MainframeMaster

COBOL Tutorial

COBOL XML-SCHEMA - Quick Reference

Progress0 of 0 lessons

Overview

XML-SCHEMA in COBOL refers to XML schema validation capabilities that allow COBOL programs to validate XML documents against predefined schema definitions. This ensures that XML documents conform to expected structures, data types, and constraints, providing data integrity and structure compliance in XML processing scenarios.

Key Features

  • Structure validation - Validates element hierarchy and relationships
  • Data type validation - Ensures data conforms to expected types
  • Constraint validation - Enforces business rules and constraints
  • Error reporting - Provides detailed validation error information

Syntax and Usage

XML-SCHEMA usage patterns for validating XML documents against schemas.

Basic XML-SCHEMA Validation

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
       IDENTIFICATION DIVISION.
       PROGRAM-ID. XML-SCHEMA-VALIDATION.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  XML-DOCUMENT    PIC X(1000) VALUE
           "
           John Doe
           12345
           john@example.com
           ".
       01  XML-SCHEMA-FILE PIC X(100) VALUE "customer.xsd".
       01  VALIDATION-STATUS PIC X(20).
       01  ERROR-MESSAGE    PIC X(200).
       
       PROCEDURE DIVISION.
           XML PARSE XML-DOCUMENT
               VALIDATING XML-SCHEMA-FILE
               ON EXCEPTION
                   MOVE "VALIDATION-FAILED" TO VALIDATION-STATUS
                   MOVE XML-ERROR-MESSAGE TO ERROR-MESSAGE
                   DISPLAY "Validation failed: " ERROR-MESSAGE
               NOT ON EXCEPTION
                   MOVE "VALIDATION-SUCCESS" TO VALIDATION-STATUS
                   DISPLAY "XML document is valid"
           END-XML
           
           DISPLAY "Validation status: " VALIDATION-STATUS
           STOP RUN.

Basic XML-SCHEMA validation against a schema file.

Schema Validation with Error Handling

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
       IDENTIFICATION DIVISION.
       PROGRAM-ID. XML-SCHEMA-ERROR-HANDLING.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  XML-DOCUMENT    PIC X(1000) VALUE
           "
           
           John Doe
           12345
           
           
           
           Widget
           5
           29.99
           
           
           ".
       01  XML-SCHEMA-FILE PIC X(100) VALUE "order.xsd".
       01  VALIDATION-STATUS PIC X(20).
       01  ERROR-DETAILS.
           05  ERROR-LINE     PIC 9(4).
           05  ERROR-COLUMN   PIC 9(4).
           05  ERROR-MESSAGE  PIC X(200).
       
       PROCEDURE DIVISION.
           XML PARSE XML-DOCUMENT
               VALIDATING XML-SCHEMA-FILE
               ON EXCEPTION
                   MOVE "VALIDATION-FAILED" TO VALIDATION-STATUS
                   MOVE XML-ERROR-LINE TO ERROR-LINE
                   MOVE XML-ERROR-COLUMN TO ERROR-COLUMN
                   MOVE XML-ERROR-MESSAGE TO ERROR-MESSAGE
                   DISPLAY "Validation failed at line " ERROR-LINE
                   DISPLAY "Column " ERROR-COLUMN ": " ERROR-MESSAGE
               NOT ON EXCEPTION
                   MOVE "VALIDATION-SUCCESS" TO VALIDATION-STATUS
                   DISPLAY "Order XML is valid"
           END-XML
           
           DISPLAY "Final status: " VALIDATION-STATUS
           STOP RUN.

XML-SCHEMA validation with detailed error handling and reporting.

Conditional Schema Validation

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
       IDENTIFICATION DIVISION.
       PROGRAM-ID. XML-CONDITIONAL-VALIDATION.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  XML-DOCUMENT    PIC X(1000).
       01  XML-SCHEMA-FILE PIC X(100).
       01  VALIDATION-REQUIRED PIC X VALUE "Y".
       01  VALIDATION-STATUS PIC X(20).
       01  DOCUMENT-TYPE    PIC X(20).
       
