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EclipseLink/Development/2.1/DynamicMOXy/296967/BootstrapFromXSD
Dynamic MOXy - Bootstrapping from XML Schema
Overview
Support for bootstrapping a DynamicJAXBContext from an XML Schema file (XSD) will be implemented in multiple phases. For each phase, test schemas will be created that would result in the following annotations being generated by XJC. A DynamicJAXBContext will then be created from each schema, and an example object will be marshalled. The resulting document will be inspected to ensure that it was marshalled properly, according to the annotations being tested.
Generating a DynamicJAXBContext with XJC
A DynamicJAXBContext is created from an XSD in the following way:
- The schema is parsed using com.sun.tools.xjc.api.SchemaCompiler, resulting in a com.sun.codemodel.JCodeModel being generated.
- JCodeModel contains XJC representations (com.sun.codemodel.JDefinedClass) of the classes to be generated. We iterate over the collection of JDefinedClasses to create EclipseLink representations of the same classes (org.eclipse.persistence.jaxb.javamodel.xjc.*)
- This collection of EclipseLink javamodel classes is then passed to org.eclipse.persistence.jaxb.compiler.Generator, which generates a standard EclipseLink project.
- A Dynamic Project is then created from the standard project via DynamicTypeBuilder.loadDynamicProject().
- An org.eclipse.persistence.oxm.XMLContext is then created from the Dynamic Project, and a DynamicJAXBContext is returned backed by this XMLContext.
Development Phases
Phase 1
Annotation | XML Metadata Tag | Package | Type | Field | Method |
---|---|---|---|---|---|
XmlNs | xml-ns | ||||
XmlSchema | xml-schema | X | |||
XmlSeeAlso | xml-see-also | X | |||
XmlTransient | xml-transient | X | X | X |
The following example schema demonstrates how these annotations will be derived from the schema:
Example Schema
<?xml version="1.0" encoding="UTF-8"?> <xs:schema targetNamespace="myNamespace" xmlns:myns="myNamespace" xmlns:xs="http://www.w3.org/2001/XMLSchema" attributeFormDefault="qualified" elementFormDefault="qualified"> <xs:element name="person" type="myns:person"/> <xs:complexType name="person"> <xs:sequence> <xs:element name="name" type="xs:string"/> </xs:sequence> </xs:complexType> <xs:complexType name="customer"> <xs:complexContent> <xs:extension base="myns:person"> <xs:sequence> <xs:element name="customer-id" type="xs:int"/> </xs:sequence> </xs:extension> </xs:complexContent> </xs:complexType> <xs:complexType name="employee"> <xs:complexContent> <xs:extension base="myns:person"> <xs:sequence> <xs:element name="employee-id" type="xs:string"/> </xs:sequence> </xs:extension> </xs:complexContent> </xs:complexType> </xs:schema>
- The targetNamespace and elementFormDefault property will result in an XmlSchema annotation on the generated package-info class.
- The inheritance relationship between person, customer, and employee will result in an XmlSeeAlso annotation on the generated Person class.
Limitations
- XJC does not interpret the attributeFormDefault property during schema parsing, and will therefore not generate this property in the XmlSchema annotation.
- There is no XML Schema construct that will result in an XmlTransient annotation being generated.
Phase 2
Annotation | XML Metadata Tag | Package | Type | Field | Method |
---|---|---|---|---|---|
XmlAccessorOrder | xml-accessor-order | X | X | ||
XmlAccessorType | xml-accessor-type | X | X | ||
XmlRootElement | xml-root-element | X | |||
XmlType | xml-type | X |
The following example schema demonstrates how these annotations will be derived from the schema:
Example Schema
<?xml version="1.0" encoding="UTF-8"?> <xs:schema targetNamespace="myNamespace" xmlns:myns="myNamespace" xmlns:xs="http://www.w3.org/2001/XMLSchema" attributeFormDefault="qualified" elementFormDefault="qualified"> <xs:element name="individuo" type="myns:person"/> <xs:complexType name="person"> <xs:sequence> <xs:element name="id" type="xs:int"/> <xs:element name="first-name" type="xs:string"/> <xs:element name="last-name" type="xs:string"/> <xs:element name="phone-number" type="xs:string"/> <xs:element name="email" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:schema>
- The name property of the root element will appear in the XmlRootElement annotation's name property.
