TwinMapper

Compile-time-first Code Generation & Mapping Platform

Generate strongly typed DTOs, binders, validators, and object mappers from YAML, JSON, and BPMN definitions. Bind documents and map between Java layers — all without runtime reflection.

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Two Engines, One Platform

Document binding + object mapping, unified

Most Java applications need two things that are painful at scale: binding structured documents into typed models, and mapping data between architectural layers. TwinMapper solves both from a single definition source.

Document Engine

Reads YAML, JSON, and BPMN definitions at build time. Generates DTOs, enums, binders, validators, registries, and metadata. At runtime, binds documents into generated DTOs via the NodeCursor abstraction — no reflection at binding time.

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Object Engine

Generates typed Java-to-Java mappers for layer-crossing flows: entity↔domain, domain↔DTO, request↔command, and more. Three mapper modes — CREATE, UPDATE, and PATCH — each with explicit null-handling policies.

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Core Capabilities

Built for production Java

Everything you need to run reliable, type-safe code generation and mapping workloads — from a developer's laptop to enterprise-scale pipelines.

Compile-time Safety

Mismatches caught at build time
Zero runtime reflection in binding
Generated, debuggable source
Deterministic — identical inputs, identical outputs

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Three Formats

YAML definitions & binding
JSON definitions & binding
BPMN XML definitions & binding
NodeCursor unifies all three

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Five-Stage Pipeline

Validate → Plan → Generate
Customize (SPI) → Render
11 specialized generators
Render-only, no filesystem writes

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Spring-Native

Spring Boot auto-configuration
Spring Validation integration
ConversionService backend
Actuator + test utilities

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Extensible SPIs

DefinitionReader SPI
RuntimeDocumentParser SPI
CodegenCustomizer SPI
ValueConverter + ValidationExtension

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Use Cases

What teams build with TwinMapper

Document Binding

Bind YAML, JSON, and BPMN XML documents into generated DTOs at runtime using format-neutral NodeCursor traversal. No reflection, no heuristic guessing.

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Layer-to-Layer Mapping

Generate typed mappers for entity↔domain, domain↔DTO, request↔command flows. CREATE, UPDATE, and PATCH modes with explicit null-handling policies.

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Schema-Driven Code Generation

Generate DTOs, enums, binders, validators, registries, and metadata descriptors from a single YAML definition. Replace jsonschema2pojo and hand-written mapper code.

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Core Modules

Format Engines

Code Generators

Pipeline Stages

Recent Updates

Latest from TwinMapper

April 2026TwinMapper Team

Phase 3 Complete — Code Generation Engine Locked

The twinmapper-codegen module is now complete with all 11 generators operational. The five-stage pipeline (Validate → Plan → Generate → Customize → Render) produces DTOs, enums, binders, validators, registries, metadata, and all three mapper modes.

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March 2026TwinMapper Team

Phase 2 — All Three Format Readers Passing

YAML, JSON, and BPMN format readers are fully operational with 351 tests passing. Each reader parses definition files into the canonical DefinitionSet meta-model, ready for code generation.

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February 2026TwinMapper Team

Architecture Document Published

The TwinMapper architecture document is now available, covering the two-engine design, 14-module structure, five-stage pipeline, NodeCursor abstraction, and all seven SPIs.

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