Field notes from the Puncharsoft team on SAP, enterprise application development, integration and digitalization.
In a layered architecture the business rule depends on JPA and HTTP; hexagonal architecture inverts that dependency. We walk through the port and adapter structure in Spring Boot, the package layout, a dependency rule protected by ArchUnit, the cost of separating domain from JPA entities, and which projects this architecture actually pays off in, with code.
Writing to the database and publishing to Kafka are two separate operations, and a crash between them leaves systems inconsistent. The outbox pattern solves this dual-write problem with one transaction. We cover a polling relay in Spring Boot, CDC with Debezium, ordering and idempotency guarantees and day-two operations, with code.
Taking an LLM from a chat box into a business process starts with four patterns: schema-bound structured output, RAG over company data, tool calling with clear limits, and input/output guardrails. With Spring AI examples, an LLM gateway architecture, model choice under privacy constraints and measuring with an evaluation set.
Proposals obtained without a specification cannot be compared, and the scope debate lasts until it kills the project. We share the ten sections of an enterprise software specification, the rules for writing testable requirements, an acceptance-criteria example and a pre-RFP checklist.
Virtual threads don't make the CPU faster; they stop waiting requests from consuming threads. How to enable them in Spring Boot with one line, which I/O-heavy scenarios show measurable gains, and the pitfalls — pinning, connection-pool bottlenecks, ThreadLocal bloat — with code.
ERP integration is the real work in most enterprise projects, and it's where they most often fail. When to choose synchronous APIs, asynchronous messaging or batch transfer, how an anti-corruption layer keeps the ERP model out of your application, and the reliability patterns — outbox, idempotency, reconciliation — that keep data flowing.
@Transactional is not an annotation, it is a proxy — and most bugs come from forgetting that. Self-invocation, no rollback on checked exceptions, REQUIRES_NEW exhausting the connection pool, what readOnly really does and transaction behavior that misleads in tests, with code.
The honest answer to "how much will it cost?" is "it depends on scope" — but the factors that set the scope are known. We cover the nine factors that drive the price, person-day math, fixed-price versus time-and-materials contracts, and the line items that never show up in proposals.
A modular monolith only stays modular if its boundaries are enforced at build time. We walk through Spring Modulith's module rules, verification test, event-driven communication with the publication registry, module-level tests and generated documentation, with code.