Object transferring system and method in an object based computer operating system

• US 5,297,283 A
• Filed: 10/16/1992
• Issued: 03/22/1994
• Est. Priority Date: 06/29/1989
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Cutler, David N., Kelly, James W. Jr., Perazzoli, Frank L. Jr.
• Primary Examiner(s): Shaw, Gareth D.
• Assistant Examiner(s): Chavis, John Q.
• Application Number:
  US07/962,397
• Time in Patent Office: 522 Days
• Field of Search: 395/600, 395/650
• US Class Current: 718/104
• CPC Class Codes: G06F 12/1491 in a hierarchical protection system, e.g. privilege levels, memory rings
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 2221/2141 Access rights, e.g. capability lists, access control lists, access tables, access matrices
• CPC Class Codes: G06F 9/4488 Object-oriented
• CPC Class Codes: G06F 9/468 Specific access rights for resources, e.g. using capability register
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

An object based operating system for a multitasking computer system provides objects which represent the architecture or interrelationships of the system'"'"'s resources. Access to certain objects is required in order to use corresponding resources in the system. All objects have a consistent data structure, and a consistent method of defining the operations which apply to each type of object. As a result, it is relatively easy to add new types of system objects to the operating system. The object based operating system supports multiple levels of visibility, allowing objects to be operated on only by processes with the object'"'"'s range of visibility. This allows objects to be made private to a process, shared by all processes within a job, or visible to all processes within the system. An object or an entire set of objects can be moved to a higher visibility level when objects need to be shared. In addition, access to each object is controlled through an access control list which specifies the processes authorized to access the object, and the types of access that are allowed. An object with a restricted access control list can be associated with a "privileged operation", thereby restricting use of the privileged operation to those user processes authorized to access the corresponding object. Waitable objects are used to synchronize the operation of one or more processes with one another or with specified events. The system provides routines for generating new types of waitable objects without modifying the operating system'"'"'s kernel.

Claims

1. A computer system, comprising:

memory means for storing data and data structures;

a multiplicity of objects comprising data structures stored in said memory means, each said object including characteristic denoting means for denoting at least one attribute of said object;

a multiplicity of container means stored in said memory means for referencing sets of said objects, each container means including means for storing a multiplicity of object pointers to locations in said memory means where said set of objects corresponding to said container means are stored;

each said object including means for denoting one of said container means as the container means in which said object resides;

a multiplicity of processes running concurrently on said computer system, each process including means linking said each process to a subset of said multiplicity of container means and means for accessing only objects referencing by those container means linked to said each process;

wherein at least a plurality of said container means are each linked to two or more processes; and

object transfer means, coupled to said memory means and responsive to an object transfer request by any one of said multiplicity of processes, for transferring an object pointer corresponding to a specified object from a first container means to a specified container means;

said object transfer means including;

collision detecting means for determining whether said specified container means stores an object pointer to an object having characteristic denoting means which denotes the same at least one attribute as denoted by the characteristic denoting means of said specified object and thereby determining whether there is a collision between said specified object and an object referenced by said specified container means; and

means, operative when said collision detecting means does not detect a collision, for storing an object pointer corresponding to said specified object in said specified container means and for denoting in said specified object said specified container as the container in which said specified object resides;

further including object identifiers stored in said memory means, corresponding to each said object, for referencing said objects;

each said object including count means for denoting the number of said object identifiers corresponding to said object which exist in said computer system;

said object transfer means including means for transferring an object pointer corresponding to a specified object only when said count means of said specified object denotes a value of one and for blocking transfer of said corresponding object pointer when said count means of said specified object denotes a value greater than one.

2. A computer system as set forth in claim 1,

each said object pointer in said multiplicity of object container means corresponding to one of said object identifiers;

said object transfer means including object pointer deleting means which deletes said object pointer corresponding to said specified object stored in said first container means and deletes said object identifier corresponding to said deleted object pointer.

