JPH06149646A - Object directional data base management system - Google Patents

Abstract

PURPOSE:To provide an object directional data base management system capable of executing dynamic type inspection considering succession relation. CONSTITUTION:When a management means 11 judges that a class object expressing the attribute type of the 1st succeeding object expresses the same type as that of a class object expressing the attribute type of the 2nd succeeding object or a class object succeeding the attribute type of the class object in respect to the contents of a data base file 20 stored in a main memory 30, a type inspecting means 12 executes operation for substituting the 1st succeeding object for the attribute of the 2nd succeeding object, and at the time of judging that the class object expressing the attribute type of a succeeding object expresses the same type as that of a class object expressing the element type of an integrated object or a class object succeeding the element type of the class object, executes operation for inserting the succeeding object into the integrated object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object oriented database management system.

[0002]

2. Description of the Related Art Conventionally, in an object-oriented database management system, in order to guarantee data consistency, a type is declared for the persistent object itself, its attributes, or elements of an aggregate object, and the data of the type is declared based on the type. I try to do an inspection. That is, static type checking is performed before execution by a compiler or preprocessor for assigning values to attributes of persistent objects and inserting elements into aggregate objects.

In addition to such static type checking, there has been proposed a type which performs dynamic type checking. As a system for performing this dynamic type checking, "The GemStone Data Management System (" The GemStone
Data Management System "):" Object Oriented Concepts, Database "
s, and Applications ”) Edited by (W.Kim, FHLoch
ovsky) 1989. (ACMpress.) pp238-pp308 ”(referred to as reference 1).

Further, as a system adapted to utilize the type information, there is a system disclosed in Japanese Patent Laid-Open No. 3-50646. In the publication disclosed in this publication, the type (type) of the attribute of the object is held and the type (type) information is used when updating the attribute.

The basic concept of the object-oriented database is as follows: (1) "" Basic concept of object-oriented database "
(Katsumi Tanaka Information Processing Vol.32 No.5 pp500 ~ 513 May
1991) "(2)" Architecture of object-oriented database management system "(Kenfumi Makinouchi, Information Processing Vol.32
No5 pp514 to 522 May 1991) ”is known.

As a system realizing an object-oriented database management system, Japanese Patent Laid-Open No. 3-137
The one disclosed in Japanese Patent Publication No. 730 is known.

[0007]

However, the above-mentioned conventional static type checking has the following two problems. (A) It is impossible to perform sufficiently strict type inspection by a mechanism such as type conversion. (B) A dynamic type change in which the type definition is changed at execution cannot be dealt with.

Further, in the system for performing dynamic type checking described in the above-mentioned Document 1, since the type information does not describe nor suggest the inheritance relationship, the inheritance relationship is taken into consideration. No dynamic type checking can be done.

Further, in the above-mentioned Japanese Patent Laid-Open No. 3-50646, the type information is not used for type checking and the inheritance relation is not taken into consideration. No dynamic type checking can be done.

As described above, in the related art, since it is impossible to perform a dynamic type check in consideration of inheritance relationships, it is difficult to prevent incorrect data substitution or insertion.

It is an object of the present invention to provide an object-oriented database management system capable of performing dynamic type checking in consideration of inheritance relationships.

[0012]

In order to achieve the above object, in the object-oriented database management system of the first invention, a plurality of objects and the types of attributes of the objects respectively corresponding to the objects are included. Management means for managing a class object that holds type information and also information about inheritance relation of the type; and when associating a first object with a second object among the plurality of objects, A type checking means for checking the type based on the class object corresponding to each object.

In the object-oriented database management system of the second invention, a plurality of objects and type information corresponding to each of the objects and including the attribute type of the object are held, and information on the inheritance relation of the type is held. Can also hold a class object, a set object that represents a set of objects, type information that corresponds to the set object and that includes the types of the elements of the object, and also information about the inheritance relationship of the type Management means for managing a class object, and a class object corresponding to the specific object when associating the specific object among the plurality of objects with the aggregate object,
And a type checking means for checking the type based on the class object corresponding to the aggregate object.

[0014]

In the first aspect of the invention, the type checking means makes the first object when relating (substituting) the first object (eg, persistent object) to the attribute of the second object (eg, persistent object). Type checking is performed based on the class object corresponding to the persistent object and the class object corresponding to the second persistent object. As a result of the type check, when the types of the attributes defined in the respective class objects match, the first persistent object is actually assigned to the attribute of the second persistent object. Also, as a result of type inspection,
Defined in a class object that inherits the attribute type defined in the class object corresponding to the first persistent object and the attribute type defined in the class object corresponding to the second persistent object Even if the attribute types match, the first persistent object is actually assigned to the attribute of the second persistent object. Therefore, according to the present invention, it is possible to perform dynamic type checking in consideration of inheritance relationships.