- The order of the elements of the person type will be captured in the XmlType annotation's propOrder property.
Limitations
- There is no XML Schema construct that will result in the generation of XmlAccessorOrder or XmlAccessorType annotations.
Phase 3
Annotation | XML Metadata Tag | Package | Type | Field | Method |
---|---|---|---|---|---|
XmlAttribute | xml-attribute | X | X | ||
XmlElement | xml-element | X | X | ||
XmlAdapter | xml-java-type-adapter | X | X | X | X |
The following example schema demonstrates how these annotations will be derived from the schema:
Example Schema
<?xml version="1.0" encoding="UTF-8"?> <xs:schema targetNamespace="myNamespace" xmlns:myns="myNamespace" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="person" type="myns:person"/> <xs:complexType name="person"> <xs:sequence> <xs:element name="type" type="xs:string"/> </xs:sequence> <xs:attribute name="id" type="xs:int"/> </xs:complexType> </xs:schema>
- The type field of the generated class will be annotated with @XmlElement.
- The id field of the generated class will be annotated with @XmlAttribute.
Limitations
- There is no XML Schema construct that will result in the generation of an XmlAdapter annotation.
Phase 4
Annotation | XML Metadata Tag | Package | Type | Field | Method |
---|---|---|---|---|---|
XmlElementWrapper | xml-element-wrapper | X | X | ||
XmlList | xml-list | X | X | ||
XmlValue | xml-value | X | X | ||
XmlAnyElement | xml-any-element | X | X | ||
XmlAnyAttribute | xml-any-attribute | X | X | ||
XmlMixed | xml-mixed | X | X |
Phase 5
Annotation | XML Metadata Tag | Package | Type | Field | Method | Schema Representation |
---|---|---|---|---|---|---|
XmlID |
xml-id | X | X | public class Customer { @XmlAttribute @XmlID public String getCustomerID(); public void setCustomerID(String id); } <xs:complexType name="Customer"> <xs:complexContent> <xs:sequence> .... </xs:sequence> <xs:attribute name="customerID" type="xs:ID"/> </xs:complexContent> </xs:complexType> | ||
XmlIDREF |
xml-idref | X |
X |
public class Shipping { @XmlIDREF public Customer getCustomer(); public void setCustomer(Customer customer); .... } <xs:complexType name="Shipping"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:IDREF"/> .... </xs:sequence> </xs:complexContent> </xs:complexType> |
Phase 6
Annotation | XML Metadata Tag | Package | Type | Field | Method | Schema Representation |
---|---|---|---|---|---|---|
XmlElements | xml-elements | X | X | public class Foo { @XmlElements( @XmlElement(name="A", type=Integer.class), @XmlElement(name="B", type=Float.class) } public List items; } <xs:complexType name="Foo"> <xs:sequence> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element name="A" type="xs:int"/> <xs:element name="B" type="xs:float"/> <xs:choice> </xs:sequence> </xs:complexType> | ||
XmlElementRef | xml-element-ref | X | X | @XmlRootElement(name="target") class Target { // The presence of @XmlElementRef indicates that the XML // element name will be derived from the @XmlRootElement // annotation on the type (for e.g. "jar" for JarTask). @XmlElementRef List<Task> tasks; } abstract class Task {} @XmlRootElement(name="jar") class JarTask extends Task { ... } @XmlRootElement(name="javac") class JavacTask extends Task { ... } <xs:element name="target" type="Target"> <xs:complexType name="Target"> <xs:sequence> <xs:choice maxOccurs="unbounded"> <xs:element ref="jar"> <xs:element ref="javac"> </xs:choice> </xs:sequence> </xs:complexType> | ||
XmlElementRefs | xml-element-refs | X |
X |
N/A ?
