Processing of Expressions

• US 20080196016A1
• Filed: 02/13/2008
• Published: 08/14/2008
• Est. Priority Date: 02/13/2007
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Todd, Stephen James
• Granted Patent: US 8,161,468 B2
• Time in Patent Office: Days
• US Class Current: 717/143
• CPC Class Codes: G06F 2209/547 Messaging middleware
• CPC Class Codes: G06F 9/546 Message passing systems or structures, e.g. queues

Abstract

In many messaging systems, message selection filtering involves a significant processing overhead. This includes the parsing and preparing of the message selection filters in readiness for evaluation, as well as the evaluation itself. In systems which involve parsing and prepare processing for expressions that include repeated patterns (such as in many JMS environments), a template-based shortcutting of the conventional processing improves performance. A stored parsing template is used to parse an input sequence such as a received data processing instruction. The parse is used to identify expressions of a first type that can then be implicitly optimized by using a stored evaluation template that is associated with expressions of that type.

Claims

1. A method for processing of expressions in a data processing system, comprising the steps of:

parsing a data processing instruction using a parsing template, which parsing template defines elements of a first type of expression that can be evaluated to control a conditional data processing operation, to identify elements of an expression of said first type including expression parameter values;

selecting an evaluation template representing said first type of expression in a form that is optimized for evaluation;

inserting parameter values identified by the parsing step into the evaluation template to generate optimized evaluation code; and

using the optimized evaluation code to evaluate said expression.

2. The method of claim 1, wherein the parsing step comprises a first parsing process that compares a data processing instruction with a parsing template tree, in which elements of a set of parsing templates are each associated with a node of the tree, and parses the data processing instruction using a matching parsing template if the parsing template tree includes a matching parsing template.

3. The method of claim 2, wherein, if the parsing template tree does not include a matching parsing template:

using a second parsing process to parse the data processing instruction to identify elements of an expression;

performing a prepare process on the expression elements to generate optimized evaluation code,

deriving a parsing template from the result of parsing by the second parsing process;

deriving an evaluation template from the result of processing by the prepare process; and

saving the derived parsing template and the derived evaluation template.

4. The method of claim 3, wherein saving the derived parsing template comprises saving the derived parsing template in association with a leaf node of the parsing template tree, and wherein saving the derived evaluation template comprises associating the derived evaluation template with said leaf node.

5. The method of claim 4, wherein selecting an evaluation template representing said first type of expression in a form that is optimized for evaluation further comprises selecting an evaluation template that is associated with a leaf node of the parsing template tree.

6. The method of claim 5, wherein said expression is a message selection filter expression.

7. The method of claim 5, wherein said expression is a message transformation expression.

8. A data processing apparatus comprising:

a data processing unit;

a data storage unit for storing a set of templates;

a template-based parser for controlling the data processing unit to parse an input data processing instruction, using a stored parsing template that defines elements of a first type of expression that can be evaluated to control a conditional data processing operation, to identify elements of an expression of said first type including expression parameter values;

an evaluation template selector associated with said template-based parser for selecting a stored evaluation template that represents said first type of expression in a form that is optimized for evaluation;

a code generator for inserting parameter values identified by the parsing step into the evaluation template to generate optimized evaluation code;

a receiver for receiving a data communication; and

an evaluator for evaluating the expression, using the optimized evaluation code, to control performance of a conditional data processing operation in relation to the received data communication.

9. The data processing apparatus of claim 8, further comprising:

a second parser for performing a second parsing process, responsive to a comparison of the expression with a parsing template tree determining that the tree does not include a matching parsing template, to parse the data processing instruction to identify elements of an expression; and

prepare process logic for performing a prepare process for generating optimized evaluation code for the expression.

10. The data processing apparatus of claim 9, further comprising:

an expression template generator for deriving a parsing template from the result of parsing by the second parsing process;

an evaluation template generator for deriving an evaluation template from the result of processing by the prepare process; and

storage control logic for saving the derived parsing template and the derived evaluation template in the data storage means.

11. The data processing apparatus of claim 10, wherein the storage control logic for saving comprises first logic for saving the derived parsing template in association with a leaf node of the parsing template tree and second logic for saving the derived evaluation template in association with the same leaf node.

12. A computer program product for performing processing of expressions in a data processing system, said computer program product comprising a computer usable medium having computer usable program code embodied therewith, said computer usable program code comprising:

computer usable program code configured to parse a data processing instruction using a parsing template, which parsing template defines elements of a first type of expression that can be evaluated to control a conditional data processing operation, to identify elements of an expression of said first type including expression parameter values;

computer usable program code configured to select an evaluation template representing said first type of expression in a form that is optimized for evaluation;

computer usable program code configured to insert parameter values identified by the parsing step into the evaluation template to generate optimized evaluation code; and

computer usable program code configured to use the optimized evaluation code to evaluate said expression.

13. The computer program product of claim 12 wherein the computer usable program code configured to parse a data processing instruction using a parsing template further comprises computer usable program code configured to perform a first parsing process that compares a data processing instruction with a parsing template tree, in which elements of a set of parsing templates are each associated with a node of the tree, and computer usable program code configured to parse the data processing instruction using a matching parsing template if the parsing template tree includes a matching parsing template.

14. The computer program product of claim 13 further comprising computer usable program code configured, if the parsing template tree does not include a matching parsing template to:

use a second parsing process to parse the data processing instruction to identify elements of an expression;

perform a prepare process on the expression elements to generate optimized evaluation code,

derive a parsing template from the result of parsing by the second parsing process;

derive an evaluation template from the result of processing by the prepare process; and

save the derived parsing template and the derived evaluation template.

15. The computer program product of claim 14 wherein the computer usable program code configured to save the derived parsing template further comprises computer usable program code configured to save the derived parsing template in association with a leaf node of the parsing template tree, and wherein the computer usable program code configured to save the derived evaluation template further comprises computer usable program code configured to associate the derived evaluation template with said leaf node.

16. The computer program product of claim 15 wherein said computer usable program code configured to select an evaluation template representing said first type of expression in a form that is optimized for evaluation further comprises computer usable program code configured to select an evaluation template that is associated with a leaf node of the parsing template tree.

17. The computer program product of claim 16 wherein said expression is a message selection filter expression.

18. The computer program product of claim 16 wherein said expression is a message transform expression.