Method and system for modeling a legacy computer system

Abstract

A method and system for modifying program applications of a legacy computer system to directly output data in XML format models the legacy computer system, maps the model to an XML schema and automatically modifies one or more applications to directly output XML formatted data in cooperation with a writer engine and a context table. A modeling engine lists the incidents within the applications that write data and generates a report data model. The report data model includes statically determined value or type of the data fields and is written in a formal grammar that describes how the write operations are combined. A modification specification is created to define modifications to the legacy computer system applications that relate applications that write data to the XML schema. A code generation engine then applies the modification specification to the applications to write modified applications that, in cooperation with a writer engine and context table, directly output XML formatted data from the legacy computer system without a need for transforming the data.

Claims

We claim:

1. A computer-implemented method for modeling a legacy computer system comprising:

identifying incidents of applications of the legacy computer system that output data;

creating a control flow graph of the output incidents;

wherein the incidents comprise report commands; and

wherein the control flow graph comprises plural nodes having associated arcs, at least some of the plural nodes associated with an output incident.

2. The method of claim 1 further comprising:

identifying the value or type of the data fields associated with each output incident; and

attaching the value or type to the control flow graph.

3. The method of claim 2 wherein identifying the value or type further comprises:

identifying output incidents of invariant data fields; and

attaching the value of each invariant data field to its associated control flow graph incident.

4. The method of claim 2 wherein identifying the value or type further comprises:

identifying output incidents of variant data fields; and

attaching the type of each variant data field to its associated control flow graph incident.

5. A computer-implemented method for modeling a legacy computer system comprising:

identifying incidents of applications of the legacy computer system that output data;

creating a control flow graph of the output incidents; and

wherein the control flow graph comprises plural nodes having associated arcs, each node associated with an output incident.

6. The method of claim 5 wherein a complete control flow graph of the application (N,A) is used to compute a directed graph (NR, AR) wherein:

n comprises a node in NR if n, an element of N, starts an output process, stops an output process or outputs data; and

<n1, nm> comprises an arc in AR if n1 and nm are in NR and a sequence of arcs <n1, n2>, <n2, n3>, . . . , <nm-1, nm> is in A such that for i from 2 to m-1, ni is not in NR.

7. The method of claim 6 further comprising:

defining the control flow graph as a formal grammar that describes the flow paths from each start command to the associated stop commands.

8. A system for modeling an output application of a legacy computer system comprising:

a modeling engine interfaced with the legacy computer system, the modeling engine operable to analyze an application loaded on the legacy computer system to identify incidents within the application that output data from the legacy computer system;

a control flow graph of the output incidents within the application;

wherein the incidents comprise report commands; and

wherein the control flow graph comprises plural nodes having associated arcs, at least some of the plural nodes associated with an output incident.

9. The system of claim 8, wherein the modeling engine is operable to identify the incidents within the source code of the application.

10. The method of claim 5, further comprising:

identifying the value or type of the data fields associated with each output incident; and

attaching the value or type to the control flow graph.

11. The method of claim 10, wherein identifying the value or type further comprises:

identifying output incidents of invariant data fields; and

attaching the value of each invariant data field to its associated control flow graph incident.

12. The method of claim 10, wherein identifying the value or type further comprises:

identifying output incidents of variant data fields; and

attaching the type of each variant data field to its associated control flow graph incident.

13. The method of claim 5, further comprising

associating the incidents with an Extensible Markup Language schema; and

creating a specification to modify the legacy computer system applications to provide output in Extensible Markup Language format.

14. The method of claim 13, further comprising automatically modifying the legacy computer system applications in accordance with the specification.

15. A computer-implemented method for modeling a legacy computer system comprising:

identifying incidents of applications of the legacy computer system that output data;

creating a control flow graph of the output incidents;

associating the incidents with an Extensible Markup Language schema; and

creating a specification to modify the legacy computer system applications to provide output in Extensible Markup Language format.

16. The method of claim 15 further comprising:

automatically modifying the legacy computer system applications in accordance with the specification.

17. A system for modeling an output application of a legacy computer system comprising:

a modeling engine interfaced with the legacy computer system, the modeling engine operable to analyze an application loaded on the legacy computer system to identify incidents within the application that output data from the legacy computer system;

a control flow graph of the output incidents within the applications;

wherein the control flow graph comprises plural nodes, each node associated with an output incident;

wherein a complete control flow graph of the application (N,A) is used to compute a directed graph (NR, AR) wherein:

n comprises a node in NR if n, an element of N, starts an output process, stops an output process or outputs data; and

<n1, nm> comprises an arc in AR if n1 and nm are in NR and a sequence of arcs <n1, n2>, <n2, n3>, . . . , <nm-1, nm> is in A such that for i from 2 to m-1, ni is not in NR.

