Method and system for tracking software components

• US 6,721,898 B1
• Filed: 05/28/1999
• Issued: 04/13/2004
• Est. Priority Date: 02/03/1999
• Status: Expired due to Term

• Current Assignee: William H. Gates
• Original Assignee: William H. Gates
• Inventors: Hasha, Richard
• Primary Examiner(s): Beausoliel, Robert
• Assistant Examiner(s): Bonzo, Bryce P.
• Application Number:
  US09/322,455
• Time in Patent Office: 1,782 Days
• Field of Search: 714/4, 714/37, 714/38, 714/43, 714/48, 709/318
• US Class Current: 714/4.3
• CPC Class Codes: G06F 11/0715 in a system implementing multitasking multitasking per se G06F9/46
• CPC Class Codes: G06F 11/302 where the computing system component is a software system
• CPC Class Codes: G06F 11/3065 Monitoring arrangements determined by the means or processing involved in reporting the monitored data error or fault reporting or logging G06F11/0766
• CPC Class Codes: G06F 8/38 for implementing user interfaces
• CPC Class Codes: G06F 9/449 Object-oriented method invocation or resolution
• CPC Class Codes: G06F 9/465 Distributed object oriented systems remote method invocation [RMI] G06F9/548
• CPC Class Codes: G06T 1/00 General purpose image data processing
• CPC Class Codes: H04L 12/2803 Home automation networks
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: H05B 47/155 Coordinated control of two or more light sources
• CPC Class Codes: H05B 47/18 via data-bus transmission

Abstract

A method system for tracking the state of an entity (e.g., an object) on behalf of a client (e.g., an application program). The states of an entity include up and down. The tracking system of the present invention receives a request from a client to track the state of an entity. The tracking system then watches the state of the entity to detect when the entity enters the up state. When the entity enters the up state, the tracking system performs a behavior that is specified by the client to be performed when the entity enters the up state. When the entity is in the up state, the tracking system monitors the state of the entity to detect when the entity enters the down state. When the entity enters the down state, the tracking system performs a behavior that is specified by the client to be performed when the entity enters the down state. When the tracking system receives a request from the client for a pointer to the entity, the tracking system determines the current state of the entity and either provides a pointer to the entity or indicates that a pointer is not being provided.

Claims

1. A method in a computer system for tracking a state of an entity for a client, the state of the entity being up or down, the method comprising:

receiving a request from the client to track the state of the entity;

watching the state of the entity to detect when the entity enters the up state;

when entity enters the up state, performing a behavior specified by the client to be performed when the entity enters the up state;

monitoring the state of the entity to detect when the entity enters the down state;

when the entity enters the down state, performing a behavior specified by the client to be performed when the entity enters the down state;

receiving a request from the client for a reference to the entity; and

in response to receiving the request for a reference to the entity,

when the entity is in the up state, providing to the client the reference to the entity; and

when the entity is in the down state, notifying the client that no reference to the entity is being provided.

2. The method of claim 1 including:

receiving a notification that the state of the entity has changed;

retrieving a reference to the entity;

when a reference to the entity was previously retrieved, determining whether the newly retrieved reference corresponds to a different occurrence of the entity and, if so, performing the behavior specified by the client to be performed when the entity enters the down state followed by performing the behavior specified by the client to be performed when the client enters the up state.

3. The method of claim 2 wherein the determining of whether the newly retrieved reference corresponds to a different occurrence of the entity includes checking a time of creation associated with the references.

4. The method of claim 2 wherein the determining of whether the newly retrieved reference corresponds to a different occurrence of the entity includes checking unique occurrence identifiers associated with the references.

5. The method of claim 2 wherein the retrieving of the reference includes providing a name of the entity.

6. The method of claim 2 wherein the entity is an object and the reference is a pointer to the object.

7. A computer system for tracking a state of an entity, the system comprising:

a client component that registers when an entity is to be tracked, that provides a client behavior to be performed when the entity changes state, and that requests a reference to the entity;

an entity tracking component that receives the registration from the client component to track the entity, that when requested by the client component provides a reference to the entity, that requests a reference to the entity, and that provides a tracking behavior to be performed when the entity changes state that effects the performing of the client behavior provided by the client component; and

an entity manager that when the entity changes state performs the tracking behavior provided by the entity tracking component and that when requested by the entity tracking component provides a reference to the entity.

8. A computer system for tracking a state of an entity, the system comprising:

a registration component that receives a registration from a client to track the entity, the registration indicating a behavior to perform when the entity changes state;

a reference component that retrieves a reference from an entity manager when the reference is in an up state and that provides to the client a reference to the entity when requested by the client; and

a notification component that requests to be notified when the entity changes state and that when a notification is received performs the indicated behavior.