In the second invention, the type checking means, when relating (inserting) a specific object (for example, a persistent object) to the aggregate object, supports the class object corresponding to the persistent object and the aggregate object. Type checking based on the class object As a result of this type check, if the type of the attribute defined in the class object corresponding to the persistent object and the type of the element defined in the class object corresponding to the aggregate object match, the persistent object Is actually inserted into the aggregate object. Also, the attribute type defined in the class object corresponding to the persistent object and the attribute type defined in the class object inheriting the attribute type defined in the class object corresponding to the aggregate object If so, the persistent object is actually inserted into the aggregate object. Therefore, according to the present invention, it is possible to perform dynamic type checking in consideration of inheritance relationships.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an object-oriented database management system (Object Oriented Database M) according to the present invention.
FIG. 3 is a functional block diagram showing an embodiment of anagement Syatem (OODBMS). In the figure, OODB
The MS 10 has a management unit 11 and a pattern inspection unit 12. The management means 11 manages the database file 20 storing the object-oriented database and expands the contents of this file in the main memory 30. On the other hand, the type checking means 12 performs dynamic type checking on the contents of the database file 20 expanded on the main memory 30 in consideration of the inheritance relationship.

In this embodiment, type conversion is prohibited. In addition, in this embodiment, the OODBMS described above is used.
10 is realized by a control unit such as a processor or a central processing unit executing software (program) for executing the function of the system. Of course, it may be realized by firmware or hardware.

FIG. 2 shows a hardware configuration of an apparatus for implementing the system shown in FIG. 1, such as a computer or a workstation. In the figure, the device comprises an external storage device 210 for storing the database file 20, a main memory 220 in which the contents of the database file 20 are expanded, an input device 230,
It has an output device 240 and a processor 250 as the above-mentioned control means for controlling the above-mentioned respective parts and performing a mold inspection process.

Next, the type checking means 12 at the time of substituting the attributes of the first persistent object for the second persistent object 12
The mold inspection process by the method will be described with reference to FIGS. 3 to 5.

Note that FIG. 3 is a flow chart showing the mold inspection processing operation of the mold inspection means 12, and FIGS. 4 and 5 are diagrams showing the processing steps of the mold inspection processing.

First, FIG. 4 shows the state of data in the type check in the value assignment to the attribute of the persistent object. In the example shown in this figure, the type of the persistent object I1 is given by the class object C1 (relationship 1).
The type of the attribute 1 of the persistent object I1 is the class object C2 (relationship 2) means that the class object C
1 is indicated by the “type of attribute 1”. "Inheritance" of the class object C3 means that the class object C3 inherits the class object C2 (relationship 3).
Indicated by. On the other hand, the type of the persistent object I2 is given by the class object C2 '(relationship 4). Here, it is assumed that class object C2 = class object C2 ′.

The persistent objects I1 and I2 and the class objects C1, C2, C3 and C2 'are all stored in the external storage device 210, and the relationships 1, 2 and
3 and 4 are expressed. That is, the data structure shown in FIG. 4 is stored in the external storage device 210 as a database file.

In the assigning operation, the contents of the database file, that is, the persistent objects I1, I2,
The class objects C1, C2, C3, C2 'are loaded from the external storage device 210 onto the main memory 220 and expanded by the processor 250 (management means 11 in terms of software). As a result, on the main memory 220, the above-mentioned persistent objects and class objects and the above relationships 1, 2, 3, 4 are expressed,
It is also possible to confirm each of these relationships.

Under these assumptions, the type check is performed when the operation of substituting the persistent object I2 as the first persistent object for the attribute of the persistent object I1 as the second persistent object is performed. .

That is, the type checking means 12 obtains the class object X from the type information of the persistent object I2 as shown in FIG. 3 (step 301). As a result of this,
Class object C2 'as class object X
Will be obtained.

Next, the type checking means 12 obtains the class object C1 from the type information of the persistent object I1 (step 302), and obtains the class object C2 which is the type of attribute 1 from this class object C1 (step 303).

When the attribute type of each persistent object, that is, the class object is obtained in this way, the type checking means 1
2 is the class object X is the class object C2
It is determined whether or not (that is, whether or not the attribute types are the same) (step 304).

When the class objects are the same in the above step 304 (when the attribute types are the same), the type checking means 12 substitutes the persistent object I2 for the attribute 1 of the persistent object I1 (step 305), and then the processing is performed. To finish.

This will be specifically described. In this example, class object X is class object C2 '.
And there is a relationship of class object C2 ′ = class object C2. Therefore, in step 304 above, it is determined that the class objects are the same,
As a result, the substitution operation is performed.

On the other hand, if the class objects are different in step 304, the type checking means 12 determines whether or not the class object X inherits the type (step 306).