18. A system for modeling an output application of a legacy computer system comprising:

a modeling engine interfaced with the legacy computer system, the modeling engine operable to analyze an application loaded on the legacy computer system to identify incidents within the application that output data from the legacy computer system;

a control flow graph of the output incidents within the application;

wherein the incidents comprise report commands; and

wherein the control flow graph of the output incidents comprises a formal grammar that describes the flow paths from each start command to the associated stop commands.

19. A system for modeling an output application of a legacy computer system comprising:

a modeling engine interfaced with the legacy computer system, the modeling engine operable to analyze an application loaded on the legacy computer system to identify incidents within the application that output data from the legacy computer system;

a control flow graph of the output incidents within the application;

wherein the incidents comprise report commands; and

a graphical user interface in communication with the modeling engine, the graphical user interface operable to display the control flow graph formal grammar and the incidents.

20. The system of claim 19 wherein the graphical user interface further communicates with a mapping engine and an Extensible Markup Language schema, the mapping engine operable to map the incidents of the applications with the control flow graph formal grammar and the Extensible Markup Language schema.

21. A computer-implemented method for modeling a legacy computer system comprising:

creating a control flow graph of output incidents of applications of a legacy computer system;

wherein the control flow graph comprises plural nodes having associated arcs, each node associated with an output incident; and

wherein a complete control flow graph of the application (N,A) is used to compute a directed graph (NR, AR) wherein:

n comprises a node in NR if n, an element of N, starts an output process, stops an output process or outputs data; and

<n1, nm> comprises an arc in AR if n1 and nm are in NR and a sequence of arcs <n1, n2>, <n2, n3>, . . . , <nm-1, nm> is in A such that for i from 2 to m-1, ni is not in NR.

22. A computer-implemented method for modeling a legacy computer system comprising:

identifying incidents of applications of the legacy computer system that output data;

creating a control flow graph of the output incidents;

wherein the incidents comprise report commands; and

wherein identifying incidents of applications of the legacy computer system comprises identifying incidents of applications of the legacy computer system within the source code of the applications.

Description

TECHNICAL FIELD

This invention relates in general to the field of computer systems, and more particularly a method and system for reporting XML data from a computer system.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

FIG. 1 depicts a block diagram of a code generation system in communication with a legacy computer system;

FIG. 2 depicts a flow diagram of the generation of modified legacy program applications to output XML data;

FIG. 3 depicts a flow diagram of the generation of a model of the write operations of a legacy program application;

FIG. 4 depicts a sample output of a legacy computer system report for a telephone bill;

FIG. 5 depicts XML formatted data corresponding to the legacy computer system report depicted by FIG. 4;

FIG. 5A depicts an XML schema for the output depicted in FIG. 5;

FIG. 6 depicts a graphical user interface for mapping legacy computer system code to an Extensible Markup Language schema and report data model;

FIG. 6A depicts underlying COBOL code modeled by the report data model of FIG. 6;

FIG. 7 depicts a sample Extensible Markup Language schema for outputting address data;

FIG. 7A depicts a tree structure for the schema of FIG. 7;

FIG. 7B depicts a computed data context table for the schema depicted by FIG. 7; and

FIG. 8 depicts a flow diagram of an XML print operation that ensures generation of syntactically correct Extensible Markup Language data output.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention are illustrated in the figures, like numeral being used to refer to like and corresponding parts of the various drawings.

In order to take advantage of the opportunities provided by the use of XML as a medium for e-commerce, businesses will eventually have to either replace existing legacy computer systems or re-write the applications on the legacy computer systems. However, businesses have substantial investments in their existing legacy computer systems and related applications so that wholesale replacement of these systems and applications is not practical in the short term. Legacy computer systems perform essential functions such as billing, inventory control, and scheduling that need massive on-line and batch transaction processing. Legacy computer system applications written in languages such as COBOL remain a vital part of the enterprise applications of many large organizations for the foreseeable future. In fact, this installed base of existing software represents the principal embodiment of many organizations' business rules. Although, in principle, these applications could be hand-modified to output data in XML format, in reality the underlying logic of even a simple report application can be difficult to understand and decipher.

