Develop Reference

Using Apache Commons Digester with JSON

I am writing a class that extends a class that uses Digester to parse an XML response from an API (Example existing class, code snipper below). After receiving the response, the code creates an object and adds specific methods on that.
Code snippet edited for brevity:
private Digester createDigester() {
Digester digester = new Digester();
digester.addObjectCreate("GeocodeResponse/result", GoogleGeocoderResult.class);
digester.addObjectCreate("GeocodeResponse/result/address_component", GoogleAddressComponent.class);
digester.addCallMethod("GeocodeResponse/result/address_component/long_name", "setLongName", 0);
...
digester.addSetNext("GeocodeResponse/result/address_component", "addAddressComponent");
Class<?>[] dType = {Double.class};
digester.addCallMethod("GeocodeResponse/result/formatted_address", "setFormattedAddress", 0);
...
digester.addSetNext("GeocodeResponse/result", "add");
return digester;
}
}
The API that I will be calling, however, only supports JSON. I have found a probable solution, which involves converting the JSON to XML and then running it through Digester, but that seems incredibly hackish.
public JsonDigester(final String customRootElementName) {
super(new JsonXMLReader(customRootElementName));
}
Is there a better way to do this?

This class is specifically meant to deal with XML as per the documentation:
Basically, the Digester package lets you configure an XML -> Java
object mapping module, which triggers certain actions called rules
whenever a particular pattern of nested XML elements is recognized. A
rich set of predefined rules is available for your use, or you can
also create your own.
Why would you think it would work with JSON?

Serializing and deserializing XText Model Instance to OutputStream

I have the following use case. I need to transfer an XText model instance via the network in some serialized format. For this purpose I need to serialize the model on the client side, send it as the body of some kind of POST request and deserialize it on the server side.
At the time I issue the send request I do only have access to the object structure of my model. I do not have the files I created the model from any more (it would be possible, but it would destroy the cleanliness of my architecture and makes testing very complex).
I created the following code for serializing the model based on some threads here on StackOverflow and tutorials available via other Websites to serialize an XText-Model
Resource.Factory.Registry.INSTANCE.getExtensionToFactoryMap( ).put("xtextbin", new XMIResourceFactoryImpl());
Injector injector = Guice.createInjector(new ScenarioRuntimeModule());
Serializer serializer = injector.getInstance(Serializer.class);
System.out.println(serializer.serialize(scenario));
However it does not work and I get the following error:
com.google.inject.CreationException: Guice creation errors:
1) Error injecting constructor, org.eclipse.emf.common.util.WrappedException: org.eclipse.emf.ecore.resource.impl.ResourceSetImpl$1DiagnosticWrappedException: com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: Ungültiges Byte 1 von 1-Byte-UTF-8-Sequenz.
The problem most likely lies with the XMIResourceFactoryImpl, which I do not know how to use properly.
Another approach might be to use:
String serializedScenario = ModelUtils.serialize(scenario);
But I do not know how to deserialize the result of this serialize call.
My question however is more basic, since the code above might be a completely wrong approach. Unfortunately I did not find very much about this in the documentation or anywhere else on the Web.
TL;DR:
What is the best way to serialize an XText object model and to deserialize it again?

The first line doesn't belong here at all, just remove it.
How did you create/obtain the object 'scenario'?
If it was parsed with Xtext already you can obtain the serializer like this:
((XtextResource)scenario.eResource()).getResourceServiceProvider
.get(ISerializer.class)

Getting empty sequence for the complex type in generated XSD when developing JAX-WS web services

