feat: Migrate COBOL codebase to Java Spring Boot application

[devin-ai-integration]

Summary

Migrates the ~18 COBOL example modules to a Java Spring Boot application under a new java-migration/ directory. The original COBOL code is preserved for side-by-side comparison.

What's included

Project Setup (Phase 1)

• Maven-based Spring Boot 3.2.5 project with Spring Web, Data JPA, Validation, Flyway, Jackson XML, JAXB, and Apache POI

Data Layer (Phase 2)

• Account JPA entity mapping the COBOL ws-sql-account-record (sql/sql_example.cbl lines 44-52) with field sizes matching PIC clauses
• AccountRepository with Spring Data JPA query methods replacing the three COBOL cursors: ACCOUNT-ALL-CUR, ACCOUNT-DISABLED-CUR, ACCOUNT-QUERY-CUR
• Flyway migration V1__create_accounts_table.sql derived from sql/create_test_db.sql
• GlobalExceptionHandler (@RestControllerAdvice) replacing the check-sql-state paragraph

Service Layer (Phase 3)

• AccountService encapsulating business logic from the COBOL procedure division (display-all-accounts, display-disabled-accounts, query-accounts)
• SerializationService replacing JSON GENERATE and XML GENERATE with Jackson and JAXB
• ReportService replacing COBOL Report Writer (RD, PAGE LIMIT, HEADING, DETAIL, FOOTING)
• StringUtils utility class replacing COBOL intrinsics: TRIM, UNSTRING, IS NUMERIC, NUMVAL

DTOs (Phase 3)

• JsonRecord with @JsonProperty annotations matching COBOL NAME OF mappings and @JsonInclude(NON_EMPTY) for SUPPRESS WHEN SPACES
• XmlRecord with @XmlAttribute for TYPE OF ... IS ATTRIBUTE and null suppression for SUPPRESS WHEN SPACES
• SearchItem with Comparable for SEARCH ALL binary search (ascending key pattern)

REST API (Phase 4)

• AccountController: GET /api/accounts, GET /api/accounts/disabled, GET /api/accounts/search?q={value} — replacing the terminal menu system
• DemoController: GET /api/demo/json, GET /api/demo/xml, GET /api/demo/report, GET /api/demo/search, GET /api/demo/args — demonstrating non-SQL module equivalents

Configuration (Phase 4)

• application.properties with PostgreSQL connection details matching the COBOL connection string (localhost:5432/cobol_db_example)

Tests (Phase 5)

• 41 passing tests across 5 test classes: AccountRepositoryTest (9 integration tests with H2), AccountServiceTest (5 unit tests), AccountControllerTest (4 web layer tests), SerializationServiceTest (7 tests), StringUtilsTest (17 tests)

COBOL-to-Java Mapping Summary

COBOL Module	Java Equivalent
sql/sql_example.cbl (cursors, menu, check-sql-state)	Account entity/repo/service/controller + GlobalExceptionHandler
json_generate/json_generate.cbl	JsonRecord + SerializationService + DemoController
xml_generate/xml_generate.cbl	XmlRecord + SerializationService + DemoController
report_writer/report_test.cbl	ReportService + DemoController
search/search.cbl (SEARCH ALL)	SearchItem + Collections.binarySearch()
sub_program/main_app.cbl (CALL BY CONTENT/REFERENCE)	Spring service injection
unstring/, trim/, is_numeric/, numval_test/	StringUtils
comp_test/ (COMP/COMP-5)	Native Java int/long
redifines/ (REDEFINES)	Separate DTO classes
merge_sort/ (MERGE/SORT)	Collections.sort() / SQL ORDER BY
read_command_args/	DemoController /api/demo/args endpoint

Review & Testing Checklist for Human

• Verify AccountRepository.searchAccounts() LIKE query produces same results as the COBOL ACCOUNT-QUERY-CUR cursor with trimmed/wildcarded input
• Confirm XmlRecord JAXB output matches the COBOL XML GENERATE structure (enabled as attribute, blank suppressed)
• Check that the Flyway migration script matches your actual PostgreSQL schema and test data
• Run mvn test locally to verify all 41 tests pass in your environment
• Start the Spring Boot app against a real PostgreSQL instance and test the REST endpoints

Notes

• The project uses Java 17 as the target (compatible with Java 21+ runtime)
• H2 in-memory database is used for tests; production targets PostgreSQL
• Added **/target/ to .gitignore to exclude Maven build artifacts

Link to Devin session: https://app.devin.ai/sessions/d18c2fba88af44dbb6e71e5957afb870
Requested by: @jerryoliphant-cog

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