MetaObjects Documentation¶

Welcome to the comprehensive documentation for MetaObjects, a sophisticated framework for metadata-driven development that provides unprecedented control over your applications beyond traditional model-driven development techniques.

Quick Start

Get up and running with MetaObjects in minutes with our step-by-step guide

Getting Started
User Guide

Comprehensive documentation covering all MetaObjects features and modules

User Guide
API Reference

Complete API documentation for all MetaObjects modules and classes

API Reference
Examples

Working examples and tutorials for common use cases and integration patterns

Examples

What is MetaObjects?¶

MetaObjects is a comprehensive suite of tools designed for metadata-driven development, offering:

Metadata-First Architecture¶

Define your object structures, validation rules, and relationships through rich metadata definitions rather than scattered annotations or configuration files.

{
  "metadata": {
    "children": [
      {
        "object": {
          "name": "User",
          "type": "pojo",
          "@dbTable": "users",
          "children": [
            {
              "field": {
                "name": "email",
                "type": "string",
                "@required": true,
                "@maxLength": 255,
                "@pattern": "^[\\w._%+-]+@[\\w.-]+\\.[A-Za-z]{2,}$"
              }
            }
          ]
        }
      }
    ]
  }
}

Cross-Language Code Generation¶

Generate type-safe code for multiple languages from a single metadata definition:

Java: POJOs, JPA entities, builders, validators
TypeScript: Interfaces, classes, React components
C#: Classes, entities, validation attributes
SQL: Database schemas, constraints, indexes

:material-spring: Framework Integration¶

Native support for popular frameworks without forcing dependencies:

Spring BootPlain JavaOSGi Bundle

<dependency>
    <groupId>com.metaobjects</groupId>
    <artifactId>metaobjects-core-spring</artifactId>
    <version>6.2.5-SNAPSHOT</version>
</dependency>

<dependency>
    <groupId>com.metaobjects</groupId>
    <artifactId>metaobjects-core</artifactId>
    <version>6.2.5-SNAPSHOT</version>
</dependency>

<dependency>
    <groupId>com.metaobjects</groupId>
    <artifactId>metaobjects-metadata</artifactId>
    <version>6.2.5-SNAPSHOT</version>
</dependency>

Type-Safe Constraints¶

Comprehensive validation and constraint system that enforces rules at metadata definition time:

Naming patterns and identifier validation
Required attributes and data type enforcement
Uniqueness constraints and relationship validation
Custom business rules through extensible constraint providers

Key Features¶

Performance Optimized¶

Built on a READ-OPTIMIZED WITH CONTROLLED MUTABILITY pattern analogous to Java's Class/Field reflection system:

Load once during application startup (100ms-1s)
Read thousands of times with microsecond performance (1-10μs)
Thread-safe concurrent access without synchronization overhead
Memory efficient with intelligent caching strategies (10-50MB)

Modular Architecture¶

Independent modules that can be used individually or combined as needed:

Module	Purpose	Dependencies
`metaobjects-metadata`	Core metadata definitions	None
`metaobjects-core`	File loading and parsing	metadata
`metaobjects-codegen-*`	Code generation engines	metadata, core
`metaobjects-*-spring`	Spring integrations	Optional

Extensible Plugin System¶

Create custom field types, validators, and generators through a clean provider-based registration system:

public class CurrencyField extends PrimitiveField<BigDecimal> {
    public static void registerTypes(MetaDataRegistry registry) {
        registry.registerType(CurrencyField.class, def -> def
            .type("field").subType("currency")
            .inheritsFrom("field", "base")
            .optionalAttribute("precision", "int")
            .optionalAttribute("currencyCode", "string")
        );
    }
}

Architecture Highlights¶

Memory Model¶

MetaObjects follows a ClassLoader pattern where metadata is loaded once at startup and remains in memory for the application lifetime, similar to how java.lang.Class objects work.

OSGI Compatible¶

Full support for OSGi bundle lifecycle with proper cleanup patterns:

ServiceLoader discovery for dynamic service registration
WeakReference patterns for bundle unloading cleanup
Service registry integration for enterprise environments

Concurrent Read Optimization¶

Designed for high-throughput applications with massive concurrent read access:

Immutable after loading - no synchronization needed for reads
ConcurrentHashMap for high-frequency lookups
Lock-free algorithms in runtime read paths

Getting Started¶

Ready to experience metadata-driven development? Choose your path:

New to MetaObjects?

Start with our comprehensive getting started guide

Quick Start Guide
:material-spring:{ .lg .middle } Spring Developer?

Jump into Spring-specific integration patterns

Spring Integration
Code Generation?

Learn about template-based code generation

Code Generation
Plugin Development?

Extend MetaObjects with custom types and generators

Plugin Guide

Community & Support¶

GitHub Repository: metaobjectsdev/metaobjects-core
Issue Tracker: Report bugs and request features
Discussions: Community support and questions
License: Apache License 2.0

MetaObjects is actively developed and maintained with comprehensive modernization completed in 2024-2025, including security hardening, Java 17 LTS migration, and complete code quality modernization.