Tech Stack & Architecture Components

[Not implemented yet] — the table below is the planned stack, following the "Read first" part of Phase 2.

1. Tech stack breakdown (planned)

Component	Technology / Library	Why
Backend core	Java, Spring Boot	Main platform of both sub-projects
Data access	Spring Data JPA, Hibernate, Flyway	Version control for the DB schema
Database	PostgreSQL	Shared with Sub-project B, easier integration
Orchestration	Spring State Machine	State machine for the Saga Orchestrator
Batch processing	Spring Batch	Chunk-oriented EOD settlement
XML processing	JAXB	Parse & validate ISO 20022 messages (`pain.001`, `pacs.008`)
Testing	JUnit, Spring Boot Test	Unit & integration tests for the business flows

2. Spring Batch configuration for EOD settlement (planned)

java

@Bean
public Step settlementStep(JobRepository jobRepository,
                          PlatformTransactionManager txManager,
                          ItemReader<PendingSettlementRecord> reader,
                          ItemProcessor<PendingSettlementRecord, SettledTransaction> processor,
                          ItemWriter<SettledTransaction> writer) {
    return new StepBuilder("eodSettlementStep", jobRepository)
        .<PendingSettlementRecord, SettledTransaction>chunk(500, txManager)
        .reader(reader)
        .processor(processor)
        .writer(writer)
        .faultTolerant()
        .skip(CorruptedRecordException.class)
        .skipLimit(10)
        .retry(TransientDatabaseException.class)
        .retryLimit(3)
        .build();
}

Why chunk-oriented processing: ADR-005.