I seem to be having an issue with Java and NetBeans when it comes to writing web services.
I have searched for a couple of days with no luck, finding people with the same issue as me with zero replies.
I have created a web service which returns a complex type (LoginReply), and that complex type contains an array of another complex type (AppInfo)
However when I generate the WSDL from this, the complex type definition in the XSD is blank, and manually adding the information still makes the web service return null even when data is successfully passed to the web service.
<xs:complexType name="appInfo">
<xs:sequence/>
</xs:complexType>
LoginReply: http://pastebin.com/Umx6ayvi
AppInfo: http://pastebin.com/566WnZ4H
If anyone could point out what I'm doing wrong, or if this is a bug with NetBeans, I'm new to Java so I can't rule out that I'm simply not understanding something, but I'm close to pulling my hair out here.
EDIT:
Just noticed when i deploy to tomcat via NetBeans I get the following error:
WARNING: duplicate class definition bug occured? Please report this : uk/co/example/ComplexTypes/LoginReply$JaxbAccessorM_getApplications_setApplications_[Luk_co_example_ComplexTypes_AppInfo;
java.lang.ClassFormatError: Illegal class name "uk/co/example/ComplexTypes/LoginReply$JaxbAccessorM_getApplications_setApplications_[Luk_co_example_ComplexTypes_AppInfo;" in class file uk/co/example/ComplexTypes/LoginReply$JaxbAccessorM_getApplications_setApplications_[Luk_co_example_ComplexTypes_AppInfo;
Notice the random L before co_uk_example. My research suggests this is an old bug that should be fixed, and that no one else has reported this issue in over a year, no sure where to go from here.
Another edit:
Just added a new web method on the service that simply gets a list of appInfo and returns it to the client. This still fails the same way with NetBeans refusing to generate a sequence inside AppInfo.
I'm sure I'm missing something to declare the class, but I have checked it countless times to ensure I'm not missing anything.

warning gives you good hint: "WARNING: duplicate class definition bug occured"
your ws implementation class directly uses LoginReply class which directly uses AppInfo (+you are maybe also directly using this class in your ws implementation) => jaxb finds it
#XMLSeeAlso(...) tells jaxb to "link" referenced class
=> two definitions of the same class (not sure if it is by design or a bug that jaxb is not able to handle this case more gracefully)
to fix this just remove #XmlSeeAlso from your LoginReply class and you should be fine

This Issue came down to a very simple mistake. The AppInfo class was using non-standard getters and setters.
public void SetAppID(int AppID)
{
this.AppID = AppID;
}
This is INCORRECT (notice the capital on the Set), it should be:
public void setAppID(int AppID)
{
this.AppID = AppID;
}
Using a capital is not standard for JavaBeans and as such JAX-WS didn't know how to generate WSDL for this class. Thanks too shyam from the following link for answering the question
How to return a custom complex type in JAX-WS web services?

I don't think you can send "complex types" over the net (programmed port types) in http protocol, however an array may be implicitly converted to a delimited string set , check the docs for data transfer.

Way to serialize a GWT client side object into a String and deserialize on the server?

Currently our application uses GWT-RPC for most client-server communication. Where this breaks down is when we need to auto generate images. We generate images based on dozens of parameters so what we do is build large complex urls and via a get request retrieve the dynamically built image.
If we could find a way to serialize Java objects in gwt client code and deserialize it on the server side we could make our urls much easier to work with. Instead of
http://host/page?param1=a&param2=b&param3=c....
we could have
http://host/page?object=?JSON/XML/Something Magicical
and on the server just have
new MagicDeserializer.(request.getParameter("object"),AwesomeClass.class);
I do not care what the intermediate format is json/xml/whatever I just really want to be able stop keeping track of manually marshalling/unmarshalling parameters in my gwt client code as well as servlets.

Use AutoBean Framework. What you need is simple and is all here http://code.google.com/p/google-web-toolkit/wiki/AutoBean

I've seen the most success and least amount of code using this library:
https://code.google.com/p/gwtprojsonserializer/
Along with the standard toString() you should have for all Object classes, I also have what's called a toJsonString() inside of each class I want "JSONable". Note, each class must extend JsonSerializable, which comes with the library:
public String toJsonString()
{
Serializer serializer = (Serializer) GWT.create(Serializer.class);
return serializer.serializeToJson(this).toString();
}
To turn the JSON string back into an object, I put a static method inside of the same class, that recreates the class itself:
public static ClassName recreateClassViaJson(String json)
{
Serializer serializer = (Serializer) GWT.create(Serializer.class);
return (ClassName) serializer.deSerialize(json, "full.package.name.ClassName");
}
Very simple!

