System and method for managing control flow of computer programs executing in a computer system

• US 5,754,855 A
• Filed: 05/12/1997
• Issued: 05/19/1998
• Est. Priority Date: 04/21/1994
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Smith, Robert Milton II, Osborn, Timothy William, Wheatley, Michael Thomas, Miller, Stephen Sherman
• Primary Examiner(s): Harrell, Robert B.
• Assistant Examiner(s): Najjar, Saleh
• Application Number:
  US08/854,363
• Time in Patent Office: 372 Days
• Field of Search: 395/671, 395/672, 395/676, 364/281.3, 364/286
• US Class Current: 718/106
• CPC Class Codes: G06F 9/44 Arrangements for executing specific programs
• CPC Class Codes: G06F 9/542 Event management; Broadcasting; Multicasting; Notifications

Abstract

Processing an event signifying a condition in a computer system is described. The computer system maintains an invocation stack which includes a plurality of stack frames. Such event processing operates by selecting a stack frame from the invocation stack, and then determining whether a user specified event processing procedure capable of processing the event has been registered with the selected stack frame. If a user specified event processing procedure has been so registered, then the event is processed using the user specified event processing procedure as specified by a set of rules and options defined for the disposition and/or processing of the specific event. Optionally, it is then determined whether a language specific event processing procedure capable of processing the event has been registered with the selected stack frame. If a language specific event processing procedure has been so registered, then the event is processed using the language specific event processing procedure as specified by a set of rules and options defined for the disposition and/or processing of the specific event. If an user specified event processing procedure capable of processing the event or a language specific event processing procedure capable of processing the event has not been registered with any stack frame of the invocation stack or have chosen not to terminate the event processing, then the event is processed using an applicable default event processing procedure.

Claims

1. A method of dynamically processing an event signifying a condition in a computer system, an invocation stack being maintained in said computer system, said invocation stack comprising a plurality of stack frames, the method comprising the steps of:

(1) selecting a condition event processing manager to process said event based upon an event token representing an event from a routine of the computer system, the event token containing information identifying and otherwise pertaining to the event;

(2) selecting a stack frame from said invocation stack in response to said event, wherein the run-time occurrence of said event is substantially unpredictable;

(3) determining whether a run-time event processing sub-manager associated with said selected condition event processing manager, and including user-defined event processing procedures for said event condition, has been registered with said selected stack frame;

(4) processing said event using said run-time event processing sub-manager if said run-time event processing sub-manager has been so registered;

(5) if a run-time event processing sub-manager for said event condition has not been registered with said selected stack frame, then determining whether a language specific event processing sub-manager associated with said selected condition event processing manager, and including event processing procedures defined by programming procedures for said event condition, has been registered with said selected stack frame; and

(6) processing said event using said language specific event processing sub-manager if said language specific event processing sub-manager has been so registered.

2. The method of claim 1, further comprising the steps of:

(7) if a language specific event processing sub-manager for said event condition has not been registered with said selected stack frame, then selecting another stack frame from said invocation stack; and

(8) repeating steps (3)-(7) until one of condition (i) and condition (ii) occurs;

condition (i);

all stack frames in said invocation stack have been selected; and

condition (ii);

said event has been processed.

3. The method of claim 2, further comprising the step of:

(9) processing said event using a default event processing sub-manager associated with said selected condition event processing manager, and including default procedures for processing said event, if a run-time event processing sub-manager for said event condition and a language specific event processing sub-manager for said event condition have not been registered with any stack frame of said invocation stack.

4. The method of claim 1 in which an execution entity executes in said computer system, said execution entity comprising a plurality of computer language and programming paradigm diverse routines, said invocation stack being used by said execution entity during execution of said execution entity in said computer system, the method also comprising the following steps which are performed prior to step (1):

(a) detecting said event by a routine of said execution entity; and

(b) generating an event token that is intelligible to all routines of said execution entity, said event token containing information identifying and otherwise pertaining to said event;

wherein steps (3)-(6) are performed using said information contained in said event token.

5. The method of claim 4, wherein step (b) comprises the steps of:

generating event identification information identifying a type of said event;

generating event qualifying information specific to said event; and

combining said event identification information and said event qualifying information to thereby generate said event token.

