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The JAXB 2.0 runtime

. * *

Overview

*

* This module provides code that implements {@link javax.xml.bind.JAXBContext}. * Roughly speaking the runtime works like this: * *

    *
  1. There's a set of classes and interfaces that model JAXB-bound types. * You can think of this as a reflection library for JAXB. *
  2. There's a set of classes that constitute the unmarshaller and marshaller. * Each class represents a small portion, and they are composed to perform * the operations. *
  3. {@link com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl} builds itself by reading the model and * composing unmarshallers and marshallers. *
* *

Interesting Pieces inside Runtime

*

* The followings are the interesting pieces inside the runtime. * *

*
{@link com.sun.xml.internal.bind.v2.model model} *
* This set of classes and interfaces models JAXB-bound types. * *
{@link com.sun.xml.internal.bind.v2.runtime XML I/O} *
* This set of classes implements the JAXB API and provides the XML I/O functionality. *
* *

* The classes NOT in the {@link com.sun.xml.internal.bind.v2} package (and its subpackages) * are also used by old JAXB 1.0 clients. * *

Models

*

* "Model" is the portion of the code that represents JAXB-bound types. * *

* The following picture illustrates the relationship among major * packages of the binding model. * *

* *
* *

* The core model contracts are all interfaces, and they are parameterized * so that they can be used * with different reflection libraries. This is necessary, as the model * is used: *

    *
  1. at runtime to process loaded classes, *
  2. at tool-time to process source files / class files, and *
  3. at schema compile time to generate source code. *
* They all use different reflection libraries. * *

* This portion is used by all * three running mode of JAXB. * The corresponding base-level implementaion * is also parameterized. * *

* The runtime model contract and implementation are used only at the run-time. * These packages fix the parameterization to the Java reflection, * and also exposes additional functionalities to actually do the * unmarshalling/marshalling. These classes have "Runtime" prefix. * *

* Finally XJC has its own implementation of the contract in * its own package. This package also fixes the parameterization * to its own reflection library. * *

* When you work on the code, it is often helpful to know the layer you are in. * * *

* The binding model design roughly looks like the following. * For more details, see the javadoc of each component. * *

* *
* * TODO: link to classes from above pictures * * *

Evolution Rules

* None of the class in this package or below should be directly * referenced by the generated code. Hence they can be changed freely * from versions to versions. * * * * *

Performance Characteristics

*

* Model construction happens inside {@link javax.xml.bind.JAXBContext#newInstance(Class[])}. * It's desirable for this step to be fast and consume less memory, * but it's not too performance sensitive. * *

* Code that implements the unmarshaller and the marshaller OTOH * needs to be very carefully written to achieve maximum sustaining * performance. * * * * *

Bootstrap Sequence

*

* The following picture illustrates how the {@link javax.xml.bind.JAXBContext#newInstance(Class[])} method * triggers activities. * * {@code SequenceDiagram boxwid=1.2; pobject(U,"user"); object(A,"JAXB API"); object(CF,"ContextFactory"); pobject(JC); step(); message(U,A,"JAXBContext.newInstance()"); active(A); message(A,A,"locate JAXB RI 2.0"); active(A); step(); inactive(A); message(A,CF,"createContext"); active(CF); create_message(CF,JC,"c:JAXBContextImpl"); active(JC); message(JC,JC,"build runtime model"); message(JC,JC,"build JaxBeanInfos"); inactive(JC); rmessage(A,U,"return c"); inactive(CF); inactive(A); complete(JC); complete(CF); complete(A); * } * */ package com.sun.xml.internal.bind.v2;