6. A computer system as set forth in claim 1,

further including object identifiers stored in said memory means, corresponding to each said object, for referencing said objects;

each said object pointer in said multiplicity of object container means corresponding to one of said object identifiers;

each said object identifier including an authenticating value;

each of said objects including an object authenticating value matching the authenticating value in at least one object identifier corresponding to said object; and

further including object identifier translating means, which responds to an object access request by any of said multiplicity of processes by translating a specified object identifier into a pointer to the corresponding object, including

means for locating an object pointer, corresponding to said specified object identifier, in one of said container means, and

means for verifying that the object pointed to by said located object pointer has an object authenticated value matching the authenticating value in said specified object identifier;

whereby authority to access an object is verified via verification of ownership of an object identifier having a valid object authenticating value.

3. A computer system, comprising:

memory means for storing data and data structures;

a multiplicity of objects comprising data structures stored in said memory means, each said object including characteristic denoting means for denoting at least one attribute of said object;

a multiplicity of container means stored in said memory means for referencing sets of said objects, each container means including means for storing a multiplicity of object pointers to locations in said memory means where said set of objects corresponding to said container means are stored;

each said object including means for denoting one of said container means as the container means in which said object resides;

a multiplicity of processes running concurrently on said computer system, each process including means linking said each process to a subset of said multiplicity of container means and means for accessing only objects referencing by those container means linked to said each process;

wherein at least a plurality of said container means are each linked to two or more processes; and

object transfer means, coupled to said memory means and responsive to an object transfer request by any one of said multiplicity of processes, for transferring an object pointer corresponding to a specified object from a first container means to a specified container means;

said object transfer means including;

collision detecting means for determining whether said specified container means stores an object pointer to an object having characteristic denoting means which denotes the same at least one attribute as denoted by the characteristic denoting means of said specified object and thereby determining whether there is a collision between said specified object and an object referenced by said specified container means;

means, operative when said collision detecting means does not detect a collision, for storing an object pointer corresponding to said specified object in said specified container means and for denoting in said specified object said specified container as the container in which said specified object resides;

collision flag means for denoting whether to delete said specified object when said collision detecting means detects a collision; and

means for deleting said specified object when said collision flag means is set and said collision detecting means detects a collision;

said deleting means leaving said specified object resident in said first container means when said collision flag means is not set and said collision detecting means detects a collision.

4. A computer system as set forth in claim 3, said object transfer means including

transfer abort means which aborts an object transfer when said collision flag means is clear and said collision detecting means detects a collision.

5. A computer system as set forth in claim 3,

each said object including transfer flag means for denoting whether said object is transferable;

said object transfer means including means for denying a request for an object transfer when said transfer flag means of said specified object is clear.

7. A computer system comprising:

memory means for storing data and data structures;

a multiplicity of objects comprising data structures stored in said memory means, said multiplicity of objects including a multiplicity of different types of objects;

each said object including type denoting means for denoting the object type of said object;

a multiplicity of container means stored in said memory means for referencing sets of said objects, each container means including means for storing a multiplicity of object pointers to locations in said memory means where said set of objects are stored;

each said container means including name denoting means for denoting a name for each said object referenced by said container means;

a multiplicity of processes running concurrently on said computer system, each process including means linking said each process to a subset of said multiplicity of container means and means for accessing only objects referencing by those container means linked to said each process;

wherein at least a plurality of said container means are each linked to two or more processes; and

object transfer means, coupled to said memory means and responsive to an object transfer request by any one of said multiplicity of processes, for transferring an object pointer corresponding to a specified object from a first container means to a specified container means;

said object transfer means including;

collision detecting means for determining whether said specified container means stores an object pointer to an object denoting an object type and having a name which matches the object type and name of said specified object and thereby determining whether there is a collision between said specified object and an object referenced by said specified container means; and

means for storing an object pointer corresponding to said specified object in said specified container means when said collision detecting means does not detect a collision;

further including object identifiers stored in said memory means, corresponding to each said object, for referencing said objects;

each said object including count means for denoting the number of said object identifiers corresponding to said object which exist in said computer system;

said object transfer means including means for transferring an object pointer corresponding to a specified object only when said count means of said specified object denotes a value of one and for blocking transfer of said corresponding object pointer when said count means of said specified object denotes a value greater than one.