Therefore, a tremendous challenge facing many businesses is the rapid and inexpensive adaptation of existing computer systems to take advantage of the opportunities presented by electronic commerce. Even when installing new and updated computer systems, the ever-evolving nature of electronic commerce demands that businesses incorporate flexibility as a key component for new computer systems. XML has become a popular choice for reporting data due to the ease with which XML adapts to essential e-commerce functions, such as transmission over the Internet, direct transfer as an object between different applications and display and manipulation via browser technology. XML's flexibility results from its inclusion of named tags bracketing data that identify the data's relationship within an XML schema. However, implementation of XML data reports relies on accurate use of tags to define the output data within the XML schema. Thus, computer systems that implement XML adhere to the XML schema and use exact bookkeeping to obtain accurate reports.

The present invention aids in the implementation of XML for reports, both by the modification of legacy computer system program applications to output XML data and by the tracking of XML output within an XML schema to ensure an accurate output, whether or not the XML data originates with a legacy computer system. Referring now to FIG. 1, a block diagram depicts a computer system 10 that modifies a legacy computer system 12 to output data in XML format. A code generation system 14 interfaces with legacy computer system 12 to allow the analysis of one or more legacy program applications 16 and the generation of one or more modified legacy program applications 18. Code generation system 14 also provides a writer engine 20 and context table 22 to legacy computer system 12. Legacy computer system 12 is then able to directly output XML formatted data when modified legacy program applications 18 call writer engine 20 in cooperation with context table 22 to output syntactically correct XML data.

Code generation system 14 includes a code generation engine 24, a mapping engine 26 and a modeling engine 28. Modeling engine 28 interfaces with legacy computer system 12 to obtain a copy of legacy program applications 16 for automated review and modeling. Modeling engine 28 generates a list of incidents for points in the program at which data is written. For instance, modeling engine 28 may search the source code of the legacy program applications for reporting or writing commands for selected output streams. The list of report incidents are used to model the report functions of the legacy computer system such as by a report data model that lists the values and types of written data fields from the legacy program applications 16. The list of report incidents is then augmented by a formal grammar that is used to relate the XML schema to the output reported by the legacy program applications. The list of report incidents and the formal grammar are two components of the report data model for the legacy system application program. Intuitively, an incident describes a line in a report, and the formal grammar describes how the application program sequences those lines to form a report.

Modeling engine 28 provides the report data model identifying report incidents in the legacy program applications 16 to mapping engine 26 and modeling/mapping graphical user interface 30. Mapping engine 26 maps the report incidents from the report data model to the XML schema 32 and this relationship between the report data model and XML schema 32 is displayed on modeling/mapping graphical user interface 30. By establishing the relationship between the report incidents of legacy program application 16 and the XML schema 32, mapping engine 26 defines a specification for modification of the legacy program applications 16 to output XML data. Modeling/mapping graphical user interface 30 provides information to programmers of the modification specification. Modeling/mapping graphical user interface 30 produces a modification specification and a context table 22. Optionally, the modeling/mapping graphical user interface 30 allows programmers to create or modify an XML schema.

Code generation engine 24 accepts the modification specification, a copy of the legacy program applications 16, and context table 22 to generate modified legacy program applications 18. Based on the modification specification, code generation engine 24 generates source code in the computer language of the legacy computer system that is inserted in legacy program applications 16 to command output of XML data and saves the modified source code as modified legacy program applications 18. The modified legacy program applications 18 may continue to maintain the legacy computer system report instructions so that the modified program applications 18 continue to report data in the legacy computer system format in addition to the XML format. The outputting of both formats aids in quality control by allowing a direct comparison of data from modified and unmodified code. Alternatively, the modified instructions provided by code generation engine 24 may replace report instructions of legacy program applications 16 so that modified legacy program applications 18 report data exclusively in XML format. Writer engine 20 is written in a computer language of legacy computer system 12 and references context table 22 to determine the appropriate XML schema elements for output of data from legacy system 12. The modified code in modified legacy program applications 18 calls writer engine 20 when outputting data in XML format.

Referring now to FIG. 2, a simplified flow diagram depicts the process of generation of modified legacy program applications that output data in XML format. The process begins at step 34 in which the legacy code of the legacy program applications 16 is made available to code generation system 14. For example, a mainframe legacy computer system running COBOL source code downloads a copy of the source code to code generation system 14 for analysis and generation of modified code.