9. The computer system of claim 8 wherein the notification component, when a notification is received which indicates that the entity has entered the up state, retrieves a reference to the entity and when a previously retrieved reference and the newly retrieved reference refer to the same occurrence of the entity, suppresses the performing of the indicated behavior.

10. A method in a system for tracking a state of an object in a distributed object environment, the method comprising:

registering to be notified when the state of the object changes; and

when the state of the object changes, receiving a notification, performing a behavior associated with the change in state and receiving a behavioral reference to the object.

11. The method of claim 10 wherein the registering identifies the object using a tracking reference.

12. The method of claim 10 wherein one software components registers to be notified and another software component receives the notification.

13. The method of claim 10 wherein the state change is the object entering the up state.

14. The method of claim 10 wherein the state change is the object entering the down state.

15. A computer readable medium comprising computer executable instructions for performing the method of claim 10.

16. A modulated data signal carrying computer executable instructions for performing the method of claim 10.

17. A computing device comprising means for performing the method of claim 10.

18. A method for tracking at least two states of an object on behalf of a client by a tracking system, comprising:

receiving by the tracking system a request from the client to track the at least two states of the object;

watching the state of the object to detect when the object changes state;

when the object enters the first state, first performing at least one behavior that is specified by the client to be performed when the object enters the first state; and

when the object enters the second state, second performing at least one behavior that is specified by the client to be performed when the object enters the second state.

19. A method as recited in claim 18, wherein the at least two states are mutually exclusive states.

20. A method as recited in claim 18, wherein the object is one of a software object, a firmware object and a hardware object and the object is one of an active object and a passive object.

21. A method according to claim 18, wherein when the object enters the second state because of a failure of at least one computing device, objects that reference the failed object do not fail.

22. A method according to claim 18, wherein when the object enters the second state because of a failure of at least one computing device and subsequently the failed object enters the first state, objects that reference the failed object continue to reference the failed object.

23. A method according to claim 18, further including:

upon receiving by the tracking system a request from the client for a reference to the object, determining the current state of the object; and

one of (1) providing a reference to the object to the client and (2) indicating that a reference is not being provided to the client.

24. A method according to claim 23, wherein the reference allows a client to access the behavior of the object.

25. A method according to claim 23, wherein the reference is a behavioral reference and the behavior is accessed by invoking a function of the object using the behavioral reference.

26. A method according to claim 25, wherein the behavioral reference includes at least one of a pointer reference and a message identification.

27. A method according to claim 18, wherein said at least one behavior of said first and second performing includes notification of the client.

28. A computer readable medium comprising computer executable instructions for performing the method of claim 18.

29. A modulated data signal carrying computer executable instructions for performing the method of claim 18.

30. A computing device comprising means for performing the method of claim 18.

31. In a distributed computing environment, a method for tracking the state of an object on behalf of a client by a tracking system having at least four possible states, comprising:

initially waiting for a client to register an interest in the object;

receiving a request from a client to register an interest in the object; and

upon receiving said request, entering by the tracking system into the state of initializing a reference to the object and initializing a reference to the object for use by the tracking system in communicating with the object, wherein said at least four states include waiting for a client to register an interest in the object, initializing a reference to the object, watching for the object to enter the up state and monitoring the object to enter the down state.

32. A method according to claim 31, wherein during the initializing object reference state, the object tracking system creates at least one referencing data structure for use with tracking the object for the client and for use with determining the current state of the object.

33. A method according to claim 32, wherein said at least one referencing data structure includes at least one pointer to the object.

34. An object tracking system including:

a communications bus;

at least one bus management component;

at least one server node and at least one client node, wherein said at least one server node, said at least one client node and said at least one bus management component are interconnected via said communications bus, and wherein each of said at least one client node includes at least one client resource for requesting access to at least one server resource of said at least one server resource;

wherein the at least one bus management component receives a notification from said at least one server node when a resource of said at least one server node one of (1) comes up and (2) goes down, whereby said at least one bus management component tracks all of the resources as they come up and go down.

35. An object tracking system according to claim 34, wherein said communications bus is one of a physical and logical means for communicating between entities.

36. An object tracking system according to claim 34, wherein watching of a resource is coordinated by the at least one bus management component and the monitoring of a resource is performed on a client-to-server node basis without interaction from the at least one bus management component.

37. An object tracking system according to claim 36, wherein when a client wants to watch a resource so that it knows when the resource is in the up state, the client node notifies the at least one bus management component, identifying the resource using a tracking reference and wherein if the resource is already up, then the at least one bus management component notifies the client node that the resource is up and otherwise, the at least one bus management component notifies the client node when the resource comes up and in response to being notified that the resource is up, the client node notifies the at least one bus management component to stop watching for the resource.