If it is determined in step 306 that the type is inherited, the current class object X
The parent class object of this class object X is obtained based on the inheritance relationship of the new class object X (step 30).
7) Then, the process returns to step 304.

On the other hand, if it is determined in step 306 that the class object X does not inherit any type, an error occurs (step 308).

Here, the processing according to the judgment result of whether or not the class object X inherits the type will be concretely described. Now, it is assumed that the contents shown in FIG. 5 are expanded in the main memory 220. The contents shown in FIG.
In the content shown in FIG. 4, the class object C2 '
Is deleted and the class object C3 'is added. Here, the class object C3 ′ = class object C3.

By the same processing as above, the class object C3 'is obtained as the class object X from the type information of the persistent object I2, and the persistent object I2 is obtained.
A class object C2 is obtained from the type information of 1.
The class objects thus obtained are obviously different. Then, it is checked whether or not the class object C3 'inherits the type. Since the class object C3 'is the same as the class object C3,
It is only necessary to check whether this class object C3 inherits the type.

As described above, since the class object C3 inherits the class object C2 (relationship 3), it can be seen that the parent class object of the class object C3 is the class object C2. Since the class object C3 is the same as the class object C3 ', the current class object X
It can also be seen that the parent class object of the class object C3 'as is the class object C2.

Therefore, it is only necessary to judge whether the class object C2 as the new class object X and the class object C2 obtained in the process of step 303 are the same. In this case, since the class objects are the same, the persistent object I2 is assigned to the attribute 1 of the persistent object I1.

Therefore, in this example, the persistent object I2
If the type of indicates the type of the class object C2 or the class object C3, the assignment is performed normally,
An error will occur for other class objects.

Next, the type checking process by the type checking means 12 when inserting a persistent object as an element into the aggregate object will be described with reference to FIGS. 6 to 8.

FIG. 6 is a flow chart showing the mold inspection processing operation of the mold inspection means 12, and FIGS. 7 and 8 are diagrams showing the process steps of the mold inspection processing.

First, FIG. 7 shows the state of data in the type check in inserting an element into an aggregate object. As shown in this figure, the element types of the aggregate object S1 are given by the class object C2 (relation 7). The fact that the class object C3 inherits the class object C2 (relationship 8) is indicated by "inheritance" of the class object C3. On the other hand, the type of attribute 1 of the persistent object I2 is given by the class object C2 '(relationship 9). Here, class object C2 = class object C2 ′ is defined.

The aggregate object S1, the persistent object I2, and the class objects C2, C3, and C2 'are all stored in the external storage device 210 and represent the above relationships 7, 8, and 9. That is, the data structure shown in FIG. 7 is stored in the external storage device 210 as a database file.

In the insert operation, the contents of the database file, that is, the aggregate object S1, the persistent object I2, the class objects C2, C3, C
2'from the external storage device 210 to the main memory 22 by the processor 250 (the management means 11 in terms of software).
0 is loaded and expanded. As a result, the main memory 22
0, the aggregate object S1, the persistent object I2 and the class object and the above relations 7, 8,
9 is represented and it is possible to confirm these relationships.

Under such a premise, a type check is performed when performing the insert operation of the persistent object I2 into the aggregate object S1.

That is, the type checking means 12 obtains the class object X from the type information of the persistent object I2 as shown in FIG. 6 (step 401). As a result of this,
As the class object X, the class object C2 'which is the type of the attribute 1 is obtained. Next, the type checking means 12 obtains the class object C2 from the type information of the aggregate object S1 (step 402).

The type checking means 12 that has obtained each class object in this way determines whether the class object X is the same as the class object C2 (whether the attribute type and the element type are the same). (Step 403).

If the class objects are the same in step 403 (the attribute type and the element type are the same), the type checking means 12 substitutes the persistent object I2 into the aggregate object S1 (step 404), and then , The process ends.

This will be specifically described. In this example, class object X is class object C2 '.
And there is a relationship of class object C2 ′ = class object C2. Therefore, in step 403 above, it is determined that the class objects are the same,
As a result, the insert operation is performed.

On the other hand, if the class objects are different in step 403, the type checking means 12 determines whether or not the class object X inherits the type (step 405). As a result of this determination, the type is determined. If inherited, the parent class object of this class object X is obtained based on the inheritance relationship of the current class object X, and this parent class object is redefined as a new class object X (step 406). Then, the process returns to step 403.

On the other hand, if the class object X has not inherited anything in step 405, an error occurs (step 407).

Here, the processing according to the judgment result of whether or not the class object X inherits the type will be concretely described. Now, it is assumed that the contents shown in FIG. 8 are expanded in the main memory 220. The contents shown in FIG. 8 are
In the content shown in FIG. 7, the class object C2 'is deleted and the class object C3' is added. Here, the type of the attribute 1 of the persistent object I2 is the class object C3 '(relationship 10).
It is shown. Also here, the class object C
Define 3 ′ = class object C3.