8. A computer system as set forth in claim 7, each said object pointer in said multiplicity of object container means corresponding to one of said object identifiers;

said object transfer means including object pointer deleting means which deletes said object pointer corresponding to said specified object stored in said first container means and deletes said object identifier corresponding to said deleted object pointer.

9. A computer system comprising:

memory means for storing data and data structures;

a multiplicity of objects comprising data structures stored in said memory means, said multiplicity of objects including a multiplicity of different types of objects;

each said object including type denoting means for denoting the object type of said object;

a multiplicity of container means for referencing sets of said objects, each container means including means for storing a multiplicity of object pointers to locations in said memory means where said set of objects are stored;

each said container means including name denoting means for denoting a name for each said object referenced by said container means;

a multiplicity of processes running concurrently on said computer system, each process including means linking said each process to a subset of said multiplicity of container means and means for accessing only objects referencing by those container means linked to said each process;

wherein at least a plurality of said container means are each linked to two or more processes; and

object transfer means, executed by said central processing unit in response to an object transfer request by any one of said multiplicity of processes, which transfers an object pointer corresponding to a specified object from a first container means to a specified container means;

said object transfer means including;

collision detecting means for determining whether said specified container means stores an object pointer to an object denoting an object type and having a name which matches the object type and name of said specified object and thereby determining whether there is a collision between said specified object and an object referenced by said specified container means; and

means for storing an object pointer corresponding to said specified object in said specified container means when said collision detecting means does not detect a collision;

said object transfer means including

collision flag means for denoting whether to delete said specified object when said collision detecting means detects a collision; and

means for deleting said specified object when said collision flag means is set and said collision detecting means detects a collision;

said deleting means leaving said specified object resident in said first container means when said collision flag means is not set and said collision detecting means detects a collision.

10. In a computer system having

memory means for storing data and data structures;

a multiplicity of objects comprising data structures stored in said memory means, each said object including characteristic denoting means for denoting at least one attribute of said object;

a multiplicity of object identifiers, at least one said object identifier corresponding to each said object;

each said object including count means for denoting the number of said object identifiers corresponding to said object which exist in said computer system;

a multiplicity of processes running concurrently on said computer system, each process including means for accessing specified ones of said multiplicity of objects in said memory means; and

object handling means for providing object storage and manipulation capabilities to said multiplicity or processes;

a computer implemented method of storing and manipulating said objects in said computer system, the steps of the method performed by said object handling means comprising;

storing in said memory means a multiplicity of container means for referencing sets of said objects, and storing in each container means a multiplicity of object pointers to locations in said memory means where said set of objects are stored;

each said object including means for denoting one of said container means as the container means in which said object resides;

wherein each process includes means linking said each process to a subset of said multiplicity of container means and means for accessing only objects referenced by those container means linked to said each process;

wherein at least a plurality of said container means are each linked to two or more processes; and

in response to requests by ones of said multiplicity of processes, transferring an object pointer corresponding to a specified object from a first container means to a specified container means;

said transferring step including the steps of;

determining whether said specified container means stores an object pointer to an object having characteristic denoting means which denotes the same at least one attribute as denoted by the characteristic denoting means of said specified object and thereby determining whether there is a collision between said specified object and an object referenced by said specified container means; and

when said determining step does not detect a collision, storing an object pointer corresponding to said specified object in said specified container means and denoting in said specified object said specified container as the container in which said specified object resides;

said transfer step including transferring an object pointer corresponding a specified object only when said count means of said specified object denotes a value of one and blocking transfer of said corresponding object pointer when said count means of said specified object denotes a value greater than one.

11. The method as set forth in claim 10,

each said object pointer in said multiplicity of object container means corresponding to one of said object identifiers;

said transferrign step including the steps of deleting said object pointer corresponding to said specified object stored in said first container means and deleting said object identifier corresponding to said deleted object pointer.