38. An object tracking system according to claim 36, wherein the monitoring of a resource is performed on a peer-to-peer basis such that once a client node is informed that a resource has entered the up state, the client node establishes a connection directly with the server node that contains the resource.

39. An object tracking system according to claim 38, wherein once the connection is established, the client node notifies the server node at a predetermined frequency that the client node is still up and running, and if the client node receives an error when notifying the server node, the client node assumes the server node is down and client node internal state is reset accordingly.

40. An object tracking system according to claim 38, wherein when the resource goes down, the server node notifies the client node that the resource is down.

41. An object tracking system according to claim 36, wherein once the connection is established, the client node notifies the server node at a predetermined frequency that the client node is still up and running, and if the server node does not receive this notification, the server node assumes that the resource of the client node is no longer up and running and server node internal state is reset accordingly.

42. An object tracking system according to claim 34, wherein each of said at least one client node and at least one server node includes a resource tracking system and a resource manager, and wherein a client requests the resource tracking system to provide a pointer to a requested resource and to notify the client when the resource comes up or goes down.

43. An object tracking system according to claim 34, wherein each of said at least one client node and at least one server node includes a resource tracking system and a resource manager, wherein the resource tracking system interacts with the resource manager to watch, monitor, and retrieve a pointer to the resource.

44. An object tracking system according to claim 43, wherein the resource manager further detects when resources on the node corresponding to its location come up and go down and notifies at least one of the at least one bus management component and other nodes having a relationship to the resource.

45. An object tracking system according to claim 34, wherein each of said at least one client node and at least one server node includes a resource tracking system and a resource manager, wherein the resource manager includes a watched resource table, a process/resource list and resource directory.

46. An object tracking system according to claim 34, wherein a server node of said at least one server node is also a client node of said at least one client node.

47. A method of communicating between a client node and a resource manager in a tracking system having a communications bus, at least one bus management component, at least one server node and at least one client node, wherein said at least one server node, said at least one client node and said at least one bus management component are interconnected via said communications bus, and wherein each of said at least one client node includes at least one client resource for requesting access to at least one server resource of said at least one server resource, wherein each of said at least one client node includes a resource tracking system and a resource manager, comprising:

transmitting a message from a client node to a resource manager to request at least one of (1) watching a resource, (2) stopping of watching a resource, (3) monitoring a resource, (4) stopping of monitoring a resource and (5) finding a resource; and

notifying the client by the resource manager that the resource has one of (1) come up or (2) gone down by sending messages to the client.

48. A method of communicating according to claim 47, wherein said transmitting includes one transmitting at least one of (1) transmitting by the client a watch resource message to request the resource manager to start watching for the resource to come up, (2) transmitting by the client a stop watching resource message to the resource manager to indicate that the client no longer wants the resource manager to watch for the resource, (3) transmitting by the client a monitor resource message to request the resource manager to start monitoring the resource that is up to go down, (4) transmitting by the client a stop monitoring resource message to request the resource manager to stop monitoring the resource and (5) transmitting by the client a find resource message to find the location of the requested resource.

49. A method of communicating according to claim 47, wherein the resource manager detects by receiving messages from the at least one bus management component when a resource that is being watched goes up and detects by receiving one of an attach and detach message from the node on which the resource is located when a resource that is being monitored goes down and sends one of a resource is up and a resource is down message, respectively, to the client.

50. A method according to claim 47, wherein a server node of said at least one server node is also a client node of said at least one client node.

51. A resource tracking system including:

a communications bus;

at least one bus management component each including a bus manager object that has a first watched resource table and a first resource directory;

at least one server node and at least one client node including a plurality of clients, wherein said at least one server node, said at least one client node and said at least one bus management component are interconnected via said communications bus, and wherein each of said at least one client nodes includes at least one client resource for requesting access to at least one server resource of said at least one server resource, wherein each of said at least one client nodes includes a resource tracking system and a resource manager, which resource manager includes a second watched resource table, a process/resource list and a second resource directory;

wherein the second watched resource table includes an indication of each resource for which a client located at a client node of the at least one client node has requested to watch along with an indication of the requesting client and wherein the second resource directory includes an identification of each resource that is currently up at the client node.

52. A tracking system according to claim 51, wherein the resource manager of the client node interacts with a bus management component at least one of (1) to notify the bus management component when resources of the client node go up and come down and (2) to request that the bus management component watch for a resource on behalf of the client node.

53. A tracking system according to claim 51, wherein the resource manager of the client node uses the second resource directory at least to re-notify at least one bus management component of the resources that are up in the event that one of (1) from the perspective of the client node, the bus management component goes down and then comes back up (2) another of the at least one bus management components takes control of the communications bus and (3) from the perspective of the client node, the original bus management component becomes available again.