By the same processing as above, the class object C3 'is obtained as the class object X from the type information of the persistent object I2, and the class object C2 is obtained from the type information of the aggregate object S1. The class objects thus obtained are obviously different. Then, it is checked whether or not the class object C3 'inherits the type. Class object C
Since 3'is the same as the class object C3, it suffices to check whether this class object C3 inherits the type. The result of the investigation in this case is the class object C3 ′ as the current class object X, as in the above-mentioned permanent object substitution processing.
It can be seen that the parent class object of is the class object C2.

Therefore, it is only necessary to determine whether the class object C2 as the new class object X and the class object C2 obtained in the process of step 402 are the same. In this case, it is determined that the class objects are the same, and the persistent object I2 is inserted into the aggregate object S1.

Therefore, in this example, the persistent object I2
If the attribute type of indicates the attribute type of the class object C2 or the class object C3, the insertion is normally performed, and an error occurs in the case of other class objects.

As described above, according to the present embodiment, when the first persistent object is assigned to the attribute of the second persistent object, the attribute of the first persistent object is checked by the type checking by the type checking means. A class object representing the type and a class object representing the attribute type of the second persistent object or a class object inheriting the attribute type of this class object,
When it is determined that they represent the same type, the type checking means performs the operation of assigning the first persistent object to the attribute of the second persistent object. It is possible to perform dynamic type checking in consideration of.

Further, according to this embodiment, when a persistent object is inserted into an aggregate object, a class object that represents the attribute type of the persistent object and the type of the elements of the aggregate object are checked by the type checking by the type checking means. When a class object that represents a class object or a class object that inherits the type of an element of this class object represents the same type, the type checking means performs an operation of inserting a persistent object into an aggregate object. Therefore, when inserting an element into a set object, it is possible to perform dynamic type checking considering inheritance relations.

[0057]

As described above, according to the first invention,
When associating the first object with the second object by the type checking means, the class object corresponds to the class object corresponding to the first object and the class object corresponding to the second object or the second object. Since the type check is performed based on the class object that inherits the attribute type of the class object, it is necessary to check the attribute type defined in the class object corresponding to the first and second objects. As a result, it is possible to determine whether the types of the attributes match, and therefore, there is an advantage that a dynamic type check can be performed in consideration of the inheritance relationship when executing the assignment of the object.

According to the second invention, when the type checking means associates a specific object with the aggregate object, the class object corresponding to the specific object and the class object or the aggregate object corresponding to the aggregate object. Since the type check is performed based on the class object that inherits the type of the element of the class object corresponding to, the type of the attribute defined in the specific object and the element defined in the aggregate object By examining the types of, it is possible to determine whether or not the types match, so when inserting the element into the aggregate object,
This has the advantage that dynamic type checking can be performed in consideration of inheritance relationships.

As described above, since the dynamic type check can be performed in consideration of the inheritance relationship, it is possible to prevent erroneous data substitution or insertion.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of an object-oriented database management system according to the present invention.

FIG. 2 is a block diagram showing a hardware configuration of a device for realizing the system of the embodiment shown in FIG.

FIG. 3 is a flowchart showing a type checking processing operation at the time of a substitution operation by the type checking means of the present embodiment.

FIG. 4 is a diagram illustrating a processing process of a type checking process executed at the time of a substitution operation.

FIG. 5 is a diagram illustrating a processing process of a type checking process executed at the time of a substitution operation.

FIG. 6 is a flowchart showing a mold inspection processing operation at the time of an insertion operation by the mold inspection means of the present embodiment.

FIG. 7 is a diagram illustrating a processing process of a type checking process executed at the time of an insert operation.

FIG. 8 is a diagram illustrating a processing process of a type checking process executed at the time of an insert operation.

[Explanation of symbols]

10 ... Object-oriented database management system, 1
1 ... Management means, 12 ... Type checking means, 20 ... Database file, 30 ... Main memory.

Claims (2)

[Claims] 1. Managing a plurality of objects and a class object that corresponds to each of the objects and holds type information including a type of an attribute of the object and can also hold information regarding inheritance relation of the type. Management means and type checking means for performing a type check based on a class object corresponding to each of the first objects when associating the first object with the second object among the plurality of objects. An object-oriented database management system characterized by the following. 2. A plurality of objects, a class object corresponding to each of the objects, capable of holding type information including a type of an attribute of the object, and also capable of holding information about inheritance relation of the type, Management means for managing a set object representing a set and a class object corresponding to the set object, which holds type information including the types of the elements of the object and can also hold information on inheritance relation of the type; A type check that performs a type check based on a class object corresponding to the specific object and a class object corresponding to the aggregate object when associating the specific object among the plurality of objects with the collective object Object-oriented characterized by including means and Database management system.