       PROCEDURE DIVISION.
           * Determine document type and schema
           IF DOCUMENT-TYPE = "CUSTOMER"
               MOVE "customer.xsd" TO XML-SCHEMA-FILE
           ELSE IF DOCUMENT-TYPE = "ORDER"
               MOVE "order.xsd" TO XML-SCHEMA-FILE
           ELSE IF DOCUMENT-TYPE = "PRODUCT"
               MOVE "product.xsd" TO XML-SCHEMA-FILE
           ELSE
               MOVE "N" TO VALIDATION-REQUIRED
           END-IF
           
           * Perform validation if required
           IF VALIDATION-REQUIRED = "Y"
               XML PARSE XML-DOCUMENT
                   VALIDATING XML-SCHEMA-FILE
                   ON EXCEPTION
                       MOVE "VALIDATION-FAILED" TO VALIDATION-STATUS
                       DISPLAY "Schema validation failed"
                   NOT ON EXCEPTION
                       MOVE "VALIDATION-SUCCESS" TO VALIDATION-STATUS
                       DISPLAY "Schema validation passed"
               END-XML
           ELSE
               MOVE "NO-VALIDATION" TO VALIDATION-STATUS
               DISPLAY "No schema validation performed"
           END-IF
           
           STOP RUN.

Conditional XML-SCHEMA validation based on document type.

Validation Types

Structure Validation

Validates element hierarchy and relationships.

xml
1
2
3
4
5

  John Doe
  12345
  john@example.com

Data Type Validation

Ensures data conforms to expected types.

xml
1
2
3
4
5
6

  Widget
  29.99
  5
  true

Constraint Validation

Enforces business rules and constraints.

xml
1
2
3
4
5
6

  12345
  150.00
  pending

Required Element Validation

Ensures required elements are present.

xml
1
2
3
4
5
6

  12345
  John Doe
  IT

Best Practices

  • Schema design - Design schemas that accurately reflect business requirements
  • Error handling - Implement comprehensive error handling for validation failures
  • Performance consideration - Balance validation thoroughness with performance requirements
  • Schema maintenance - Keep schemas updated with business rule changes
  • Testing - Test validation with various document scenarios

XML-SCHEMA Quick Reference

Validation TypePurposeUse Case
Structure ValidationEnsures correct element hierarchyDocument structure compliance
Data Type ValidationValidates data format and typeData integrity assurance
Constraint ValidationEnforces business rulesBusiness logic compliance
Required Element ValidationEnsures mandatory elements presentCompleteness checking

Test Your Knowledge

1. What is the primary purpose of XML-SCHEMA in COBOL?

  • To generate XML documents
  • To validate XML documents against schema definitions and enforce structure
  • To format XML output
  • To parse XML documents

2. How does XML-SCHEMA validation work in COBOL?

  • It only checks for well-formed XML
  • It validates XML against schema definitions to ensure structure and data type compliance
  • It only validates element names
  • It ignores all validation rules

3. What is the main benefit of using XML-SCHEMA validation?

  • It makes XML processing faster
  • It ensures data integrity and structure compliance
  • It reduces memory usage
  • It simplifies XML generation

4. How does XML-SCHEMA handle validation errors?

  • It ignores all errors
  • It reports validation errors and can halt processing
  • It only logs errors without stopping
  • It automatically fixes errors

5. What is a common use case for XML-SCHEMA validation?

  • Processing any XML document
  • Validating XML documents in data exchange scenarios where structure compliance is critical
  • Generating XML documents
  • Parsing simple XML

Frequently Asked Questions

Related Concepts

XML Processing

XML and JSON processing in COBOL.

Data Validation

Data validation techniques in COBOL.

Error Handling

Error handling and exception management.

XML-NAMESPACE

Namespace-aware XML processing.

Data Processing

Data processing and manipulation techniques.

XML-NNAMESPACE-PREFIXZERO