SchemaBridge

SchemaBridge generates JAXB-annotated Java classes from XML Schema and syncs edited Java mappings back into a copy of the original schema. The reverse operation retains existing schema documentation and annotations, updates mappings represented by the Java source, and adds newly mapped fields and types.

Requirements

• JDK 17 or newer
• Maven 3.8 or newer

Build and test

mvn test

Generate Java

mvn compile exec:java "-Dexec.args=to-java examples/logistics.xsd target/generated-sources/logistics"

An optional final argument sets the generated Java package:

mvn compile exec:java "-Dexec.args=to-java examples/catalog.xsd target/generated-sources/catalog com.example.catalog"

Sync edited Java back to XSD

Edit the generated Java mapping, including JAXB annotations and @XmlType(propOrder) when applicable, then pass the original schema and the directory containing the Java source files:

mvn compile exec:java "-Dexec.args=sync-schema examples/logistics.xsd target/generated-sources/logistics target/roundtrip/logistics.xsd"

SchemaBridge runs JAXB schemagen on the Java sources, then merges the generated declarations into copies of the original schema and its local xs:import/xs:include dependencies. Dependency paths are preserved under the output directory, so the output schema set remains connected. Schemas without generated Java mappings are copied unchanged. Existing xs:documentation and xs:annotation nodes are retained for matching declarations. New mapped fields, attributes, types, and elements are brought across. The original input files are never modified.

The reverse pass follows JAXB mapping rules: Java fields must be visible to JAXB through annotations or access configuration, and generated classes with @XmlType(propOrder) must include newly added properties there. Schema constructs with no Java representation remain from the original XSD.

Example schemas

The examples/ directory contains ten domain schemas plus common-types.xsd. Logistics imports eight schemas (common types, customers, catalog, orders, billing, inventory, learning, and support) to demonstrate a wider dependency graph. Billing also imports common currency types. The schemas demonstrate restrictions, enumerations, documented simple and complex types, attributes, and annotations.

The reverse merger targets named JAXB complex types and their sequence elements/attributes. For substantially different schema structures, review the generated output before adopting it as a contract.