Which web service stack allows binding wsdl first web service to existing classes in Java?

Question

Greetings, I have a complicated scenario to handle. I have a wsdl file which uses a particular XML schema. The XML schema is actually a handcrafted implementation of a specification. There is also a Java based implementation of the same specification. So the XSD used in WSDL and Java classes at hand are quite similar, but not exactly same. Almost all web service stacks allow creating classes from WSDL or creating WSDL from Java class annotations. What I want to do, is to use the WSDL and bind XSD used in the wsdl to existing java classes. Should/can I do this by manually replacing generated Java classes with existing ones? Is it a matter of changing type names in config files and moving binding annotations to existing classes? If you know any best practices, or java web service stacks that support this kind if flexibility in a practical way, your response would be much appreciated.

Best Regards Seref

Answer 1

I suggest Spring's Web Services module, which has no code generation involved, but provides a clean separation of concerns. Different concerns are broken out nicely by allowing you to provide your WSDL and existing schema(s) on one side (contract first), your existing Java-based domain model on the other, and a way to plugin in your OXM (Object-XML Mapping) technology of choice.

Since you have hand-crafted WSDL/schema and hand-crafted Java classes, the real work will be in configuring your OXM. I prefer JiBX as it keeps the concerns separated (no XML annotation garbage mixed into your domain) with JAXB as a backup if the learning curve looks too steep. Spring Web Services supports several other OXM frameworks, and you can even use several different ones at once.

As far as best-practices, I consider hand-crafted code a best practice, though I may be in the minority. If you generate classes from XML you end up with classes that are simple data containers with no behavior (assuming you want to regenerate them whenever your WSDL/XSD changes). This is bad if you favor the object-oriented paradigm because you end up having to place your "business logic" in utilities/helpers/services etc. instead of in the domain objects where it really belongs. This is one reason I favor JiBX. I can make very nice OO objects with behavior, a nice clean schema that doesn't necessarily match the objects, and can manage changes to either side with a mapping file similar to how hibernate does it for ORM (Object-Relational Mapping). You can do the same with JAXB, but that requires embedding XML structure into your object model, and binds a single XML representation to it (whereas with JiBX you can have many).

Answer 2

MOXY (I'm the tech lead) was designed for instances where you have an existing XML Schema and an exsting object model. It accomplishes this through XPath based mapping and can ever handle cases where the models are not that similar:

• http://stackoverflow.com/questions/906855/parse-google-geocode-with-xstream/3302823#3302823

MOXy also has an external binding file:

• http://wiki.eclipse.org/EclipseLink/Examples/MOXy/EclipseLink-OXM.XML

MOXy is a JAXB implementation with extensions (A couple of which are mentioned above). IF you go ahead with Spring, MOXy is configured as a JAXB implementation, and you need to add a jaxb.properties file in with your model classes with the following entry:

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory