A Java/XML binding compiler takes as input a schema description (in
most cases an XML schema, but it may be a DTD, a RelaxNG schema,
a Java class inspected via reflection, or a database schema). The
output is a set of Java classes: * A Java bean class matching the
schema description. (If the schema was obtained via Java
reflection, the original Java bean class.)

* Read a conforming XML document and convert it into the equivalent
Java bean.

* Vice versa, marshal the Java bean back into the original XML
document.