Referenced in XJC code but unsure how it is specified from Schema |
Phase 7
Annotation | XML Metadata Tag | Package | Type | Field | Method | Schema Representation |
---|---|---|---|---|---|---|
XmlSchemaType | xml-schema-type | X | X | X | public class USPrice { @XmlElement @XmlSchemaType(name="date") public XMLGregorianCalendar date; } <xs:complexType name="USPrice"/> <xs:sequence> <xs:element name="date" type="xs:date"/> </sequence> </xs:complexType> | |
XmlSchemaTypes | xml-schema-types | X | |
|
N/A |
Phase 8
Annotation | XML Metadata Tag | Package | Type | Field | Method | Schema Representation |
---|---|---|---|---|---|---|
XmlEnum | xml-enum | X | @XmlEnum(String.class) public enum Card { CLUBS, DIAMONDS, HEARTS, SPADES } <xs:simpleType name="Card"> <xs:restriction base="xs:string"/> <xs:enumeration value="CLUBS"/> <xs:enumeration value="DIAMONDS"/> <xs:enumeration value="HEARTS"/> <xs:enumeration value="SPADES"/> </xs:simpleType> | |||
XmlEnumValue | xml-enum-value | X |
X |
N/A |
Phase 9
Annotation | XML Metadata Tag | Package | Type | Field | Method | Schema Representation |
---|---|---|---|---|---|---|
XmlInlineBinaryData | xml-inline-binary-data | X | X | X | N/A |
Phase 10
Annotation | XML Metadata Tag | Package | Type | Field | Method | Schema Representation |
---|---|---|---|---|---|---|
XmlElementDecl | xml-element-decl | X | X | N/A ?
Only used for ObjectFactory.java | ||
XmlRegistry | xml-registry | X | N/A ?
Only used for ObjectFactory.java |
Design
When constructing a DynamicJAXBContext
from XML Schema, we can use APIs from the Java XJC compiler to parse a schema and create Java class definitions (XJC's JCodeModel
) in memory, then pass these class definitions to an EclipseLink Generator
(org.eclipse.persistence.jaxb.compiler.Generator
) to generate an EclipseLink project. After we have created this project, we can use the DynamicTypeBuilder
to create a dynamic project, generating Java classes in memory along the way.
First, we use XJC API to parse an XSD and generate a JCodeModel
. Note that this code stops short of actually generating .java
files, it only generates an in-memory representation of the Java files that would normally be created.
// Use XJC API to parse the schema and generate its JCodeModel SchemaCompiler sc = XJC.createSchemaCompiler(); InputSource inputSource = new InputSource(schemaInputStream); sc.parseSchema(inputSource); S2JJAXBModel model = sc.bind(); JCodeModel jCodeModel = model.generateCode(new Plugin[0], null);
We can then wrap these XJC classes in our own implentations of EclipseLink's JAXB JavaModel
classes. This will allow us to use the Generator
to create an EclipseLink project and mappings. The JavaModel
interfaces define "wrappers" for the various Java language constructs that make up the domain model (e.g. classes, methods, constructors, annotations, packages, etc). For example:
public class XJCJavaFieldImpl implements JavaField { // XJC's definition of a Field protected JFieldVar xjcField; ... public int getModifiers() { return xjcField.mods().getValue(); } public String getName() { return xjcField.name(); } ... }
Creating the JavaModel
classes:
// Create EclipseLink JavaModel objects for each of XJC's JDefinedClasses ArrayList<JDefinedClass> classesToProcess = new ArrayList<JDefinedClass>(); Iterator<JPackage> packages = jCodeModel.packages(); while (packages.hasNext()) { JPackage pkg = packages.next(); Iterator<JDefinedClass> classes = pkg.classes(); while (classes.hasNext()) { JDefinedClass cls = classes.next(); classesToProcess.add(cls); } } JavaClass[] jotClasses = createClassModelFromXJC(classesToProcess, jCodeModel);
At this point, we can instantiate a Generator
and obtain a "dry" EclipseLink project, which we can then turn into a dynamic project with generated in-memory classes. Finally, we create and store an XMLContext
and a DynamicHelper
:
// Use the JavaModel to setup a Generator to generate an EclipseLink project XJCJavaModelImpl javaModel = new XJCJavaModelImpl(Thread.currentThread().getContextClassLoader(), jCodeModel); XJCJavaModelInputImpl javaModelInput = new XJCJavaModelInputImpl(jotClasses, javaModel); Generator g = new Generator(javaModelInput); Project p = g.generateProject(); // Make a Dynamic Project from this project, because these classes do not exist on the classpath DynamicClassLoader dynamicClassLoader; if (classLoader instanceof DynamicClassLoader) { dynamicClassLoader = classLoader; } else { dynamicClassLoader = new DynamicClassLoader(classLoader); } Project dp = DynamicTypeBuilder.loadDynamicProject(p, null, dynamicClassLoader); this.xmlContext = new XMLContext(dp); this.dynamicHelper = new DynamicHelper(xmlContext.getSession(0));