54. A tracking system according to claim 51, wherein the resource manager uses the second watched resource table to re-notify at least one bus management component of the resources watched by the clients of the at least one client node.

55. A tracking system according to claim 54, wherein the client node keeps track of the resources that the client node is watching in the second watched resource table and for a resource that a client wants to watch, the corresponding client node sends a watch resource message to the at least one bus management component if no other client at the client node is watching the same resource.

56. A tracking system according to claim 51, wherein a stop watching resource message is sent to at least one bus management component whenever a request is made on behalf of a client node to stop watching for a resource to come up.

57. A tracking system according to claim 51, wherein the client node sends a find resource message to at least one bus management component when it wants to retrieve a behavioral reference to a resource.

58. A tracking system according to claim 51, wherein when a client comes up, with reference to the first watched resource table, at least one bus management component sends a watched resource is up message to each client node that is watching that resource.

59. A tracking system according to claim 51, wherein the first resource directory contains an identifier of and a behavioral reference to each resource that is currently up and when at least one bus management component receives an attach resource message for a resource, the at least one bus management component updates the first resource directory to indicate that the resource is up and checks the watched resource table to determine whether any client nodes are watching the resource.

60. A tracking system according to claim 59, wherein if there is at least one client node watching the resource according to said determining, the at least one bus management component sends a watched resource is up message to each of said at least one client nodes watching the resource.

61. A tracking system according to claim 51, wherein the first resource directory includes an identifier of and a behavioral reference to each resource that is currently up and when at least one bus management component receives a detach resource message, the at least one bus management component updates the first resource directory to indicate that the resource is down.

62. A tracking system according to claim 61, wherein when the at least one bus management component receives a node is down message, the at least one bus management component detaches all resources that were attached at the client node that is down and stops all the watches from the client node.

63. A tracking system according to claim 51, wherein the process/resource list identifies each resource by the process in which the resource is located, such that when a process goes down, the resource manager uses the process/resource list to notify the at least one bus management component that those resources associated with the process are down.

64. A tracking system according to claim 63, wherein the process is at least one of a process, a sub-process, an eventing entity and a computational entity.

65. A tracking system according to claim 63, wherein the client node sends to the at least one bus management component an attach resource message whenever a resource comes up and a detach resource message whenever a resource goes down, and the client node sends a watch resource message to the at least one bus management component to notify the at least one bus management component to start watching for a resource identified by the watch resource message to come up.

66. A tracking system according to claim 51, wherein a server node of said at least one server node is also a client node of said at least one client node.

67. A method of monitoring a resource by a client node in a tracking system having a communications bus, at least one bus management component, at least one server node and at least one client node, wherein said at least one server node, said at least one client node and said at least one bus management component are interconnected via said communications bus, and wherein each of said at least one client nodes includes at least one client resource for requesting access to at least one server resource of said at least one server resource, wherein each of said at least one client nodes includes a resource manager and a first monitor resource component having a monitor resource table and a client connection table and wherein each of said at least one server nodes includes a second monitor resource component having a watched resource table and a resource directory, comprising:

a first monitor resource component of a client node communicating with a second monitor resource component of a server node on a peer to peer basis to implement node to node monitoring of at least one resource; and

pursuant to said communicating, upon a request from the client node to the server node to begin monitoring a resource, sending by the client node a monitor resource message to the resource manager and upon a request from the client node to the server node to stop monitoring a resource, sending by the client node a stop monitoring resource message to the resource manager.

68. A method according to claim 67, further including:

receiving by the client node a request to monitor a resource from a client on the client node;

in response to said receiving, utilizing a reference to the resource transmitted to the client node by the client to identify the server node at which the resource is located; and

sending a connect client message to the server node if a connection is not already established.

69. A method according to claim 68, wherein the connect client message includes a behavioral reference to an interface of the client node and a client context for the server node from the client'"'"'s perspective.

70. A method according to claim 67, wherein the monitor resource table includes a mapping from resources being monitored to the clients that requested to monitor the resources.

71. A method according to claim 67, wherein the client connection table includes the identification of the server node to which the client nodes is connected along with the client context and the server context for the server and client node implicated by said communicating.

72. A method according to claim 67, wherein the server connection table includes behavioral references to the client nodes to which the server node is connected along with the client context and the server context of said communicating.

73. A method according to claim 67, wherein a server node of said at least one server node is also a client node of said at least one client node.

74. A computer readable medium comprising computer executable instructions for performing the method of claim 67.

75. A modulated data signal carrying computer executable instructions for performing the method of claim 67.

76. A computing device comprising means for performing the method of claim 67.