12. In a computer system having

memory means for storing data and data structures;

a multiplicity of objects comprising data structures stored in said memory means, each said object including characteristic denoting means for denoting at least one attribute of said object;

a multiplicity of object identifiers, at least one said object identifier corresponding to each said object;

a multiplicity of processes running concurrently on said computer system, each process including means for accessing specified ones of said multiplicity of objects in said memory means; and

object handling means for providing object storage and manipulation capabilities to said multiplicity or processes;

a computer implemented method of storing and manipulating said objects in said computer system, the steps of the method performed by said object handling means comprising;

storing in said memory means a multiplicity of container means for referencing sets of said objects, and storing in each container means a multiplicity of object pointers to locations in said memory means where said set of objects are stored;

each said object including means for denoting one of said container means as the container means in which said object resides;

wherein each process includes means linking each said process to a subset of said multiplicity of container means and means for accessing only objects referenced by those container means linked to said each process;

wherein at least a plurality of said container means are each linked to two or more processes; and

in response to requests by ones of said multiplicity of processes, transferring an object pointer corresponding to a specified object from a first one of said container means to a specified container means;

said transferring step including the steps of;

determining whether said specified container means stores an object pointer to an object having characteristic denoting means which denotes the same at least one attribute as denoted by the characteristic denoting means of said specified object and thereby determining whether there is a collision between said specified object and an object referenced by said specified container means; and

when said determining step does not detect a collision, storing an object pointer corresponding to said specified object in said specified container means and denoting in said specified object said specified container as the container in which said specified object resides;

said transferring step including the steps of specifying whether to delete said specified object when said collision detecting means detects a collision, deleting said specified object when said specifying step so specifies and said determining step detects a collision, and leaving said specified object resident in said first container means when said specifying step does not so specify and said detecting step detects a collision.

13. The method set forth in claim 12,

said transferring step including the step of aborting said transferring step when said determining step detects a collision and said specifying step specifies that said specified object is not to be deleted when a collision is detected.

14. The method set forth in claim 12,

each said object including transfer flag means for denoting whether said object is transferable;

said transferring step including the step of aborting said transferring step when said transfer flag means of said specified object is clear.

15. In a computer system having

memory means for storing data and data structures;

a multiplicity of objects comprising data structures stored in said memory means, each said object including type denoting means for denoting the object type of said object;

a multiplicity of object identifiers, at least one said object identifier corresponding to each said object;

each said object including count means for denoting the number of said object identifiers corresponding to said object which exist in said computer system;

a multiplicity of processes running concurrently on said computer system, each process including means for accessing specified ones of said multiplicity of objects in said memory means; and

object handling means for providing object storage and manipulation capabilities to said multiplicity or processes;

a computer implemented method of storing and manipulating said objects in said computer system, the steps of the method performed by said object handling means comprising;

storing in said memory means a multiplicity of container means for referencing sets of said objects, and storing in each container means a multiplicity of object pointers to locations in said memory means where said set of objects are stored and a name for each said object referenced by said container means;

wherein each process includes means linking said each process to a subset of said multiplicity of container means and means for accessing only objects referenced by those container means linked to said each process;

wherein at least a plurality of said container means are each linked to two or more processes; and

in response to requests by ones of said multiplicity of processes, transferring an object pointer corresponding to a specified object from a first one of said container means to a specified container means;

said transferring step including the steps of;

determining whether said specified container means stores an object pointer to an object denoting an object type and having a name which matches the object type and name of said specified object and thereby determining whether there is a collision between said specified object and an object referenced by said specified container means; and

when said determining step does not detect a collision, storing an object pointer corresponding to said specified object in said specified container means and denoting the name of siad specified object in said specified container;

said transfer step including transferring a specified object only when said count means of said specified object denotes a value of one and blocking transfer of said corresponding object pointer when said count means of said specified object denotes a value greater than one.