Zeus is, in a nutshell, an open source Java-to-XML Data Binding tool. It provides a means of taking an arbitrary XML document and converting that document into a Java object representing the XML. That Java object can then be used and manipulated like any other Java object in the VM (virtual machine). Then, once the object has been modified and operated upon, Zeus can be used to convert the Java object back into an XML representation.
At the heart of the need for Zeus is the fact that lower level XML
APIs like SAX (the Simple API for XML), DOM (the Document
Object Model), and JDOM provide generic views of an XML document. For
example, DOM and JDOM provide you a tree view of an XML document;
however, a document that represents books is most easily worked with
using methods like
getBook(String title), rather than
getElement(String name) and
content). By providing this higher level API, Zeus seeks to
take even more mystery out of XML and make it simple to use, and
accessible to all.
Core to the process of conversion between XML and Java is a set of constraints. These constraints specify how an XML document should be formatted, and what content in that document means semantically. These constraints cen be represented in the two most common standard formats today, DTDs and XML Schemas. In the future, Zeus will support emerging standards like Relax, and anything else that comes along. With these constraints, Zeus can generate Java classes that will represent any XML document conforming to the supplied constraints. Then, XML documents become instances of these constraints. What does all this mean to you? Well, it means that you can generate your classes and write your code ahead of time, and know that any XML document conforming to your constraints will work with your code, even months and years down the road. Additionally, Zeus provides a binding layer which sits between constraints and class generation. This means that you can interchange XML Schema, DTDs, and any other constraint mechanism at any time, and Zeus will happily go on plugging. This is because Zeus creates a set of generic bindings from constraints, and then generates classes from those bindings; this is in contrast to most binding frameworks today, which go directly from constraint to class.
There's lots more to tell, but you should read up on the various resources in the documentation section to get it all under your belt. That will give you a good idea of what Zeus is. Then, check out the Zeus Roadmap to see where Zeus is going next. And finally, let us know what you think!