At step 36, code generation system 14 models the legacy program applications to provide a report data model of the write incidents and their underlying grammar from the legacy program applications' code. For instance, a report data model identifies the incidents within the code of legacy program applications 16 at which data to selected output devices are written, including the values and types of the data. At step 38, the report data model is used to generate a modification specification. The modification specification is generated in conjunction with an XML schema provided at step 40 that defines the data structure for write instructions of the modified legacy program applications 18 to output XML data.

At step 42, the modification specification is used to automatically generate modified legacy code to be run on the legacy computer system 12. The modified legacy code is run at step 44 so that the modified legacy program applications emit output from legacy system 12 in XML format without requiring further transformation of the output data.

The process of modeling legacy computer system 12 is shown in greater detail by reference to FIG. 3. Modeling engine 28 extracts a report data model of legacy program applications 16 through an automated analysis of the underlying legacy code. The automated analysis provides improved understanding of the operation of the legacy code and reduces the likelihood of errors regarding the operation and maintenance of the underlying legacy code. Essentially, modeling engine 28 parses the legacy software process into rules to graph its control flow. An abstraction of the control flow produces a report data model that allows understanding of data types and invariant data values written at each write instruction in the report data model. The report data model, when combined with the values and typing of written data fields, provides a model of legacy program applications 16.

Referring to FIG. 3, the modeling process starts at step 46 through a determination of the legacy programs' control flow graph. The control flow graph of a particular legacy program application is a directed graph (N, A) in which N contains a node for each execution point of the program application and A contains an arc <n₁, n₂>, where n₁ and n₂ are elements of N, if the legacy program application is able to move immediately from n₁ to n₂ for some possible execution state.

At step 48, the write operations of the control flow graph are determined to obtain a data file control graph. Essentially, the control flow graph is abstracted to contain only start nodes, stop nodes, and nodes writing to selected data files. This results in a data file control graph that identifies the write incidents in the legacy program applications. The data file control graph abstracted from a control flow graph (N, A) is a directed graph (N_R, A_R) A node n is in the set of nodes N_R if the node n starts a legacy program application, stops a legacy program application or writes to a data file. The arc <n₁, n_m> is in A_R if both n₁ and n_m are in the set of nodes N_R and a sequence of arcs <n₁, n₂>, <n₂, n₃>, . . . <n_m-1, n_m> exists in A where, for i from 2 to m-1, n_i is not in the set of nodes N_R.

Once the data file control graph is completed, at step 50, information about the data written at each data file write node is attached to the data file control graph. For instance, the values or the type of each data field written by each node are statically determined via data flow in the control flow graph and are attached to the nodes of the data file control graph.

At step 52, the paths from the start nodes through the data file control graph to the stop nodes are represented in a formal grammar. This formal grammar with the attached data field information form the report data model. This model is an abstract representation of the data files that can be written by the legacy program applications and provides the basis on which a modification specification can be written.

The report data model is presented in two parts. First, each write node with its attached data field information is presented as an incident. These incidents are the most basic or leaf sub-expressions of the report data model. Second, the non-leaf sub-expressions of the report data model are presented as rules hierarchically building up from the incidents.

The generation and presentation of a report data model of legacy program applications may be illustrated by consideration of a telephone bill example. FIG. 4 depicts the printed output from a COBOL program for a telephone bill. A typical COBOL program prints the telephone bill in a predetermined format that may include, for example, predetermined paper sizes and column dimensions. The printing of the "TOTAL CALLS" line in FIG. 4 is the result of a computation of the total number of calls, total time of the calls and the total cost of the calls. As an example of a single node of a control flow graph, the incident derived from COBOL code for outputting the total calls line of FIG. 4 is as follows:

• Inventors
  Ballantyne, Alando M.; Smith, Michael K.; Hines, Larry M.;
• Assignee
  Electronic Data Systems Corporation (Plano, TX)
• Published
  Jan-31-2006
• Current US Classes:
  707/501.1
  707/513
  717/107
  717/108
  717/109
  717/115
  717/121
  717/122
• Application #
  522319
• International Classes
  G06F 9/44     (20060101)
• Field of Search
  703/22 709/223 717/5 717/100-122 717/131-133 717/136 707/101 707/501.1 707/513 345/760
• Examiner
  Dam; Tuan
• Agent
  Lineberry; Allen Scott
• US Patent References:
  5640550
  5857194
  5960200
  6125391
  6182024
  6209124
  6230117
  6347307
  6418446
  6446110
  6502236
  6519617
  6523042
  6550054
  6604100
  6609108
  6618852
  6687873