupled to the access procedure, according to which the value of the data element is accessed.

36. The structure of claim 34 further comprising:

an error detection mechanism, operatively coupled to the access procedure, for detecting as an error condition an attempted access of a value from within the specified context of an attribute which is not included in the attribute set structure.

37. The structure of claim 34 wherein the specified context further comprises:

an association with the attribute set structure.

38. The structure of claim 37 wherein the association of the specified context is a pointer to the attribute set structure.

39. The structure of claim 37 further comprising:

an error detection mechanism, operatively coupled to the access procedure and to the association of the specified context with the attribute set structure, for detecting as an error condition an attempted access from within the specified context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.

40. A computer-readable memory which includes a structure for maintaining state information in a computer system, the structure comprising:

one or more contexts in the memory, each of which can include a value of a data element of the state;

an attribute in the memory, which is operatively coupled to the contexts and which defines the data element, the attribute comprising;

an access procedure, execution of which accesses the value of the data element within a specified one of the contexts;

an attribute set structure in the memory which includes the attribute and zero or more other attributes; and

means, operatively coupled to the attribute set structure, for adding one or more additional attributes to the attribute set structure.

41. The memory of claim 40 wherein the attribute further comprises:

a data type, operatively coupled to the access procedure, according to which the value of the data element is accessed.

42. The memory of claim 40 wherein the attribute further comprises:

an accessor operatively coupled to the access procedure; and

further wherein the access procedure accesses in the memory the value of the attribute within the specified context by accessing a position specified by the accessor within a collection in the memory of at most one value for each of one or more attributes.

43. The memory of claim 40 wherein execution of the access procedure stores the value of the data element in the specified context.

44. The memory of claim 40 further comprising:

an error detection mechanism in the memory, operatively coupled to the access procedure, for detecting as an error condition an attempted access of a value from within the specified context of an attribute which is not included in the attribute set structure.

45. The memory of claim 40 wherein the specified context further comprises:

an association in the memory with the attribute set structure.

46. The memory of claim 45 further comprising:

an error detection mechanism in the memory, operatively coupled to the access procedure and to the association of the specified context with the attribute set structure, which detects as an error condition an attempted access of the memory within the specified context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.

47. The memory of claim 40 wherein execution of the access procedures retrieves the value of the data element from the specified context.

48. A computer-readable memory in which a structure maintains state information in a computer system, the structure comprising:

an attribute set structure which is formed in the memory and which includes one or more attributes, wherein each of the attributes defines a respective data element of the state and each of which comprises;

an accessor which specifies a location within each of one or more contexts in the memory, each of which comprises at most one data element value for each of the attributes, at which a value of the data element of the attribute is located.

49. The memory of claim 48 further comprising:

means, operatively coupled to the attribute set structure, for adding one or more additional attributes to the attribute set structure.

50. The memory of claim 48 wherein the accessor of each attribute is an array index.

51. The memory of claim 48 wherein the accessor is an offset into the at most one value of each of the attributes within the context.

52. The memory of claim 48 wherein each of the attributes further comprises:

an access procedure, which is operatively coupled to the accessor and execution of which accepts specification of a selected one of the contexts and accesses the value of the data element within the selected context.

53. The memory of claim 52 wherein the attribute further comprises:

a data type, operatively coupled to the access procedure, according to which the value of the data element is accessed.

54. The memory of claim 52 further comprising:

an error detection mechanism in the memory, operatively coupled to the access procedure, for detecting as an error condition an attempted access within the memory of a value from within the specified context of an attribute which is not included in the attribute set structure.

55. The memory of claim 52 wherein the specified context further comprises:

an association with the attribute set structure.

56. The memory of claim 55 further comprising:

an error detection mechanism, operatively coupled to the access procedure and to the association of the specified context with the attribute set structure, for detecting as an error condition an attempted access in the memory within the specified context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.

57. A computer system comprising:

a memory;

a structure formed in the memory for maintaining state information in a computer system, the structure comprising;

one or more contexts in the memory, each of which can include a value of a data element of the state;

an attribute in the memory, which is operatively coupled to the contexts and which defines the data element, the attribute comprising;

an access procedure, execution of which accesses the value of the data element within a specified one of the contexts;

an attribute set structure in the memory which includes the attribute and zero or more other attributes; and

means, operatively coupled to the attribute set structure, for adding one or more additional attributes to the attribute set structure.

58. The computer system of claim 57 wherein the attribute further comprises:

a data type, operatively coupled to the access procedure, according to which the value of the data element is accessed.

59. The computer system of claim 57 wherein the attribute further comprises:

an accessor operatively coupled to the access procedure; and

further wherein the access procedure accesses in the memory the value of the attribute within the specified context by accessing a position specified by the accessor within a collection in the memory of at most one value for each of one or more attributes.

60. The computer system of claim 57 wherein execution of the access procedure stores the value of the data element in the specified context.

61. The computer system of claim 57 further comprising:

an error detection mechanism in the memory, operatively coupled to the access procedure, for detecting as an error condition an attempted access of a value from within the specified context of an attribute which is not included in the attribute set structure.

64. The computer system of claim 57 wherein execution of the access procedure retrieves the value of the data element from the specified context.

62. The computer system of claim wherein the specified context further comprises:

an association in the memory with the attribute set structure.

63. The computer system of claim 62 further comprising:

an error detection mechanism in the memory, operatively coupled to the access procedure and to the association of the specified context with the attribute set structure, which detects as an error condition an attempted access of the memory within the specified context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.

65. A computer system comprising:

a memory;

a structure formed in the memory for maintaining state information in a computer system, the structure comprising;

an attribute set structure which is formed in the memory and which includes one or more attributes, wherein each of the attributes defines a respective data element of the state and each of which comprises;

an accessor which specifics a location within each of one or more contexts in the memory, each of which comprises at most one data element value for each of the attributes, at which a value of the data element of the attribute is located.

66. The computer system of claim 65 wherein the structure further comprises:

means, operatively coupled to the attribute set structure, for adding one or more additional attributes to the attribute set structure.

67. The computer system of claim 65 wherein each of the attributes further comprises:

an access procedure, which is operatively coupled to the accessor and execution of which accepts specification of a selected one of the contexts and accesses the value of the data element within the selected context.

68. The computer system of claim 67 wherein the attribute further comprises:

a data type, operatively coupled to the access procedure, according to which the value of the data element is accessed.

69. The computer system of claim 67 wherein the structure further comprises:

an error detection mechanism in the memory, operatively coupled to the access procedure, for detecting as an error condition an attempted access within the memory of a value from within the specified context of an attribute which is not included in the attribute set structure.

70. The computer system of claim 67 wherein the specified context further comprises:

an association with the attribute set structure.

71. The computer system of claim 70 wherein the structure further comprises:

an error detection mechanism, operatively coupled to the access procedure and to the association of the specified context with the attribute set structure, for detecting as an error condition an attempted access in the memory within the specified context of a value of an attribute which is included in a second attribute set structure, which is different from the first-mentioned attribute structure.