6. An event manager for dynamically processing an event signifying a condition in a computer system, an invocation stack being maintained in said computer system, said invocation stack comprising a plurality of stack frames, an execution entity executing in said computer system, said execution entity comprising a plurality of computer language and programming paradigm diverse routines, said invocation stack being used by said execution entity during execution of said execution entity in said computer system, said event manager comprising:

a plurality of condition event processing managers each for processing events of a particular event type, wherein the run-time occurrence of each of said events is substantially unpredictable; and

a controlling event manager comprising;

means for receiving an event token representing an event from one of the routines of said execution entity, said event token being intelligible to all routines of said execution entity, said event token containing information identifying and otherwise pertaining to said event,

means for referring to said information contained in said event token to identify an event type of said event,

means for selecting one of said event processing managers in accordance with said identified event type as represented by a received event token, and

means for enabling said selected event processing manager to process said event;

wherein said selected condition event processing manager comprises;

a plurality of event processing sub-managers, each said event processing sub-manager specifying procedures for processing said events of a particular event type, said sub-managers including a language specific event processing sub-manager comprising event processing procedures defined by programming procedures and a run-time event processing sub-manager comprising user-defined event processing procedures,

means for selecting a stack frame from said invocation stack,

means for determining whether said run-time event processing sub-manager for said event condition has been registered with said selected stack frame, and

means for processing said event using said run-time event processing sub-manager if said run-time event processing sub-manager has been so registered,

means for determining whether said language specific event processing sub-manager for said event condition has been registered with said selected stack frame if a run-time event processing sub-manager for said event condition has not been registered with said selected stack frame, and

means for processing said event using said language specific event processing sub-manager if said language specific event processing sub-manager has been so registered.

7. The event manager of claim 6, wherein said event processing sub-managers of said selected event processing manager further comprises:

a default event processing sub-manager comprising default procedures for processing an event if a run-time event processing sub-manager for said event condition and a language specific event processing sub-manager for said event condition have not been registered with any stack frame of said invocation stack.

8. The event manager of claim 6, further comprising means for enabling said one of said routines of said execution entity to generate said event token, and to transfer said event token to said controlling event manager.

9. The event manager of claim 6, wherein said event token comprises an event identifier field to store event identification information identifying a type of an event, and a qualifying data pointer field for storing an address of a data block containing event qualifying information specific to an event occurrence.

10. The event manager of claim 6, wherein said plurality of event processing managers comprises:

a control flow event manager to process control flow events;

a synchronous condition event manager to process synchronous condition events;

an asynchronous condition event manager to process asynchronous condition events; and

a termination event manager to process termination events.

11. The event manager of claim 6, further comprising a registration event manager to enable registration of event handling procedures with said stack frames of said invocation stack, said registration event manager comprising:

means for receiving registration event tokens, said registration event tokens being intelligible to all routines of said execution entity, said event tokens containing registration information pertaining to registering run-time event processing sub-managers and language specific event processing sub-managers with stack frames of said invocation stack; and

means for registering run-time event processing sub-managers and language specific event processing sub-managers with stack frames of said invocation stack in accordance with said registration information.

12. An event manager, comprising:

a controlling event manager for receiving tokens representative of events and for controlling dispatching of the tokens for processing, wherein each event token contains information identifying and otherwise pertaining to an event;

a registration event manager for registering event processing activities; and

a plurality of selectable condition event processing managers, each said event processing manager processing a distinct type of event;

wherein at least one of said selectable condition event processing managers comprises a plurality of event processing sub-managers, each said sub-manager comprising procedures for processing said distinct type of event;

wherein a particular selectable condition event processing manager is selected for processing an event based upon a token associated with the event.

13. The event manager of claim 12, wherein said plurality of selectable condition event processing managers comprise:

a control flow event manager to process control flow events;

a synchronous condition event manager to process synchronous condition events;

an asynchronous condition event manager to process asynchronous condition events; and

a termination event manager to process termination events.

14. The event manager of claim 12, wherein one of said event processing sub-managers is a run-time environment sub-manager comprising user-defined event processing procedures.

15. The event manager of claim 12, wherein one of said event processing sub-managers is a language specific event processing sub-manager comprising event processing procedures defined by programming procedures.

16. The event manager of claim 12, wherein one of said event processing sub-managers is a default event processing sub-manager comprising default event processing procedures.

17. A program storage device readable by a computer system, tangibly embodying a program of instructions executable by said computer system to perform method steps for enabling said computer system to process an event signifying a condition in said computer system, an invocation stack being maintained in said computer system, said invocation stack comprising a plurality of stack frames, said method steps comprising:

(1) selecting a condition event processing manager to process said event based upon an event token representing an event from a routine of said computer system, the event token containing information identifying and otherwise pertaining to the event;

(2) selecting a stack frame from said invocation stack in response to said event, wherein the run-time occurrence of said event is substantially unpredictable;

(3) determining whether a run-time event processing sub-manager associated with said selected condition event processing manager, and including user-defined event processing procedures for said event condition, has been registered with said selected stack frame;

(4) processing said event using said run-time event processing sub-manager if said run-time event processing sub-manager has been so registered;

(5) if a run-time event processing sub-manager for said event condition has not been registered with said selected stack frame, then determining whether a language specific event processing sub-manager associated with said selected condition event processing manager, and including event processing procedures, defined by programming procedures, for said event condition, has been registered with said selected stack frame; and

(6) processing said event using said language specific event processing sub-manager if said language specific event processing sub-manager has been so registered.

