Compiler for a Declarative Event-Driven Programming Model

• US 20090222789A1
• Filed: 02/29/2008
• Published: 09/03/2009
• Est. Priority Date: 02/29/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Frank, Joachim H., Jamison, Wilfred C.
• Granted Patent: US 8,397,216 B2
• Time in Patent Office: Days
• US Class Current: 717/104
• CPC Class Codes: G06F 11/3624 by performing operations on the source code, e.g. via a compiler
• CPC Class Codes: G06F 8/31 Programming languages or programming paradigms
• CPC Class Codes: G06F 9/4498 Finite state machines

Abstract

A compiler generates code providing an execution sequence, from a declarative event-driven model, for execution by a computer. To assist in debugging the declarative event-driven model, the compiler also generates cross-references that relate steps in the generated code to elements of the declarative source code. The cross-references may be used as input to a debugger, along with the declarative source and the generated code, to assist a user who is stepping through the generated code (for example) in understanding which portion of the declarative source gave rise to the current step in the generated execution sequence.

Claims

1. A method of compiling a declarative event-driven model specification, comprising:

providing the declarative event-driven model specification to a compiler; and

generating, by the compiler from the provided declarative event-driven model specification, an executable file comprising a sequence of execution steps for execution on a computer.

2. The method according to claim 1, further comprising:

generating cross-references that identify, for each of a plurality of elements from the declarative event-driven model specification, at least one of the execution steps in the generated executable file that corresponds to that element from the declarative event-driven model specification.

3. The method according to claim 2, wherein the generated cross-references are usable, in combination with the declarative event-driven model specification and the generated executable file, by a debugger for debugging execution of the declarative event-driven model specification on the computer.

4. The method according to claim 1, wherein the generating also generates cross-references that identify, for each of a plurality of elements from the declarative event-driven model specification, at least one of the execution steps in the generated executable file that corresponds to that element from the declarative event-driven model specification.

5. The method according to claim 2, wherein the generated executable file and the generated cross-references are expressed in markup language syntax.

6. The method according to claim 1, wherein the execution steps comprise at least one of:

an event step for receiving an inbound event;

an assignment step for assigning a value;

a branch step for conditional transfer to a different one of the execution steps;

an emit step for specifying that an outbound event is to be emitted;

a terminate step for specifying that a current execution context is to be terminated; and

a fan-out step for specifying event correlation and enabling a context switch.

7. The method according to claim 1, wherein the generating generates a sequence of assignment steps causing data propagation in accordance with the data dependencies from the declarative event-driven model specification.

8. The method according to claim 1, wherein the declarative event-driven model specification defines an observer object and specifies how to update a state of the observer object based on occurrence of events reporting state changes.

9. The method according to claim 1, wherein the declarative event-driven model specification defines a monitoring context for a monitored entity and specifies how to update a state of the monitoring context based on occurrence of events reporting state changes of the monitored entity.

10. The method according to claim 9, further comprising creating at least one instance of the monitoring context to provide an execution context for executing the compiled program.

11. The method according to claim 10, wherein the executing further comprises receiving an inbound event from the monitored entity and updating at least one of the at least one instances of the monitoring context responsive thereto, each updated instance being selected using syntax specified in one of the execution steps that corresponds to receiving the inbound event.

12. A system for compiling a declarative event-driven model specification, comprising:

a computer comprising a processor; and

instructions executable using the processor to perform functions of;

providing the declarative event-driven model specification to a compiler; and

generating, by the compiler from the provided declarative event-driven model specification, an executable file comprising a sequence of execution steps for execution on a computer.

13. The system according to claim 12, further comprising instructions for:

generating cross-references that identify, for each of a plurality of elements from the declarative event-driven model specification, at least one of the execution steps in the generated executable file that corresponds to that element from the declarative event-driven model specification.

14. The system according to claim 13, wherein the generated cross-references are usable, in combination with the declarative event-driven model specification and the generated executable file, by a debugger for debugging execution of the declarative event-driven model specification on the computer.

15. The system according to claim 12, wherein the generating also generates cross-references that identify, for each of a plurality of elements from the declarative event-driven model specification, at least one of the execution steps in the generated executable file that corresponds to that element from the declarative event-driven model specification.

16. The system according to claim 13, wherein the generated executable file and the generated cross-references are expressed in markup language syntax.

17. The system according to claim 12, wherein the execution steps comprise at least one of:

an event step for receiving an inbound event;

an assignment step for assigning a value;

a branch step for conditional transfer to a different one of the execution steps;

an emit step for specifying that an outbound event is to be emitted;

a terminate step for specifying that a current execution context is to be terminated; and

a fan-out step for specifying event correlation and enabling a context switch.

18. The system according to claim 12, wherein the generating generates a sequence of assignment steps causing data propagation in accordance with the data dependencies from the declarative event-driven model specification.

19. The system according to claim 12, wherein the declarative event-driven model specification defines an observer object and specifies how to update a state of the observer object based on occurrence of events reporting state changes.

20. The system according to claim 12, wherein the declarative event-driven model specification defines a monitoring context for a monitored entity and specifies how to update a state of the monitoring context based on occurrence of events reporting state changes of the monitored entity.

21. A computer program product for compiling a declarative event-driven model specification, the computer program product embodied on at least one computer-usable storage media and comprising computer-usable program code for:

providing the declarative event-driven model specification to a compiler; and

generating, by the compiler from the provided declarative event-driven model specification, an executable file comprising a sequence of linear execution steps for execution on a computer to carry out event processing specified in the declarative event-driven model specification.

22. The computer program product according to claim 21, further comprising computer-usable program code for:

generating cross-references that identify, for each of a plurality of elements from the declarative event-driven model specification, at least one of the execution steps in the generated executable file that corresponds to that element from the declarative event-driven model specification.

23. The computer program product according to claim 22, wherein the generated cross-references are usable, in combination with the declarative event-driven model specification and the generated executable file, by a debugger for debugging execution of the declarative event-driven model specification on the computer.

24. The computer program product according to claim 21, wherein the generating also generates cross-references that identify, for each of a plurality of elements from the declarative event-driven model specification, at least one of the execution steps in the generated executable file that corresponds to that element from the declarative event-driven model specification.

25. The computer program product according to claim 22, wherein the generated executable file and the generated cross-references are expressed in markup language syntax.

26. The computer program product according to claim 21, wherein the execution steps comprise at least one of:

an event step for receiving an inbound event;

an assignment step for assigning a value;

a branch step for conditional transfer to a different one of the execution steps;

an emit step for specifying that an outbound event is to be emitted;

a terminate step for specifying that a current execution context is to be terminated; and

a fan-out step for specifying event correlation and enabling a context switch.

27. The computer program product according to claim 21, wherein the declarative event-driven model specification defines an observer object and specifies how to update a state of the observer object based on occurrence of events reporting state changes.

28. The computer program product according to claim 21, wherein the declarative event-driven model specification defines a monitoring context for a monitored entity and specifies how to update a state of the monitoring context based on occurrence of events reporting state changes of the monitored entity.