How to get control over JAXBContext in JAX-WS?

I need to deploy the same web service for each customer. This #javax.jws.WebService uses Object as method arguments and return types (resulting in <xs:anyType/> in wsdl). Each instance of web service is deployed along with customer's jar on the classpath. This jar has known structure and contains JAXB-annotated classes which client wants to handle via my service.
The problem is that when customer passes an instance of his class as method agrument, server-side JAXB context unmarshals it into some strange xerces dom node because (as I understand it) during the deployment time only #WebMethod and #WebService annotations were scanned which, as was already said, are all dealing with Object only.
Simply speaking, I need to hint JAXB at WEB-INF/lib/customer_classes_14586.jar which means taking some control over JAXBContext creation during JAX-WS deployment.
Is it possible at all?
Server-specific solutions are fine (glassfish 3.1 with metro ws stack)
UPDATE
I've missed one thing that might be important: I deploy these web services as OSGI bundles at runtime via web admin console. When I press deploy button new jar is programmatically built up from customer library, webservice class, wsdl and manifests. So I could interfere in build process and provide hinting information at this point of time if this helps.

First option is #UsesJAXBContext annotation. More info here: Specify JAXB Packages in SLSB and JAX-WS
I haven't tested it cause when I found this annotation I've been already halfway towards other solution which might be helpful for others.
The key is using #WebServiceProvider instead of #WebService, a bit low-level but simple:
#WebServiceProvider(
wsdlLocation = "WEB-INF/wsdl/injector.wsdl"
)
#ServiceMode(value = Service.Mode.PAYLOAD)
public class InjectorService implements Provider<Source> {
private Unmarshaller unmarshaller;
#Override
public Source invoke(Source request) {
try {
DOMResult requestDom = new DOMResult();
Transformer trans = TransformerFactory.newInstance().newTransformer();
trans.transform(request, requestDom);
Node requestNode = requestDom.getNode();
// Get the operation name node.
Node operationNode = requestNode.getFirstChild();
// Get the parameter node.
Node parameterNode = operationNode.getFirstChild();
// Unmarshal
JAXBElement<Object> element = unmarshaller.unmarshal(parameterNode, Object.class);
Object unmarshalled = element.getValue();
// Handling customer object and response ......
} catch (Exception e) {
throw new RuntimeException("Endpoint error", e);
}
}
protected Class[] getCustomerClasses() {
// return customer classes somehow
}
#PostConstruct
public void init() throws Exception {
JAXBContext jbc = JAXBContext.newInstance(getCustomerClasses());
unmarshaller = jbc.createUnmarshaller();
}
}
That's it. Customer classes can be obtained from classpath, bundle context or whatever.

From what I know, there is no "declarative" way of hinting an alternative way to unmarshall, on top of the one you already have in place as per JAX-WS, or JAXB - what you're looking for. By the way, the "strange" Xerces node is actually expected, since xsd:any/anyType and Object go hand in hand in your scenario.
My suggestion is to use a relatively simple and portable solution: build your own thin "binding" layer inside your generic web method. All it does for the inbound, is to do the unmarshalling of the XML node to the Java class as per your other JAXB bindings. It must then lookup a Java package name (for your JAXBContext) from the QName of the DOM Element unmarshalled by your WS stack. The lookup can use properties file, reflection or any other mechanism specific to your deployment. For the outbound (return) you then apply a reverse logic to marshall the response. This approach is actually quite common, particularly when other type of unsupported-XML bindings technologies are "tunnelled" through a standard WS stack.