18. The program storage device of claim 17, further comprising the steps of:

(7) if a language specific event processing sub-manager for said event condition has not been registered with said selected stack frame, then selecting another stack frame from said invocation stack; and

(8) repeating steps (3)-(7) until one of condition (i) and condition (ii) occurs;

condition (i);

all stack frames in said invocation stack have been selected; and

condition (ii);

said event has been processed.

19. The program storage device of claim 18, further comprising the step of:

(9) processing said event using an applicable default event processing sub-manager associated with said selected condition event processing manager, and including default procedures for processing an event, if a run-time event processing sub-manager for said event condition and a language specific event processing sub-manager for said event condition have not been registered with any stack frame of said invocation stack.

20. The program storage device of claim 17 in which an execution entity executes in said computer system, said execution entity comprising a plurality of computer language and programming paradigm diverse routines, said invocation stack being used by said execution entity during execution of said execution entity in said computer system, the method also comprising the following steps which are performed prior to step (1):

(a) detecting said event by a routine of said execution entity; and

(b) generating an event token that is intelligible to all routines of said execution entity, said event token containing information identifying and otherwise pertaining to said event;

wherein steps (3)-(6) are performed using said information contained in said event token.

21. The program storage device of claim 20, wherein step (b) comprises the steps of:

generating event identification information identifying a type of said event;

generating event qualifying information specific to said event; and

combining said event identification information and said event qualifying information to thereby generate said event token.

22. A computer program product for use with an invocation stack, the invocation stack comprising a plurality of stack frames, said computer program product comprising:

a computer usable medium having a computer readable program code means embodied in said medium for enabling a computer to process an event signifying a condition in said computer, said computer readable program code means comprising;

computer readable first program code means for enabling said computer to select a condition event processing manager to process said event based upon an event token representing an event from a routine of said computer, the event token containing information identifying and otherwise pertaining to the event;

computer readable second program code means for enabling said computer to select a stack frame from said invocation stack in response to said event wherein the run-time occurrence of said event is substantially unpredictable;

computer readable third program code means for enabling said computer to determine whether a run-time event processing sub-manager associated with said selected condition event processing manager, and including user-defined event processing procedures for said event condition, has been registered with said selected stack frame;

computer readable fourth program code means for enabling said computer to process said event using said run-time event processing sub-manager if said run-time event processing procedure has been so registered;

computer readable fifth program code means for enabling said computer to determine whether a language specific event processing sub-manager associated with said selected condition event processing manager, and including event processing procedures, defined by programming procedures, for said event condition, has been registered with said selected stack frame when a run-time event processing sub-manager for said event condition has not been registered with said selected stack frame; and

computer readable sixth program code means for enabling said computer to process said event using said language specific event processing sub-manager if said language specific event processing sub-manager has been so registered.

23. The computer program product of claim 22, further comprising:

computer readable seventh program code means for enabling said computer to process said event using an applicable default event processing sub-manager associated with said selected condition event processing manager, and including default procedures for processing said event, if a run-time event processing sub-manager for said event condition and a language specific event processing sub-manager for said event condition have not been registered with any stack frame of said invocation stack.

24. The computer program product of claim 23, wherein an execution entity executes in said computer, said execution entity comprising a plurality of computer language and programming paradigm diverse routines, said invocation stack being used by said execution entity during execution of said execution entity in said computer, the computer program product also comprising:

computer readable eighth program code means for enabling said computer to enable a routine of said execution entity to detect said event; and

computer readable ninth program code means for enabling said computer to generate an event token that is intelligible to all routines of said execution entity, said event token containing information identifying and otherwise pertaining to said event;

wherein said computer readable third program code means, said computer readable fourth program code means, said computer readable fifth program code means, and said computer readable sixth program code means operate using said information contained in said event token.

25. The computer program product of claim 24, wherein said computer readable ninth program code means comprises:

computer readable tenth program code means for enabling said computer to generate event identification information identifying a type of said event;

computer readable eleventh program code means for enabling said computer to generate event qualifying information specific to said event; and

computer readable twelfth program code means for enabling said computer to combine said event identification information and said event qualifying information to thereby generate said event token.